对话框按钮单击时，Android应用程序崩溃

Question

Im trying to make a Dialog close when button is pressed.But Every time i press the button the application crashes.

public class CanvasPaint extends Activity implements OnClickListener {
    final Button widthbtn = (Button) findViewById(R.id.widthbtn);
    final  Button widthpopBtn = (Button) findViewById(R.id.widthpopBtn);

    final Context context = this;

    final Dialog widthDialog = new Dialog(context);

    widthbtn.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {

                widthpopBtn.setOnClickListener(new View.OnClickListener() {

                    @Override
                    public void onClick(View v) {
                        widthDialog.dismiss();
                    }
                });
                widthDialog.show();
        }
    });
}

Answer 1

That's some inception code. Why are you setting a click listener inside a click listener? It should be more like

widthbtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
            widthDialog.show();
    }
});

widthpopBtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
            widthDialog.dismiss();
    }
});

Answer 2

Your dialog layout is not properly inflated, and therefore, your widthpopBtn will be null. Try inflating the layout like this:

LayoutInflater inflater = getLayoutInflater();
View dialogView = inflater.inflate(R.layout.your_dialog_layout, null);
Button widthpopBtn = (Button) dialogView.findViewById(R.id.widthpopBtn);