How to draw to canvas on onResume

Question

I have an android app that draws to a canvas. Up to now I've been drawing each time I create the app usine onCreate as such:

package com.example.drawdemo;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;

public class DrawDemo extends Activity {
    DrawView drawView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        drawView = new DrawView(this);
        drawView.setBackgroundColor(Color.WHITE);
        setContentView(drawView);
    }
}

However I'd like to migrate the drawing to onResume. Ideally I do not draw the first time someone starts the program, only when they resume the program. Why do the following two code snippets not work:?

package com.example.drawdemo;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;

public class DrawDemo extends Activity {
    DrawView drawView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        drawView = new DrawView(this);
        drawView.setBackgroundColor(Color.WHITE);
        setContentView(drawView);
    }

    @Override
    public void onResume(){
        drawView = new DrawView(this);
        drawView.setBackgroundColor(Color.WHITE);
        setContentView(drawView);
    }
}

and

package com.example.drawdemo;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;

public class DrawDemo extends Activity {
    DrawView drawView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

    }

    @Override
    public void onResume(){
        drawView = new DrawView(this);
        drawView.setBackgroundColor(Color.WHITE);
        setContentView(drawView);
    }
}

Answer 1

Make sure you call super.onResume() - your activity will not function properly without it.