Android spinner implementation not showing selected item

Android spinner implementation not showing selected item - android

I have 3 Spinners and I am selecting values from each of them. But when I declare the setOnItemSelected() method outside of the onClickListener() of the next button, The selected value doesn't show up in the Toast. When I declare the setOnItemSelected() method inside the onClickListener of the button, it works but then I can't hide my edittext when I select "Set Limit" from the last spinner.
Please help.
Below is my .java file.
public class AvailabilityActivity extends AppCompatActivity {
private Button next;
private Spinner advanceNotice, shortestTrip, longestDist;
private Bundle bundle;
private EditText setLimit;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_availability);
bundle = getIntent().getExtras();
intializeSpinners();
setLimit = (EditText) findViewById(R.id.setlimit);
ArrayAdapter<CharSequence> adapteradvNotice = ArrayAdapter.createFromResource(this, R.array.advNoticeArray, R.layout.spinner_layout);
adapteradvNotice.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
advanceNotice.setAdapter(adapteradvNotice);
ArrayAdapter<CharSequence> adaptershortestTrip = ArrayAdapter.createFromResource(this, R.array.shortestTripArray, R.layout.spinner_layout);
adaptershortestTrip.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
shortestTrip.setAdapter(adaptershortestTrip);
ArrayAdapter<CharSequence> adapterlongestDist = ArrayAdapter.createFromResource(this, R.array.longestDistanceArray, R.layout.spinner_layout);
adapterlongestDist.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
longestDist.setAdapter(adapterlongestDist);
onNextPressed();
}
private void intializeSpinners() {
advanceNotice = (Spinner) findViewById(R.id.acceptAdvanceNotice);
shortestTrip = (Spinner) findViewById(R.id.acceptShortestTrip);
longestDist = (Spinner) findViewById(R.id.acceptLongestTrip);
}
private void onNextPressed() {
next = (Button) findViewById(R.id.nextButton1);
final String[] setLimitText = {""};
final String[] selectedlongestDist = new String[1];
longestDist.setOnItemSelectedListener(new Spinner.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
selectedlongestDist[0] = parent.getItemAtPosition(position).toString();
if (selectedlongestDist[0].equals("Set Limit")){
setLimit.setVisibility(View.VISIBLE);
setLimitText[0] = setLimit.getText().toString();
}
if (selectedlongestDist[0].equals("No Limit")) {
setLimit.setVisibility(View.INVISIBLE);
}
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
if (setLimitText[0] == "")
setLimitText[0] = selectedlongestDist[0];
next.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final String[] selectedNotice = new String[1];
advanceNotice.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
selectedNotice[0] = parent.getItemAtPosition(position).toString();
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
final String[] selectedshortestTrip = new String[1];
shortestTrip.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
selectedshortestTrip[0] = parent.getItemAtPosition(position).toString();
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
Toast.makeText(getApplicationContext(), setLimitText[0], Toast.LENGTH_LONG).show();
bundle.putString("advancenotice", selectedNotice[0]);
bundle.putString("shortesttrip", selectedshortestTrip[0]);
bundle.putString("longesttrip", setLimitText[0]);
Intent intent = new Intent(getBaseContext(),ImageActivity.class);
intent.putExtras(bundle);
startActivity(intent);
}
});
}
}
Below is my layout file.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.csci567.dailyrentals.AvailabilityActivity">
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="How much advance notice do you need to confirm a trip request?"
android:textColor="#000000"
android:textSize="18dp"
android:layout_marginLeft="15dp"
android:id="#+id/advanceNoticeRequestText"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.035"
android:layout_marginStart="15dp" />
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Advance notice"
android:textSize="14dp"
android:id="#+id/advanceNoticeText"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.13"
android:layout_marginStart="15dp" />
<Spinner
android:layout_width="0dp"
android:layout_height="wrap_content"
android:id="#+id/acceptAdvanceNotice"
android:hint="Advance Notice"
style="#style/Widget.AppCompat.Spinner.Underlined"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.18"
android:layout_marginStart="15dp" />
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Block trips that don't give you enough advance notice."
android:textSize="16dp"
android:id="#+id/blockNoticeText"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.26"
android:layout_marginStart="15dp" />
<View android:background="#a8a8a6"
android:layout_width = "0dp"
android:layout_height="1dp"
android:id="#+id/separatorLine1"
android:layout_marginTop="25dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.3"/>
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="How long would you like trips to last?"
android:textSize="18dp"
android:textColor="#000000"
android:id="#+id/tripDurationText"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.4"
android:layout_marginStart="15dp" />
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Shortest possible trip"
android:textSize="14dp"
android:id="#+id/shortestTripText"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.46"
android:layout_marginStart="15dp" />
<Spinner
android:layout_width="0dp"
android:layout_height="wrap_content"
android:id="#+id/acceptShortestTrip"
android:hint="Enter Shortest Trip"
style="#style/Widget.AppCompat.Spinner.Underlined"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.52"
android:layout_marginStart="15dp" />
<TextView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Longest Possible trip"
android:textSize="14dp"
android:id="#+id/longestTripText"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.6"
android:layout_marginStart="15dp" />
<Spinner
android:layout_width="0dp"
android:layout_height="wrap_content"
android:id="#+id/acceptLongestTrip"
android:hint="Enter Longest Trip"
style="#style/Widget.AppCompat.Spinner.Underlined"
android:layout_marginLeft="15dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.66"
android:layout_marginStart="15dp" />
<EditText
android:layout_width="0dp"
android:layout_height="wrap_content"
android:id="#+id/setlimit"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="0.76"
android:hint="Enter the value of longest possible trip"
android:layout_marginStart="15dp"
android:layout_marginLeft="15dp" />
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="35dp"
android:text="Next"
android:textSize="18dp"
android:textColor="#ffffff"
android:background="#8b36bc"
android:id="#+id/nextButton1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintVertical_bias="1.0"/>
</android.support.constraint.ConstraintLayout>

