Question

I am trying to create array of buttons, then making one onClick event for all, here is my code, when I run the code I get (The application testing(processcom.MyTest.testing) has stopped unexpectedly. Please try again) I am not sure what, where is the error. I must be missing something fundamental, I am not trying to create app, I am just leanring Java, specially for Android.

Here is my code

package com.MyTest.testing;


import static android.widget.Toast.makeText;
import java.util.Random;
import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import android.view.View;
import android.view.View.OnClickListener;


public class TreActivity extends Activity {
      /** Called when the activity is first created. */
//declaring some public int vars

int isPressed1 = 1;
int isPressed2 = 1;
int isPressed3 = 1;
int isPressed4 = 1;
int isPressed5 = 1;
int isPressed6 = 1;
int isPressed7 = 1;
int isPressed8 = 1;
int isPressed9 = 1;
int isPressed10 = 1;





@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);


   myMethod();





}; //End of onCreate (Bundle savedInstanceState) 

public void myMethod() { 
    MyClickHandler handler = new MyClickHandler();  

    Button[] buttons = fnButtonArray();
    for (Button button : buttons) {  
       button.setOnClickListener(handler);  
       }  
 }  


class MyClickHandler implements View.OnClickListener {  
      public void onClick(View v) { 
        Toast.makeText(TreActivity.this, ((Button) v).getText() , Toast.LENGTH_SHORT).show();
      }  
 }


public Button[] fnButtonArray(){

    Button arrButtons[] = new Button[11];
      // started with 1 not 0 for the array to match the button numbers
    arrButtons[1] = (Button) findViewById(R.id.btn1);
    arrButtons[2] = (Button) findViewById(R.id.btn2);
    arrButtons[3] = (Button) findViewById(R.id.btn3);
    arrButtons[4] = (Button) findViewById(R.id.btn4);
    arrButtons[5] = (Button) findViewById(R.id.btn5);
    arrButtons[6] = (Button) findViewById(R.id.btn6);
    arrButtons[7] = (Button) findViewById(R.id.btn7);
    arrButtons[8] = (Button) findViewById(R.id.btn8);
    arrButtons[9] = (Button) findViewById(R.id.btn9);
    arrButtons[10]= (Button) findViewById(R.id.btn10);
    return arrButtons;

  }
  } //public class TreActivity extends Activity

Answer 1

It looks like you’re getting a NullReferenceException. You create an array of size 26 but only fill the 2nd through 11th elements. Then you loop through all 26 elements trying to assign a click handler. When you try to assign a click handler to a null element, an exception is thrown.

You’ll probably be able to see these details by checking LogCat. You can access LogCat in Eclipse or run adb logcat from the terminal.