Develop Reference

Saving the editText without using a save button, app stops working

I want to be able to store the contents of the editText input, then be able to display it in a listview.
I have connected a RFID device that is set in emulator mode. This mode basically also you to scan an RFID tag and the RFID number gets populated where ever the mouse cursor is. In this case it is at the editText input. The lenght of the RFID number is 10, since the RFID number as 10 digits. Once the RFID number is detected I then want to display it on the listview and scan another tag and add that to the listview also.
In my case whenever I code sees the display method the app crashes and I dont know why. Can someone explain to me why this is happening?
epc.add("\n" + etRfidNo.getText().toString() + ", " + DateFormat.getInstance().format(currentDate));
display();```
MainActivity code:
public class MainActivity extends AppCompatActivity {
EditText etRfidNo;
TextView textView;
private Set<String> epc = new HashSet<>();
ArrayAdapter<String> contactAdapter;
String single_epc;
Button scan;
ListView listView;
boolean set = true;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView)findViewById(R.id.textView);
etRfidNo = (EditText) findViewById(R.id.etRfidNo);
scan = (Button) findViewById(R.id.scan);
TextView textV = (TextView)findViewById(R.id.textView);
etRfidNo.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
//TextView textV = (TextView)findViewById(R.id.textView);
//textV.setText(s); //set text for text view
single_epc = String.valueOf(s);
if(s.length() == 10)
{
Date currentDate = new Date();
epc.add("\n" + etRfidNo.getText().toString() + ", " + DateFormat.getInstance().format(currentDate));
display();
}
}
#Override
public void afterTextChanged(Editable s) {
}
});
}
public void display() {
contactAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, new ArrayList<>(epc));
listView.setAdapter(contactAdapter);
}
}

listView = (ListView) findViewById(R.id.listviewID);
Forgot to add this.

How to change the background of many images when user entered a text in EditText in Android

I have a program that has 10 images. I want to change the background of each image when the user enters valid text in editText. So basically if user enters valid text in the editText it will change the first image (image 1). If the user enters text again in editText it should change image 2 etc. until image 10.
I have tried to create a list of images and retrieve every element in the image.
I don't know if my logic is wrong
The images are stamp1, stamp2, stamp3, stamp4 ....stamp12
final String Entercode = codeNumber.getEditableText().toString().trim();
Toast.makeText(getApplicationContext(),Entercode,Toast.LENGTH_SHORT).show();
if (Entercode.equals("sweet")){
for (int i = 0; i < stampImageList.size(); i++) {
Object obj = stampImageList.get(i);
stampImageList = new ArrayList();
stampImageList.add(stamp1);
stampImageList.add(stamp2);
stampImageList.add(stamp3);
stampImageList.add(stamp4);
stampImageList.add(stamp5);
stampImageList.add(stamp6);
stampImageList.add(stamp7);
stampImageList.add(stamp8);
stampImageList.add(stamp9);
stampImageList.add(stamp10);
stampImageList.add(stamp11);
stampImageList.add(stamp12);
if (obj == stampImageList.get(2)) {
// stamp4.setBackgroundResource(R.drawable.earned_stamp);
stamp3.setBackgroundResource(R.drawable.earned_stamp);
AlertDialog.Builder builder = new AlertDialog.Builder(getApplicationContext());
builder.setIcon(R.drawable.logo);
builder.setMessage("Stamp Earned");
} else if (obj == stampImageList.get(3)) {
stamp5.setBackgroundResource(R.drawable.earned_stamp);
AlertDialog.Builder builder = new AlertDialog.Builder(getApplicationContext());
builder.setIcon(R.drawable.logo);
builder.setMessage("Stamp Earned");
}
}
} else{
AlertDialog.Builder alert = new AlertDialog.Builder(getApplicationContext());
alert.setIcon(R.drawable.logo);
alert.setTitle("Validation results");
alert.setMessage("validation failed");
}