The way you're coding is the problem.
First thing you must change is the place you set listeners. You should avoid setting listeners inside other listeners.
Secondly, the code will execute all the code out of those listeners and then execute the code inside those listeners.
Thirdly, if you wanna show a Toast with a message generated inside a Spinner, you should put it inside the spinner's listener.
Try to reorganize you code thinking of those tips and see if you'll have the problem again.

Related

EditText to be saved to Integer Arraylist

I am trying to get numeric user input on an EditText and I want it to be saved to an Integer Arraylist. I have code here that has numbers added programatically to an arraylist called number. I have also added Textviews to display the entire array and the first element of the array to see if it is good.
What I need help with is the syntax for saving user input into the EditText to the same Arraylist. I have searched this site and found nothing suitable.
I would also like to see the result in the Textview to make sure its working.
enter code hereI am trying to get numeric user input on an EditText and I want it to be saved to an Integer Arraylist. I have code here that has numbers added programatically to an arraylist called number. I have also added Textviews to display the entire array and the first element of the array to see if it is good.
What I need help with is the syntax for saving user input into the EditText to the same Arraylist.
I would also like to see the result in the Textview to make sure its working.
enter code here #Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<Integer> number = new ArrayList<Integer>();
look = (TextView)findViewById(R.id.tv1);
look2 = (TextView)findViewById(R.id.tv2);
setUIViews();
one.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
display1.setText("1");
}
});
two.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
display1.setText("2");
}
});
three.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
display1.setText("3");
}
});
number.add(1);
number.add(22);
number.add(45);
number.add(17);
number.add(0,7);
for (int i=0; i < number.size(); i++){
look2.setText(look2.getText() +" " + number.get(i) + " , ");
look.setText("First element is: "+number.get(0));
}
}
private void setUIViews (){
one = (Button)findViewById(R.id.btn1);
display1 = (EditText)findViewById(R.id.et1);
two = (Button)findViewById(R.id.btn2);
display1 = (EditText)findViewById(R.id.et1);
three = (Button)findViewById(R.id.btn3);
display1 = (EditText)findViewById(R.id.et1);
}
}
enter code here
enter code here<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<EditText
android:id="#+id/et1"
android:layout_width="323dp"
android:layout_height="58dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:ems="10"
android:inputType="number"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.503"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.017" />
<Button
android:id="#+id/btn1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="244dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="244dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:inputType="number"
android:text="1"
android:visibility="visible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.522"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.212" />
<Button
android:id="#+id/btn2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:inputType="number"
android:text="2"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.212" />
<Button
android:id="#+id/btn3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:inputType="number"
android:text="3"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.921"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.212" />
<TextView
android:id="#+id/tv1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.355" />
<TextView
android:id="#+id/tv2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.416" />
<Button
android:id="#+id/btnview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="View Arraylist"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.798" />
enter code here

