Develop Reference

Adding views programatically to a relative layout within a scrollview

Please bear with me as I am new to the use of Views and Layouts.
I am trying to create an application in which the user can enter a text field, press a button and have a new text field appear and they can continue adding text fields in this way.
My solution was to have the top level be a scrollview and then have a relative view as a child within that(this way I can then programatically insert more editviews in my code with the OnClick() listener.
I have seen and read a couple of other posts pertaining to relative views but it seems there is still something that I am missing. I have tried
Here is the xml
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/activity_create_accounts"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.nic.mybudget.CreateAccountsActivity">
<RelativeLayout
android:id="#+id/activity_create_accounts_relativeLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fillViewport="true"
>
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/activity_name"
android:inputType="textAutoComplete"
android:layout_alignParentTop="true"
android:id="#+id/activity_createAccounts_relativeLayout_activityName"/>
<Button
android:text="+"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_below="#+id/activity_createAccounts_relativeLayout_activityName"
android:id="#+id/activity_create_accounts_relativeLayout_activityName_addButton" />
<Button
android:text="Save"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_below="#+id/activity_create_accounts_relativeLayout_activityName_addButton"
android:layout_centerHorizontal="true"
android:id="#+id/activity_create_accounts_relativeLayout_activityName_saveButton" />
</RelativeLayout>
And here is the Code where I try to add new editviews.
public class CreateAccountsActivity extends Activity {
static private final String TAG = "MAIN-Activity";
int numAccounts = 0;
int lastAccountID;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_create_accounts);
final RelativeLayout Relative = (RelativeLayout) findViewById(R.id.activity_create_accounts_relativeLayout);
final TextView oldAccount = (TextView) findViewById(R.id.activity_createAccounts_relativeLayout_activityName);
final TextView newAccount = new TextView(this);
final Button addNewAccountButton = (Button) findViewById(R.id.activity_create_accounts_relativeLayout_activityName_addButton);
addNewAccountButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Log.i(TAG, "addNewAccountOnClick");
numAccounts = numAccounts+1;
int newAccountID = oldAccount.getId() + numAccounts;
RelativeLayout.LayoutParams rlp = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);
rlp.addRule(RelativeLayout.ALIGN_PARENT_TOP);
newAccount.setLayoutParams(rlp);
newAccount.setHint("Hint" );
newAccount.setId(newAccountID);
Relative.addView(newAccount);
RelativeLayout.LayoutParams blp = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT);
blp.addRule(RelativeLayout.BELOW, newAccountID-1);
addNewAccountButton.setLayoutParams(blp);
}
});
}
}
As you can see what I am trying (and failing) to do is add the new edit view at the top of the page and simply push everything else down the page. What am I getting wrong here with the relative layout?
Any help is appreciated.

First thing View with id activity_createAccounts_relativeLayout_activityName is EditText and you are casting it with TextView so that is wrong cast it to EditText.
And to your actual problem:
You are using same EditText instance with variable newAccount and adding it again in relative layout if you want to add one more EditText in relative layout you have to initialise EditText inside onclicklistener.
Just add one line newAccount= new EditText(context)in your onclicklistener code before line numAccounts = numAccounts+1;
Happy Coding !

Connecting xml to programmatic layout in Android

I have a custom layout java file that I create and add views to like this:
PredicateLayout layout = new PredicateLayout(this);
for (int i = 0; i < someNumberThatChangesEveryTime; i++)
{
TextView t = new TextView(this);
t.setText("Hello");
t.setBackgroundColor(Color.RED);
t.setSingleLine(true);
layout.addView(t, new PredicateLayout.LayoutParams(2, 0));
}
setContentView(layout);
What I would like to do is define my TextView in an xml, so I can add it like so:
TextView t = (TextView) findViewById(R.id.textview);
And of couse also add other kinds of views. I have no idea how to write this xml file, or how to connect it to this activity. The layout I'm using is this one: Line-breaking widget layout for Android