You should use TextWatcher to EditText.In afterchange method you compare with values.
EditText et = (EditText)findViewById(R.id.editText);
Log.e("TextWatcherTest", "Set text xyz");
et.setText("xyz");
et.addTextChangedListener(new TextWatcher() {
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) { }
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) { }
#Override
public void afterTextChanged(Editable s) {
Log.e("TextWatcherTest", "afterTextChanged:\t" +s.toString());//Compare here with stamp1 or like that
}
});

#steve, here I have prepared a code for 10 Drawable Images in your project.
public class Pictures_Activity_stack extends AppCompatActivity {
private String TAG= "Pictures_Activity---";
private ImageView picture;
private EditText text;
private Button validate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pictures_stack);
picture = (ImageView)findViewById(R.id.picture); //imageview where your picture changes
text = (EditText) findViewById(R.id.text);//edittext where you input text
validate = (Button) findViewById(R.id.button);//button to validate the text and change picture accordingly
// array to store your drawable images
final int pictures[] = {
R.drawable.firstimage,
R.drawable.secondimage,
R.drawable.p3,
R.drawable.p4,
R.drawable.p5,
R.drawable.p6,
R.drawable.p7,
R.drawable.p8,
R.drawable.p9,
R.drawable.p10
};
// click the button to set the image
validate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String input = text.getText().toString(); //input from edittext
if (input.equals("first")) {
picture.setImageResource(pictures[0]); //set first image in array if input=first
Toast.makeText(getBaseContext(),input,Toast.LENGTH_SHORT).show();
}
else if (input.equals("second")) {
picture.setImageResource(pictures[1]);//set first image in array if input=secind
Toast.makeText(getBaseContext(),input,Toast.LENGTH_SHORT).show();
}
// else if (input.equals("third")) {
// // and so on for other string values...
// .................................
// }
else
{
// if your input does not matches any string do this
Toast.makeText(getBaseContext(),"NO MATCHED STRING",Toast.LENGTH_SHORT).show();
}
}
});
}
}
The above code set images according to input in edit Text, when button is clicked.

Substraction between Float

Please guys help me! I'm going crazy ! Below is a brief summary of my code that should be used to make a simple subtraction . Should I just read the amount of SCONTRINO and if you put CONTANTI , the field VINCITE , will have as setText SCONTRINO - CONTANTI , same with VINCITE , will CONTANTI.setText SCONTRINO - VINCITE .
But despite everything seems to be well written , when I insert a field , I StackOverflowError by the two Update methods.
public class AssegnaScontoActivity extends Activity {
TextView contanti;
TextView vincite;
TextView scontrino;
Float contantiFloat;
Float vinciteFloat;
Float scontrinoFloat;
public void onCreate(Bundle savedInstanceState) {
//INIZIALIZZAZIONE ACTIVITTY
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN);
super.onCreate(savedInstanceState);
setContentView(R.layout.assegna_sconto_activity_landscape);
//--------------------------
contantiFloat = Float.parseFloat(contanti.getText().toString());
vinciteFloat = Float.parseFloat(vincite.getText().toString());
scontrinoFloat = Float.parseFloat(1000);
contanti = (TextView) findViewById(R.id.contanti);
vincite = (TextView) findViewById(R.id.importo_vincite);
scontrino = (TextView) findViewById(R.id.importo_scontrino);
contanti.addTextChangedListener(new TextChangedListener()
{
#Override
public void numberEntered(Float number)
{
contantiFloat = number;
updateVincite();
}
});
vincite.addTextChangedListener(new TextChangedListener()
{
#Override
public void numberEntered(Float number)
{
vinciteFloat = number;
updateContanti();
}
});
}
private void updateVincite()
{
Float total = scontrinoFloat - contantiFloat; // This is where you apply your function
vincite.setText(""+total); // need to do that otherwise int will
// be treated as res id.
}
private void updateContanti()
{
Float total = scontrinoFloat - vinciteFloat; // This is where you apply your function
contanti.setText(""+total); // need to do that otherwise int will
// be treated as res id.
}
private abstract class TextChangedListener implements TextWatcher
{
public abstract void numberEntered(Float number);
#Override
public void afterTextChanged(Editable s)
{
String text = s.toString();
try
{
Float parsedFloat = Float.parseFloat(text);
numberEntered(parsedFloat);
} catch (NumberFormatException e)
{
Log.w(getPackageName(), "Non si puo' parsare '" + text + "' col numero", e);
}
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count, int after)
{
}
#Override
public void onTextChanged(CharSequence s, int start, int before, int count)
{
}
}