What I need help with is the syntax for saving user input into the EditText to the same Arraylist.
I think you mean this:
number.add(Integer.parseInt(display1.getText().toString()));

You Can handle EditText.AddonTextChangeListner and cast every 'char' to Int and add it to array and remove in case of deleting i think this will be efficient

setVisibilty to visible from gone not updated in real time

I'm trying a simple act of changing a layout visibility from 'gone' to 'visible'.
the flow is quite simple, clicking on a 'fab' will change the visibilty of a specific layout (in this case: 'threeVal_layout') from gone to visible.
For some reason, the code is working when running without debugging(which means the layout does change to visible), but once I use debug mode the layout is not updated after the code is executed, only after I return to the screen and click on the fab one more time.
I do see the error attached in the image inside View.class, once I step in the 'setVisiblty' function.
my code:
public class SubmitStringsActivity extends AppCompatActivity{
RandomFunctions randomFunc = new RandomFunctions();
EditText firstVal,secVal,thirdVal;
TextInputLayout firstVal_layout,secVal_layout;
public static TextInputLayout threeVal_layout;
FloatingActionButton btn_go,btn_add;
Integer minValOpt= 0;
String firstChoErr,secChoErr,strResult;
public static String[] choicesArr = new String[2]; //Initialize array for 2 since minimum options is 2
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_send_strings);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
/*First Value*/
firstVal = findViewById(R.id.firstVal);
firstVal_layout = findViewById(R.id.firstVal_layout);
/*Second Value*/
secVal = findViewById(R.id.secVal);
secVal_layout = findViewById(R.id.secVal_layout);
/*Third Value*/
thirdVal = findViewById(R.id.thirdVal);
threeVal_layout = findViewById(R.id.threeVal_layout);
btn_add = findViewById(R.id.fab_add);
btn_add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
threeVal_layout.setVisibility(View.VISIBLE);
threeVal_layout.invalidate();
RandomFunctions.addChoiceOption();
}
}); btn_go = findViewById(R.id.button);
btn_go.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), DisplayResultActivity.class);
// Clean any errors
firstVal.setError(null);
// minVal_layout.setErrorEnabled(false);
secVal_layout.setError(null);
// maxVal_layout.setErrorEnabled(false);
// _End_
if (firstVal.getText().toString().equals("")) {
firstChoErr= getString(R.string.emptyChoiceStr); /**Get the error string from the res*/
firstVal_layout.setError(firstChoErr); /**Set error in case minimum value is empty*/
return;
}
else if (secVal.getText().toString().equals("")){
secChoErr= getString(R.string.emptyChoiceStr);
secVal_layout.setError(secChoErr); /**Set error in case maximum value is empty*/
return;
}
else {
/** Called when the user taps the Go button */
choicesArr[0] = (firstVal.getText().toString());
choicesArr[1] = (secVal.getText().toString());
int resVal = randomFunc.calculateNums(minValOpt, choicesArr.length-1); //Send minimum and maximum values to random function
strResult = choicesArr[resVal];
intent.putExtra("intValName", strResult);
startActivity(intent);
//finish();
}
}
}
);
}
}
XML:
<LinearLayout
android:id="#+id/linearStringLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="56dp"
android:background="#color/mainBackGroundHalf1"
android:gravity="center"
android:orientation="vertical"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<android.support.design.widget.TextInputLayout
android:id="#+id/firstVal_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:gravity="center"
app:layout_constraintEnd_toEndOf="#+id/linearStringLayout"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/linearStringLayout">
<EditText
android:id="#+id/firstVal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:layout_marginBottom="8dp"
android:backgroundTint="#color/inputText"
android:ems="10"
android:hint="#string/firstString"
android:imeOptions="actionDone"
android:inputType="text"
android:maxLength="9"
android:selectAllOnFocus="false"
android:singleLine="true"
android:textAlignment="center"
android:textAppearance="#android:style/TextAppearance.Material"
android:textColorHint="#color/inputText"
app:layout_constraintBottom_toBottomOf="#+id/linearStringLayout"
app:layout_constraintHorizontal_bias="0.502"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent" />
</android.support.design.widget.TextInputLayout>
<android.support.design.widget.TextInputLayout
android:id="#+id/secVal_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:gravity="center"
app:layout_constraintEnd_toEndOf="#+id/linearStringLayout"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/firstVal_layout">
<EditText
android:id="#+id/secVal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:backgroundTint="#color/inputText"
android:ems="10"
android:hint="#string/secondString"
android:inputType="text"
android:maxLength="9"
android:selectAllOnFocus="false"
android:singleLine="true"
android:textAlignment="center"
android:textAppearance="#android:style/TextAppearance.Material"
android:textColorHint="#color/inputText" />
</android.support.design.widget.TextInputLayout>
<android.support.design.widget.TextInputLayout
android:id="#+id/threeVal_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:gravity="center"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="#+id/linearStringLayout"
app:layout_constraintEnd_toEndOf="#+id/linearStringLayout"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/secVal_layout">
<EditText
android:id="#+id/thirdVal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:layout_marginBottom="8dp"
android:backgroundTint="#color/inputText"
android:ems="10"
android:hint="#string/threeString"
android:imeOptions="actionDone"
android:inputType="text"
android:maxLength="9"
android:selectAllOnFocus="false"
android:singleLine="true"
android:textAlignment="center"
android:textAppearance="#android:style/TextAppearance.Material"
android:textColorHint="#color/inputText"
android:visibility="visible"
app:layout_constraintBottom_toBottomOf="#+id/linearLayout"
app:layout_constraintHorizontal_bias="0.502"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent" />
</android.support.design.widget.TextInputLayout>
</LinearLayout>

