Android Handler的规范使用

private static class MyHandler extends Handler {
    private final WeakReference<MainActivity> mReference;

    public MyHandler(MainActivity activity){
        mReference = new WeakReference<MainActivity>(activity);
    }
    @Override
    public void handleMessage(Message msg){
        super.handleMessage(msg);
        if (msg.what == 0) {
            MainActivity mainActivity = mReference.get();
            if (mainActivity != null) {
                mainActivity.doSomething(msg);
            }
        }
    }
}

在fragment中使用：

private static class MyHandler extends Handler {
    private final WeakReference<ThreeFragment> mReference;

    public MyHandler(ThreeFragment activity){
        mReference = new WeakReference<ThreeFragment>(activity);
    }

    @Override
    public void handleMessage(Message msg){
        super.handleMessage(msg);
        if (msg.what == REFRESH_ADAPTER) {
            ThreeFragment activity = mReference.get();
            if (activity != null) {
                activity.doSomething(msg);
            }
        }
    }
}