Question

I have those code:

public class ContentEditText extends EditText {
/*
 * Constructors
 */
public ContentEditText(Context context, AttributeSet attrs, int defStyle)
{
    super(context, attrs, defStyle);
}

public ContentEditText(Context context, AttributeSet attrs)
{
    super(context, attrs);
}

public ContentEditText(Context context)
{
    super(context);
}

/*
 * Listener
 */
@Override   
protected void onSelectionChanged(int selStart, int selEnd)
{ 
    Toast.makeText(getContext(), "selStart is " + selStart + "selEnd is " + selEnd, Toast.LENGTH_LONG).show();
}   
}

and

public class Main extends Activity {
private LinearLayout mainLayout;
private Button bBT;
private Button uBT;
private Button iBT;
private Button lBT;
private EditText titleET;
private ContentEditText contentET;
private Markup markup;

/** onCreate Function */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    initLayout();     
    setContentView(mainLayout);           
}

private void initLayout()
{
    // initialize some components by XML layout
    mainLayout = (LinearLayout) findViewById(R.id.main_layout);
    bBT = (Button) findViewById(R.id.boldBT);
    uBT = (Button) findViewById(R.id.underlineBT);
    iBT = (Button) findViewById(R.id.italicBT);
    lBT = (Button) findViewById(R.id.listBT);
    titleET = (EditText) findViewById(R.id.titleET);
    // initialize a EditText programmatically
    contentET = new ContentEditText(this);
    contentET.setGravity(Gravity.TOP);
    contentET.setLayoutParams(new LinearLayout.LayoutParams(
            LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
    // add the EditText to the main layout
    mainLayout.addView(contentET);
}

I thought I add contentET to the main layout by the right way, but it doesn’t work, the LogCat said “NullPointerException” for variable contentET, I don’t know why. Anyone can tell me where did i do wrong?
Thanks!

Answer 1

Chang your code to this as the first call should be setContentView after the super. Since this is not the case in your above code you are trying to access the layout without inflating it there fore it throwing nullpointer exception

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