How to center Items in Recyclerview?

I am planing a little app with recyclerviews in it.
Sometimes I have to load only 4 items to it and sometimes over 200.
Now I don't get it, how to center the custom recyclerviews items!
I have a custom recyclerview (grid) and I want to have 4 (2x2) items in it beeing centered.
What I have:
What I want:
So where is my mistake in following code?
fragment_single_pokemon.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context=".MainActivity">
<android.support.constraint.ConstraintLayout
android:id="#+id/cLayTypOne"
android:layout_width="50dp"
android:layout_height="25dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:background="#drawable/customborder_typ"
app:layout_constraintBottom_toTopOf="#+id/cLayTypTwo"
app:layout_constraintEnd_toStartOf="#+id/civSprite"
app:layout_constraintStart_toStartOf="parent">
<TextView
android:id="#+id/txtTypOne"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="8sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
<View
android:id="#+id/vLine2"
android:layout_width="50dp"
android:layout_height="1dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#000000"
app:layout_constraintBottom_toBottomOf="#+id/civSprite"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/civSprite"
app:layout_constraintTop_toTopOf="#+id/civSprite">
</View>
<TextView
android:id="#+id/txtPokemonName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="Pokéball"
android:textAlignment="center"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<de.hdodenhof.circleimageview.CircleImageView
android:id="#+id/civSprite"
android:layout_width="148dp"
android:layout_height="148dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
android:src="#mipmap/ic_launcher"
app:civ_border_width="2dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/txtPokemonName" />
<View
android:id="#+id/vLine"
android:layout_width="50dp"
android:layout_height="1dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#000000"
app:layout_constraintBottom_toBottomOf="#+id/civSprite"
app:layout_constraintEnd_toStartOf="#+id/civSprite"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/civSprite">
</View>
<ImageView
android:id="#+id/imgIsRaidBoss"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toTopOf="#+id/vLine2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/civSprite"
app:srcCompat="#drawable/raid_sprite" />
<ImageView
android:id="#+id/imgShinyExists"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_marginBottom="4dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toTopOf="#+id/imgIsRaidBoss"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/civSprite"
app:srcCompat="#drawable/ic_shiny" />
<android.support.constraint.ConstraintLayout
android:id="#+id/cLayTypTwo"
android:layout_width="50dp"
android:layout_height="25dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:background="#drawable/customborder_typ"
app:layout_constraintBottom_toTopOf="#+id/vLine"
app:layout_constraintEnd_toStartOf="#+id/civSprite"
app:layout_constraintStart_toStartOf="parent">
<TextView
android:id="#+id/txtTypTwo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView"
android:textColor="#FFFFFF"
android:textSize="8sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
<Button
android:id="#+id/btnPokeDexEnty"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="48dp"
android:layout_marginStart="48dp"
android:layout_marginTop="16dp"
android:background="#drawable/boarder_shape"
android:text="Pokédex Eintrag"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/civSprite" />
<TextView
android:id="#+id/txtPokeDexEntry"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="TextView"
android:textAlignment="center"
android:visibility="gone"
app:layout_constraintEnd_toEndOf="#+id/btnPokeDexEnty"
app:layout_constraintStart_toStartOf="#+id/btnPokeDexEnty"
app:layout_constraintTop_toBottomOf="#+id/btnPokeDexEnty" />