Your code is going into an infinite loop because you are changing the text when afterTextChanged() is called, which causes afterTextChanged() to be called again and so on until eventually you overflow your call stack.
You can stop this by only setting the text inside updateVincite() and updateContanti() if it is different to the current text.
e.g.:
private void updateVincite()
{
Float total = scontrinoFloat - contantiFloat; // This is where you apply your function
String text = ""+total;
if(!vincite.getText().toString().contentEquals(text))
vincite.setText(text); // need to do that otherwise int will
// be treated as res id.
}
and do the same for updateContanti()

First define contanti and vincite .
Change code as follows.
contanti = (TextView) findViewById(R.id.contanti);
vincite = (TextView) findViewById(R.id.importo_vincite);
scontrino = (TextView) findViewById(R.id.importo_scontrino);
contantiFloat = Float.parseFloat(contanti.getText().toString());
vinciteFloat = Float.parseFloat(vincite.getText().toString());
scontrinoFloat = Float.parseFloat(1000);

.setText not working properly

So I'm in a basic part of my application I'm wanting to make. I've never gotten this error before, and I don't know what's going on. My .setText is throwing an error saying "setText cannot be resolved or is not a field" I've looked around and haven't been able to find my problem. I believe I'm doing it correctly. If anyone could help me out that'd be great!
MainActivity.java:
public class MainActivity extends Activity {
final TextView loading_Text = (TextView)findViewById(R.id.textView4);
final EditText name_Edit = (EditText)findViewById(R.id.editText1);
//String Values
String Age="";
String Name = name_Edit.getText().toString();
//Int Values
int Gender = 0; //1 male | 2 female
int Group = 0; //Different groups for ages and genders
int save_Info = 0; //save info to phone
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button male_Button= (Button)findViewById(R.id.button1);
Button female_Button = (Button)findViewById(R.id.button2);
male_Button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
Gender++;//Adds one to show this user is a male.
loading_Text.setText=(Name);
}
});
}

I saw two problems:
First:
loading_Text.setText=(Name);
Should be
loading_Text.setText("The text you want to set");
You'll need to take a look at the API document to see how to call the method.
Second:
Move these part:
final TextView loading_Text = (TextView)findViewById(R.id.textView4);
final EditText name_Edit = (EditText)findViewById(R.id.editText1);
//String Values
String Age="";
String Name = name_Edit.getText().toString();
inside your onCreate, like this:
public class MainActivity extends Activity {
TextView loading_Text;
EditText name_Edit;
...
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
loading_Text = (TextView)findViewById(R.id.textView4);
name_Edit = (EditText)findViewById(R.id.editText1);
Or you'll get NullPointerException.
This is because you were trying to reach the View's property before the view is being initialized. View will be initialized after setContentView, and what you were intend to do was findViewById from R.layout.activity_main before it had been loaded.
Similarly, you'll need to move this call of method:
String Name = name_Edit.getText().toString();
somewhere after setContentView.

setText is a function. So you would need to pass name as a argument.
like loading_Text.setText(Name);

Change
loading_Text.setText=(Name);
to this:
loading_Text.setText(Name);
Also, if you don't see anything in the textview, it is because you are getting the edittext's text before you even create your views, I use an on edittext listener like this to refresh the String when the edit text is changed:
name_Edit.addTextChangedListener(new TextWatcher() {
public void afterTextChanged(Editable s) {
Name = name_Edit.getText().toString();
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
public void onTextChanged(CharSequence s, int start, int before, int count) {}
});
I hope this works for you :)

Possible to initialize all UI elements in one method?

