Question

My second book for Android programming Hello, Android by Ed Burnette. I’m using eclipse. The code matches the book and it matches the code downloaded from the website of the book. But I know I’m doing something wrong here. I added a bunch of breakpoints where I figure (mostly guessing) where the problem might be happening. What I’ve come to is that this line of code is the culprit (SudokuActivity.java line 21) You can download the entire code here
http://kbsoftware.dlinkddns.com/Sudoku.zip

aboutButton.setOnClickListener(this);

but I just can’t figure out why ? It must be the result of something I’m doing wrong somewhere else. I’ve deleted and recreated the avd and that made no difference so not it. I’m at a lost here.

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

    View aboutButton = findViewById(R.id.about_button);
    aboutButton.setOnClickListener(this);
}    

I want to thank everyone who responded, it’s all fixed and working and I could not have done it without your help. I’ve learned more working on this problem then I would of in weeks if not months of problem free programming.

Answer 1

I downloaded your code and it runs correctly on my phone. So if your code is the same it should run.
It seems that findViewById didn’t find the view and then calling a method on a null object caused the nullpointerexception.

My dumb question: have you tried a project clean up? You can even try saving your classes, deleting the project and creating a new one.
Hope it helps