<android.support.v7.widget.RecyclerView
android:id="#+id/rViewPokeInfo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
android:foregroundGravity="center_vertical"
android:orientation="vertical"
android:textAlignment="center"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/txtPokeDexEntry" />
</android.support.constraint.ConstraintLayout>
gridview_pokedex_pokeinfo.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/rLayMainContainer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:gravity="center"
android:orientation="vertical">
<TextView
android:id="#+id/txtPokeInfoTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:text="TextView"
android:textStyle="bold" />
<TextView
android:id="#+id/txtPokeInfoText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/txtPokeInfoTitle"
android:layout_centerHorizontal="true"
android:text="TextView" />
</RelativeLayout>
recyclerview code
RecyclerView recyclerViewPokeInfo = (RecyclerView)rLayout_mainFragment.findViewById(R.id.rViewPokeInfo);
RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getActivity(),2);
recyclerViewPokeInfo.setLayoutManager(layoutManager);
CustomRecyclerAdapterPokeInfoGrid adapter = new CustomRecyclerAdapterPokeInfoGrid(getActivity(), db.getPokeInfo(intPokemonID));
recyclerViewPokeInfo.setAdapter(adapter);
recyclerview adapter
package com.spicysoftware.goexpert;
import android.content.Context;
import android.support.constraint.ConstraintLayout;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.ArrayList;
public class CustomRecyclerAdapterPokeInfoGrid extends RecyclerView.Adapter<CustomRecyclerAdapterPokeInfoGrid.ViewHolder> {
private final ArrayList<String> strPokeInfo;
private Context context;
MySQLiteHelper db;
int locationSpriteNo;
String strCatchRate = "";
String strEscapeRate = "";
String strInEggs = "";
String strKmAsFriend = "";
public CustomRecyclerAdapterPokeInfoGrid(Context context, ArrayList<String> strPokeInfo) {
this.strPokeInfo = strPokeInfo;
this.context = context;
}
#Override
public CustomRecyclerAdapterPokeInfoGrid.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.gridview_pokedex_pokeinfo, viewGroup, false);
return new ViewHolder(view);
}
#Override
public void onBindViewHolder(final CustomRecyclerAdapterPokeInfoGrid.ViewHolder viewHolder, final int i) {
viewHolder.setClickListener(new ItemClickListener() {
#Override
public void onClick(View view, int position, boolean isLongClick) {
}
});
// load image
try {
db = new MySQLiteHelper(context);
String currentString = strPokeInfo.get(i);
if(i == 0){
viewHolder.txtPokeInfoTitle.setText("Fangchance");
}else if(i == 1){
viewHolder.txtPokeInfoTitle.setText("Fluchtchance");
}else if(i == 2){
viewHolder.txtPokeInfoTitle.setText("In Eiern");
}else if(i == 3){
viewHolder.txtPokeInfoTitle.setText("Distanz als Kumpel");
}
viewHolder.txtPokeInfoText.setText(currentString);
}
catch(Exception ex) {
Log.v("Error: ", "-> "+ex);
}
}
#Override
public int getItemCount() {
return strPokeInfo.size();
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener{
private TextView txtPokeInfoTitle,txtPokeInfoText;
private ItemClickListener clickListener;
private ConstraintLayout cLayoutSingleItem;
public ViewHolder(View view) {
super(view);
txtPokeInfoTitle = (TextView)view.findViewById(R.id.txtPokeInfoTitle);
txtPokeInfoText = (TextView)view.findViewById(R.id.txtPokeInfoText);
cLayoutSingleItem = (ConstraintLayout)view.findViewById(R.id.cLayoutSingleItem);
itemView.setOnClickListener(this);
itemView.setOnLongClickListener(this);
}
public void setClickListener(ItemClickListener itemClickListener) {
this.clickListener = itemClickListener;
}
#Override
public void onClick(View view) {
clickListener.onClick(view, getPosition(), false);
}
#Override
public boolean onLongClick(View view) {
clickListener.onClick(view, getPosition(), true);
return true;
}
}
}

