CODEWITHSUNDEEP
androidcanvas
user2789240
user2789240

Reputation: 97

Android Studio: Putting canvas and button using layout

I am reading a book on building an app called "Dot Smasher."

I decide to approach one of the task by adding a button above canvas. I decide to use LinearLayout and did the following:

public class MainActivity extends AppCompatActivity {

private Timer timer;
private DotSmasherCanvas canvas;
private DotSmasherTimerTask task;
private Button button;
private LinearLayout layout;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setTitle("DotSmasher");
    canvas = new DotSmasherCanvas(getBaseContext());
    timer = new Timer();
    task = new DotSmasherTimerTask(canvas);
    timer.schedule(task, 0, 1500);

    button = (Button) findViewById (R.id.button);

    layout = (LinearLayout) findViewById(R.id.layout);
    layout.addView(canvas);

    setContentView(R.layout.activity_main);



}
}

This is the xml file -- activity_main.xml:

enter image description here

I am able to get it work if I only did setContentView(canvas);

But not above, what did I do wrong?

There's no error display in Android Studio until I try to run it.

Upvotes: 0

Views: 513

Answers (1)

Gabe Sechan
Gabe Sechan

Reputation: 93614

You don't seem to understand how layouts work. You're calling findViewById before calling setContentView. That won't work- until you set a content view, there's no place to search for a view. And you shouldn't mix xml layouts and programmatic views unless you have a very dynamic layout- either your DotSmasherCanvas should be in the layout, or none of it should be in xml (probably the first).

Upvotes: 1

Related Questions