Android: programmatically adding buttons to a layout

Question

I'm trying to get an add button to add another button to the layout, based on the edittext to the left of the button. The point is for a person to list the rooms in their house, and then when they type in each room, a new button is generated so they can click the room, and then start working on the next page.

I had an xml layout all done, and then I realized I'm "programmatically" adding buttons, so I redid the layout programmatically, and then in the switch/case (that's how I do onclicks) for the add button I tried to add a button to the view, but it's getting very tricky. I'd like to have a scrollview below the edittext and add buttons, and as they add all the rooms to their house it eventually is populated with a scrollable list of buttons for their entire home. Is there a way to add buttons programmatically to an xml'd layout. I was thinking you can but everything I'm trying just isn't working.

Thanks for your help everybody, any recommendations you have would be greatly appreciated.

First Edit (in response to Tanuj's solution)

My XML file (not sure if we're going to use this or just use the java):

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical" >

<TextView
    android:id="@+id/tvAddARoom"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/tvAddARoom" />

<EditText
    android:id="@+id/etAddARoom"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="@string/etAddARoom" />


<Button
    android:id="@+id/btnAddARoom"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/btnAdd" />

<TextView
    android:id="@+id/tvSelectARoom"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/tvSelectARoom" />

<TextView
    android:id="@+id/tvNoRooms"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/tvNoRooms" />

<Button
    android:id="@+id/btnViewAll"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/btnViewAll" />

 </LinearLayout>

And the Java. This isn't at all correct, as in the java I'm creating the whole layout instead of using the layout above. Just not sure if I can bridge the two.

package com.bluej.movingbuddy;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
//import android.widget.ScrollView;
import android.widget.TextView;

public class EstimatorByRoom extends Activity implements OnClickListener {
String roomName;
EditText etAddARoom;
LinearLayout layout;
LinearLayout.LayoutParams layoutParam;


@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    //setContentView(R.layout.estimatorbyroom);

    LayoutParams params = 
            new LinearLayout.LayoutParams(
                    LayoutParams.FILL_PARENT,
                    LayoutParams.WRAP_CONTENT);

    //create a layout
    LinearLayout layout = new LinearLayout(this);
    layout.setOrientation(LinearLayout.VERTICAL);

    //create a text view
    TextView tvAddARoom = new TextView(this);
    tvAddARoom.setText("Add a Room");
    tvAddARoom.setLayoutParams(params);

    //create an edittext
    EditText etAddARoom = new EditText(this);
    etAddARoom.setHint("Living Room, Dining Room, etc.");
    etAddARoom.setLayoutParams(params);


    //create a button
    Button btnAddARoom = new Button(this);
    btnAddARoom.setText("Add");
    btnAddARoom.setLayoutParams(params);

    //adds the textview
    layout.addView(tvAddARoom);

    //add the edittext
    layout.addView(etAddARoom);
    //add the button
    layout.addView(btnAddARoom);

    //create the layout param for the layout
    LinearLayout.LayoutParams layoutParam = new LinearLayout.LayoutParams(
            LayoutParams.FILL_PARENT,
            LayoutParams.WRAP_CONTENT);

    this.addContentView(layout, layoutParam);
}

public void onClick(View v) {
    // TODO Auto-generated method stub
    switch (v.getId()) {

    case R.id.btnAddARoom:
        //add a room

        //this part isn't working!
        roomName = etAddARoom.getText().toString();
        Button createdButton = new Button(this);
        createdButton.setText(roomName);
        layout.addView(createdButton);
        this.addContentView(layout, layoutParam);

        //if no rooms make tvnorooms disappear

        break;
    }

}
}

Answer 1

Try this :

    //the layout on which you are working
    LinearLayout layout = (LinearLayout) findViewById(R.id.linear_layout_tags);

    //set the properties for button
    Button btnTag = new Button(this);
    btnTag.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
    btnTag.setText("Button");
    btnTag.setId(some_random_id);

    //add button to the layout
    layout.addView(btnTag);

Answer 2

Try this code:

LinearLayout l_layout = (LinearLayout) findViewById(R.id.linear_layout); 
l_layout.setOrientation(LinearLayout.VERTICAL); // or HORIZONTAL

Button btn1 = new Button(this);
btn1.setText("Button_text");

l_layout.addView(btn1);

btn1.setOnClickListener(new OnClickListener() {
     @Override
     public void onClick(View v) {
           // put code on click operation
     }
});

that is a way to create button dynamically and add in Layout.

remember that when you create button programmatically you just use this not Class_name.this

Answer 3

public class AndroidWalkthroughApp1 extends Activity implements View.OnClickListener {

    final int TOP_ID = 3;
    final int BOTTOM_ID = 4;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // create two layouts to hold buttons
        LinearLayout top = new LinearLayout(this);
        top.setId(TOP_ID);
        LinearLayout bottom = new LinearLayout(this);
        bottom.setId(BOTTOM_ID);

        // create buttons in a loop
        for (int i = 0; i < 2; i++) {
            Button button = new Button(this);
            button.setText("Button " + i);
            // R.id won't be generated for us, so we need to create one
            button.setId(i);

            // add our event handler (less memory than an anonymous inner class)
            button.setOnClickListener(this);

            // add generated button to view
            if (i == 0) {
                top.addView(button);
            }
            else {
                bottom.addView(button);
            }
        }

        // add generated layouts to root layout view
        LinearLayout root = (LinearLayout)this.findViewById(R.id.root_layout);
        root.addView(top);
        root.addView(bottom);
    }

    @Override
    public void onClick(View v) {
        // show a message with the button's ID
        Toast toast = Toast.makeText(AndroidWalkthroughApp1.this, "You clicked button " + v.getId(), Toast.LENGTH_LONG);
        toast.show();

        // get the parent layout and remove the clicked button
        LinearLayout parentLayout = (LinearLayout)v.getParent();
        parentLayout.removeView(v);
    }
}