Set the list item layout to match_parent like this:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/rLayMainContainer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:gravity="center"
android:orientation="vertical">
<TextView
android:id="#+id/txtPokeInfoTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:text="TextView"
android:textStyle="bold" />
<TextView
android:id="#+id/txtPokeInfoText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/txtPokeInfoTitle"
android:layout_centerHorizontal="true"
android:text="TextView" />
</RelativeLayout>

Try setting layout_gravity in your textViews instead of the relativeLayout.

ListView is jumping out of screen after touching EditText

I'm making a simple ToDo-List app to learn how to develop Android apps. First, I had an EditText, a normal Button and a ListView. Everything was fine, I could add and delete tasks. Than I wanted to replace the Button with an ImageButton. I made the same constraints. Now, as soon as I touch the EditText, my ListView is jumping up and out of the screen, but a part of it is still on the screen covering my ImageButton, so I can't use it anymore. But if I press "Ok" on the Soft Keyboard, the ListView is jumping back, and than I can use the ImageButton again to add the task. What am I doing wrong?
activity-main.xml:
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
android:id="#+id/editText"
android:layout_width="255dp"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:ems="10"
android:hint="#string/editTextHint"
android:inputType="textPersonName"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageButton
android:id="#+id/addButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:contentDescription="#string/addTaskButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toEndOf="#+id/editText"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#android:drawable/ic_input_add" />
<ListView
android:id="#+id/listView"
android:layout_width="365dp"
android:layout_height="428dp"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/editText" />
MainActivity.java:
ListView lv;
ArrayList<Task> taskList;
TaskArrayAdapter taskAdapter;
EditText editText;
ImageButton btn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = findViewById(R.id.listView);
editText = findViewById(R.id.editText);
btn = findViewById(R.id.addButton);
taskList = new ArrayList<>();
handleButton();
taskAdapter = new TaskArrayAdapter(taskList, this);
}
public void handleButton() {
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
editText.onEditorAction(EditorInfo.IME_ACTION_DONE);
taskList.add(new Task(editText.getText().toString()));
lv.setAdapter(taskAdapter);
taskAdapter.notifyDataSetChanged();
editText.setText(null);
}
});
}
#Override
public void onCheckedChanged(CompoundButton checkedTask, boolean isChecked) {
int position = lv.getPositionForView(checkedTask);
Task t = taskList.get(position);
t.setSelected(isChecked);
taskList.remove(t);
lv.setAdapter(taskAdapter);
taskAdapter.notifyDataSetChanged();
}
}
Yeah, I'm new to coding in general, so just let me know, if I made some other mistakes. Thank you :)

