Question

i have this android code .I have my layout for button defined in the xml file .i want to set the text for button here by getting it by id .but the app force closes.whats wrong ?

  package com.action ;
  import android.app.Activity;
  import android.os.Bundle;
  import android.widget.Button;

  public class ActionActivity extends Activity {
     @Override
     public void onCreate(Bundle i){
         super.onCreate(i);
         Button button=(Button) findViewById(R.id.but);
         button.setText("Hey!!");
         setContentView(R.layout.main);
         }
}

Thnx…

Answer 1

You have to use setContentView(R.layout.main); before using findViewById().

If you don’t do that, findViewById() will return null (since no view with that ID is in the current layout) and you will get a NullPointerException when trying to set the text on the TextView.

The correct version of onCreate() should look like this:

public void onCreate(Bundle i) {
    super.onCreate(i);

    setContentView(R.layout.main);
    Button button = (Button) findViewById(R.id.but);
    button.setText("Hey!!");
}