在Android中实现用于搜索的动画

Question

Had been trying to implement a simple animation while one of my process is doing work in the background.

The requirement of animation is to create a ripple effect around a circular image view in the center of screen.

Examples can be seen in Google hangouts video session when there is some growing circle animation around profile circle or in apps like Tinder where it searches for profiles.

I have tried to put some 4 drawables of circles one over other and alter their visibility in a for loop:

ImageView one = (ImageView) rootView.findViewById(R.id.imageView1);
    ImageView two = (ImageView) rootView.findViewById(R.id.imageView2);
    ImageView three = (ImageView) rootView.findViewById(R.id.imageView3);
    ImageView four = (ImageView) rootView.findViewById(R.id.imageView4);

    try {
        for(int i=1; i<10; i++){
            one.setVisibility(one.VISIBLE);
            Thread.sleep(1000);

            two.setVisibility(two.VISIBLE);
            Thread.sleep(1000);

            three.setVisibility(three.VISIBLE);
            Thread.sleep(1000);

            four.setVisibility(four.VISIBLE);
            Thread.sleep(1000);

            one.setVisibility(one.INVISIBLE);
            Thread.sleep(1000);

            two.setVisibility(two.INVISIBLE);
            Thread.sleep(1000);

            three.setVisibility(three.INVISIBLE);
            Thread.sleep(1000);

            four.setVisibility(four.INVISIBLE);
            Thread.sleep(1000);

        }
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

But when I run this, the app is crashing. Is there a better way to do this?

Thanks in advance.

Answer 1

Is this being executed on a separate thread? If not, you should move it to one as Thread.sleep() should NEVER be used on the main thread.

With that said, you cannot execute UI related work (ie. setVisibility() ) off of the main UI thread. To use your current approach, you will need to add a runOnUiThread() around each of your setVisibility() calls.

If you would rather not do that, you can modify your code to the following:

ImageView one = (ImageView) rootView.findViewById(R.id.imageView1);
ImageView two = (ImageView) rootView.findViewById(R.id.imageView2);
ImageView three = (ImageView) rootView.findViewById(R.id.imageView3);
ImageView four = (ImageView) rootView.findViewById(R.id.imageView4);


final ImageView images[] = {one, two, three, four};
new Thread() {

    public void run() {

        for(int i=1; i<10; i++){
            for (int j=0; j<images.length; j++) {
                images[i].setAlpha(255);
                images[i].postInvalidate();
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            for (int j=0; j<images.length; j++) {
                images[i].setAlpha(0);
                images[i].postInvalidate();
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}.start();