<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="#+id/et_task"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toStartOf="#+id/btn_add"
android:hint="Enter task"
/>
<Button
android:id="#+id/btn_add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="+"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
/>
<ListView
android:layout_width="match_parent"
android:layout_height="100dp"
app:layout_constraintTop_toBottomOf="#+id/et_task"
app:layout_constraintEnd_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
/>
</android.support.constraint.ConstraintLayout>

list view show only 10 items

I would like to implement a method that allows me to implement a listview with 2 different String-array from from strings.xml.
My code works but my phone can only show the first 10 items. where is my problem? I f I try to run the code on a virtual device it works correctly.
Here is my code with only one textview. (this one shows only the first 10 items)
Button btt_backHome;
ListView lV_titoli;
EditText eT_search;
private ArrayAdapter<CharSequence> adapter , adapter_testi;
ImageView img_titoli;
List<RowData> rowData;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_titoli);
img_titoli = (ImageView) findViewById(R.id.img_titoli); // Create an icon
Picasso.get().load(R.drawable.sfondo).resize(2048, 1356).centerInside().into(img_titoli);
btt_backHome = (Button) findViewById(R.id.btt_backHome);
lV_titoli = (ListView) findViewById(R.id.lV_titoli);
eT_search = (EditText) findViewById(R.id.eT_search);
//serve per nascondere la tastiera
this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
adapter = ArrayAdapter.createFromResource(this, R.array.titoli, android.R.layout.simple_list_item_1);
lV_titoli.setAdapter(adapter);
adapter.getFilter().filter("");
final Intent refresh = new Intent(this, activity_titoli.class);
final Intent to_Home = new Intent (this , Activity_Main.class);
final Intent to_Canzone_from_titoli = new Intent (this , activity_canzone.class);
eT_search.addTextChangedListener(new TextWatcher() {
#Override
public void afterTextChanged(Editable arg0) {
// TODO Auto-generated method stub
}
#Override
public void beforeTextChanged(CharSequence arg0, int arg1,
int arg2, int arg3) {
// TODO Auto-generated method stub
}
#Override
public void onTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
(activity_titoli.this).adapter.getFilter().filter(arg0);
}
});
btt_backHome.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(to_Home);
}
});
lV_titoli.setOnItemClickListener(new AdapterView.OnItemClickListener(){
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Resources res = getResources();
List<String> list = Arrays.asList(res.getStringArray(R.array.titoli));
to_Canzone_from_titoli.putExtra("riga", list.indexOf(adapter.getItem(i)));
startActivity(to_Canzone_from_titoli);
}
});
}
And this is my xml code:
<ImageView
android:id="#+id/img_titoli"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:alpha="1"
android:scaleType="fitXY"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/btt_backHome"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="16dp"
android:layout_marginTop="8dp"
android:text="indietro"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<android.support.constraint.Guideline
android:id="#+id/guideline2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_begin="20dp" />
<EditText
android:id="#+id/eT_search"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="64dp"
android:ems="10"
android:hint="Ricerca..."
android:inputType="textPersonName"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="128dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ListView
android:id="#+id/lV_titoli"
android:layout_width="match_parent"
android:layout_height="500dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</LinearLayout>
</ScrollView>

<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="128dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ListView
android:id="#+id/lV_titoli"
android:layout_width="match_parent"
android:layout_height="500dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</LinearLayout>
</ScrollView>
this is the problem. you have a listview nested inside a scroll view. you dont need to do that as a listview itsself scrolls. try this in place of that whole thing:
<ListView
android:id="#+id/lV_titoli"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="128dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
</ListView>

Your problem is so straightforwardly simple: You don't have to put ListView in ScrollView to make it able to scroll, because ListView has its own class implementation of scrolling.
Delete this tag:
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="128dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
</ScrollView>
And keep it like that:
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ListView
android:id="#+id/lV_titoli"
android:layout_width="match_parent"
android:layout_height="500dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</LinearLayout>
If you wish to dig deeper, please check this question:
ListView inside ScrollView is not scrolling on Android
Good Luck!

Develop Reference

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