static runnable in Activity

Question

I am modifying the following code in my activity:

new Handler().postDelayed(new Runnable() {
 public void run() {
    txtStatus.setText("hello");
  }
}, 1000);

to:

static Runnable myRunnable = new Runnable() {
public void run() {
   txtStatus.setText("hello");
};

new Handler().postDelayed(myRunnable, 1000);

Which obviously doesn't work, since we're referencing a non static variable.

This doesn't work either:

public void setText() {
  txtStatus.setText("hello");
}
static Runnable myRunnable = new Runnable() {
public void run() {
   setText(); // doesn't work
   MyActivity.this.setText(); // still doesn't work

};

new Handler().postDelayed(myRunnable, 1000);

so how would my initial example be rewritten to use a static class instead of an anonymous inner class (to avoid the potential of a memory leak)?

Answer 1

Try something like this:

private Runnable myRunnable = new Runnable() {
    public void run() {
        txtStatus.setText("hello");
    }
};

// somewhere in code
txtStatus.postDelayed(myRunnable, 1000);

// in onPause or onDestroy
txtStatus.removeCallbacks(myRunnable);

Notes:

• this avoids memory leaks, as your run will never be called after onDestroy if you call removeCallbacks
• I replaced new Handler() with txtStatus, because every View has its own instance of Handler and there is no need to create additional one

Answer 2

You can use WeakReference to avoid memory leak problems. Here is some code, which illustrate this idea

public static class MyRunnable implements Runnable {

    private WeakReference<Activity> activityRef;

    public MyRunnable(Activity activity) {
        activityRef = new WeakReference<Activity>(activity);
    }

    public void run() {
         //some code
    }
}

private MyRunnable runnable = new MyRunnable(this);