Find the id of the root layout in xml and add other ui elements programatically to the root layout.
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
andorid:id="#+id/ll
tools:context=".MainActivity" >
<TextView
android:id="#+id/tv"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="20dp"
android:text="Blank text" />
</RelativeLayout>
Your MainActivity
public class MainActivity extends Activity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RelativeLayout ll = (RelativeLayout) findViewById(R.id.ll);
TextView tv= (TextView) findViewById(R.id.tv);
// add other ui elements to the root layout ie Relative layout
}
}

Android: dynamically set the position of button into center of screen in RelativeLayout

There has been many questions on dynamically setting the position of a button, but I just want to change the position of a button into center of the screen. My layout is RelativeLayout.
Updated:
At the beginning, myButton has been set position in XML as:
<Button
android:id="#+id/myButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:text="Menu" />
Any suggestion would be greatly appreciated

See an example below (click the button and it will be moved to the center).
activity_main.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/root"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Button
android:id="#+id/my_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:text="Menu" />
</RelativeLayout>
MainActivity.java:
public class MainActivity extends Activity {
private View mView;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mView = findViewById(R.id.my_view);
mView.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
ViewGroup.LayoutParams vg_lp = mView.getLayoutParams();
// Make sure we are in RelativeLayout
if (vg_lp instanceof RelativeLayout.LayoutParams) {
RelativeLayout.LayoutParams rl_lp = new RelativeLayout.LayoutParams(vg_lp);
rl_lp.addRule(RelativeLayout.CENTER_IN_PARENT);
mView.setLayoutParams(rl_lp);
}
}
});
}
}

Try:
......
RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) button.getLayoutParams();
layoutParams.leftMargin = parentLayout.getWidth()/2;
layoutParams.topMargin = parentLayout.getHeight()/2;
button.setLayoutParams(layoutParams);
......

Try this one:
RelativeLayout RL = (RelativeLayout)findViewById(R.id.relative_layout);
RL.gravity(Gravity.CENTER);
with this all subviews of RL will be in center;
Button anyButton = new Button(this);
RL.addSubview(anyButton);//this genereted button will be in center as well

Try this,
RelativeLayout my_layout = new RelativeLayout(this);
my_layout.setId(some_value);
Button my_btn = new Button(this);
RelativeLayout.LayoutParams my_params = new RelativeLayout.LayoutParams(btn_height,btn_width);
my_params.addRule(RelativeLayout.CENTER_IN_PARENT,my_layout.getId());
my_layout.addView(my_btn,my_params);

Add this 2 lines to the component you want to center in the xml file :
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"

How to add a button control to an android xml view at runtime?

I have an android xml layout, main.xml. I would like to add controls to this layout at runtime (I would like to add a series of additional linear layouts that contain buttons controls). Can I do that and if yes, how?
Thanks

I see the error u r doing here
LinearLayout mainLayout = (LinearLayout) findViewById(R.layout.main);
You r taking the layout as Linearlayout object, you should take the LinearLayout id
Try this
LinearLayout lnr = (LinearLayout) findViewById(R.id.LinearLayout01);
Button b1 = new Button(this);
b1.setText("Btn");
lnr.addView(b1);

You can add controls programmatically if you want in your code, or even another XML with a View and an Inflater.
Here you can read the basics: http://developer.android.com/guide/topics/ui/declaring-layout.html

Ok, I have got it to work.
The steps are the following:
First inflate the xml layout, ie,
View view = View.inflate(this, R.layout.main, null);
Then instantiate the container object from the xml layout into a ViewGroup class, ie,
ViewGroup container = (ViewGroup) view.findViewById(R.id.myContainer);
Then create a linearLayout object, create and add onto that any controls needed, add the linearLayout to the container object and use setContentView on the view object, ie,
container.addView(buttonsLayout);
this.setContentView(view);