Is it possible to initialize all UI elements of certain type (like all TextViews or all LineraLayouts or ...) in a some kind of loop?
I have many layouts with a lot of the elements of the same type and it's really painful to do it all just by typing.

You can use RoboGuice .It doesn't use loops, but helps you to Inject your View, Resource, System Service, or any other object in to your code.
RoboGuice is a framework that brings the simplicity and ease of Dependency Injection to Android, using Google's own Guice library.
To give you an idea, take a look at this simple example of a typical Android activity:
class AndroidWay extends Activity {
TextView name;
ImageView thumbnail;
LocationManager loc;
Drawable icon;
String myName;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
name = (TextView) findViewById(R.id.name);
thumbnail = (ImageView) findViewById(R.id.thumbnail);
loc = (LocationManager) getSystemService(Activity.LOCATION_SERVICE);
icon = getResources().getDrawable(R.drawable.icon);
myName = getString(R.string.app_name);
name.setText( "Hello, " + myName );
}
}
This example is 19 lines of code. If you're trying to read through onCreate(), you have to skip over 5 lines of boilerplate initialization to find the only one that really matters: name.setText(). And complex activities can end up with a lot more of this sort of initialization code.
Compare this to the same app, written using RoboGuice:
class RoboWay extends RoboActivity {
#InjectView(R.id.name) TextView name;
#InjectView(R.id.thumbnail) ImageView thumbnail;
#InjectResource(R.drawable.icon) Drawable icon;
#InjectResource(R.string.app_name) String myName;
#Inject LocationManager loc;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
name.setText( "Hello, " + myName );
}
}
In this example, onCreate() is much easier to take in at a glance. All the platform boilerplate is stripped away and you're left with just your own app's business logic. Do you need a SystemService? Inject one. Do you need a View or Resource? Inject those, too, and RoboGuice will take care of the details.
RoboGuice's goal is to make your code be about your app, rather than be about all the initialization and lifecycle code you typically have to maintain in Android.
This text is from here

I have/had done something similar. Just for your reference, here's the code:
public class AbcActivity extends Activity
{
protected boolean changesPending;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.login_screen);
setViews(); //this method is created and called to take care of the buttons and edittext fields, and can probably hold a number of other fields/widgets as well
}
/** Take care of the Buttons and EditTexts here*/
private void setViews()
{
EditText userEdit = (EditText)findViewById(R.id.editText1);
EditText passwordEdit = (EditText)findViewById(R.id.editText2);
Button loginButton = (Button)findViewById(R.id.login_button);
loginButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
login(); // some random method
}
});
Button cancelButton = (Button)findViewById(R.id.cancel_button);
cancelButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
cancel(); //another random method
}
});
userEdit.addTextChangedListener(new TextWatcher()
{
public void onTextChanged(CharSequence s, int start, int before, int count)
{
changesPending = true;
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
public void afterTextChanged(Editable s) {}
});
passwordEdit.addTextChangedListener(new TextWatcher()
{
public void onTextChanged(CharSequence s, int start, int before, int count)
{
changesPending = true;
}
public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
public void afterTextChanged(Editable s) {}
});
}
}
Hope this helps.

If you are trying to handle a large number of Views it may be worthwhile handling creation of these Views at runtime, attaching them to the relevant container. For example:
ViewGroup container = (ViewGroup) findViewById(R.id.container);
for(int i = 0; i < NUM_TEXT_VIEWS; i++){
TextView tv = new TextView(this); // where 'this' is your Activity
tv.setText("This is TextView " + i);
container.addView(tv);
}
Properties set in your xml file for a View usually have a corresponding Java method call.