You can do this quite easy by setting an id on the layout on which you want to add views to. Say your main.xml look like this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView android:id="#+id/label"
android:layout_width="fill_parent"/>
<LinearLayout android:id="#+id/container"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
</LinearLayout>
</LinearLayout>
Lets assume that you want to add your additional views to the LinearLayout with id id/container. In your onCreate method you could retrieve that object for later use:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mContainer = (ViewGroup)view.findViewById(R.id.container);
}
Now you are all set to add other views to your container ViewGroup:
LinearLayout theButtons = getButtons()
mContainer.addView(theButtons);
In the getButtons method you need to create your LinearLayout containing the buttons you need. Either you do this programmatically or by inflating a view defined in an XML file. See LayoutInflater.inflate.

just try this:
LinearLayout mainLinearLayout = (LinearLayout) findViewById(R.layout.llmain);
now create button dynamically like this
Button btn1 = new Button(this);
btn1.setText=("Button 1");
mainLinearLayout .addView(btn1);
now if you want to add onether linearlayout then add it below button then
LinearLayout llinner = new LinearLayout(this);
Button btn2 = new Button(this);
btn2.setText=("Button 2");
mainLinearLayout .addView(btn2);
llinner.addView(btn2 );
mainLinearLayout .addView(llinner);

Try this :
LinearLayout ll =(LinearLayout)findViewById(R.id.linlay);
Button b = new Button(this);
b.setText("Hello");
l.addView(b);
This might help you

Here is what I did to display a set of runtime buttons on table layout.
MainActivity.java
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
View view = View.inflate(this, R.layout.activity_main, null);
TableRow myrow = (TableRow) view.findViewById(R.id.myrow);
Button btn1 = new Button(this);
btn1.setText("Button 1");
myrow .addView(btn1);
Button btn2 = new Button(this);
btn2.setText("Button 2");
myrow .addView(btn2);
this.setContentView(view);
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ScrollView
android:id="#+id/myview"
android:layout_width="404dp"
android:layout_height="691dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TableLayout
android:id="#+id/mylayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TableRow android:id="#+id/myrow"></TableRow>
</TableLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
AVD Pixel4API30
Output screenshot

Android:Drawing Many Text Views

I'm new to android platform , I'd like to settext using textviews , I tried to write set text into two textviews but its just draws one textview why?
I can't draw two textviews
TextView tv1;
TextView tv2;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
layout = new LinearLayout(this);
tv1 = new TextView(this);
tv2 = new TextView(this);
tv1.setText("Hello");
tv2.setText("How are you?");
}

On Android, the user interface normally should be created using XML-files, instead of Java code. You should read up on the tutorials on android.com, especially:
http://developer.android.com/guide/topics/ui/declaring-layout.html
An example:
In your res/layout/main.xml, you define the text TextView's:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView android:id="#+id/TextView1" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="TextView 1"/>
<TextView android:id="#+id/TextView2" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="TextView 2"/>
</LinearLayout>
Then if you use setContentView in the activity to display this, the app will show to TextView's:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.main);
}
If you want to programmatically set the text in the Activity, just use findViewById():
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContentView(R.layout.main);
((TextView)this.findViewById(R.id.TextView1)).setText("Setting text of TextView1");
}

I definitely second TuomasR's suggestion to use XML layouts. However, if you're wanting to add new TextViews dynamically (i.e. you don't know how many you will need until runtime), you need to do a couple of other steps to what you are doing:
First, define your LinearLayout in main.xml (it's just easier that way than LayoutParams, IMO):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/my_linear_layout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
/>
Now, you can go to your code, and try the following:
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
//This inflates your XML file to the view to be displayed.
//Nothing exists on-screen at this point
setContentView(R.layout.main);
//This finds the LinearLayout in main.xml that you gave an ID to
LinearLayout layout = (LinearLayout)findViewById(R.id.my_linear_layout);
TextView t1 = new TextView(this);
TextView t2 = new TextView(this);
t1.setText("Hello.");
t2.setText("How are you?");
//Here, you have to add these TextViews to the LinearLayout
layout.addView(t1);
layout.addView(t2);
//Both TextViews should display at this point
}
Again, if you know ahead of time how many views that you need, USE XML.