This code is taken from a project I was working on some time back. I think it does what you need.
First of all, I have no idea about how you have created the lines for the star. I just used vector drawables to create the star lines (for more details about how to work with VectorDrawables have a look at this post). I should warn you that I made it in a hurry so it's not going to be pretty
Warning: This post is going to be long
star1.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="48dp"
android:height="48dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path android:pathData="M20,24L12,0"
android:strokeColor="@color/starColor"
android:strokeWidth="0.1"/>
</vector>
star2.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="48dp"
android:height="48dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path android:pathData="M4,24L12,0"
android:strokeColor="@color/starColor"
android:strokeWidth="0.1"/>
</vector>
star3.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="48dp"
android:height="48dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path android:pathData="M0,8L24,8"
android:strokeColor="@color/starColor"
android:strokeWidth="0.1"/>
</vector>
star4.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="48dp"
android:height="48dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path android:pathData="M4,24L24,8"
android:strokeColor="@color/starColor"
android:strokeWidth="0.1"/>
</vector>
star5.xml
<vector xmlns:android="http://schemas.android.com/apk/res/android"
android:width="48dp"
android:height="48dp"
android:viewportWidth="24.0"
android:viewportHeight="24.0">
<path android:pathData="M20,24L0,8"
android:strokeColor="@color/starColor"
android:strokeWidth="0.1"/>
</vector>
Ok. Now that you have all the required drawables, let's jump to the Activity XML and create the layout. Just the basic stuff here. I'll be using 5 ImageViews to hold the different star lines (which makes it convenient to animate but could cause performance issues which we'll talk about later on). I'll be using a ConstraintLayout as the root view.
activity_test.xml
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/image1"
android:layout_width="200dp"
android:layout_height="200dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:alpha="0"/>
<ImageView
android:id="@+id/image2"
android:layout_width="200dp"
android:layout_height="200dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:alpha="0"/>
<ImageView
android:id="@+id/image3"
android:layout_width="200dp"
android:layout_height="200dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:alpha="0"/>
<ImageView
android:id="@+id/image4"
android:layout_width="200dp"
android:layout_height="200dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:alpha="0"/>
<ImageView
android:id="@+id/image5"
android:layout_width="200dp"
android:layout_height="200dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:alpha="0"/>
</android.support.constraint.ConstraintLayout>
As you might have noticed I have not assigned any of the drawables to the ImageView using the android:src property. I'd encourage you to go ahead and try doing that. Meanwhile I am adding the images programmatically.
Above the onCreate method declare the following variables
private ImageView image1, image2, image3, image4, image5;
private Context context;
private int i = 1;
private long duration = 800;
private Handler animHandler;
animHandler is going to be responsible to keep the animation running. I'll be using i to keep track of which ImageView to animate. And as the name suggests, the field duration is going to hold the required duration for the animation.
Here is the rest of the code. I'll be providing comments wherever possible.
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
// Initialising the imageview. I'm using SDK 26 so I did not
// require typecasting.
image1 = findViewById(R.id.image1);
image2 = findViewById(R.id.image2);
image3 = findViewById(R.id.image3);
image4 = findViewById(R.id.image4);
image5 = findViewById(R.id.image5);
context = TestActivity.this;
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
setupView(); // This method will initialize all IVs
// and add the vector drawable as bitmap
animHandler = new Handler();
startAnim();
}
}, 200);
}
setupView
private void setupView() {
setVectorDrawable(image1, ContextCompat.getDrawable(context,R.drawable.star1));
setVectorDrawable(image2, ContextCompat.getDrawable(context,R.drawable.star2));
setVectorDrawable(image3, ContextCompat.getDrawable(context,R.drawable.star3));
setVectorDrawable(image4, ContextCompat.getDrawable(context,R.drawable.star4));
setVectorDrawable(image5, ContextCompat.getDrawable(context,R.drawable.star5));
}
setVectorDrawable
private void setVectorDrawable(ImageView imageView, Drawable drawable) {
Bitmap bitmap = Bitmap.createBitmap(imageView.getWidth(),
imageView.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
drawable.draw(canvas);
imageView.setImageBitmap(bitmap);
}
Over here, I'm creating 5 different bitmaps to hold the 5 lines. This won't be too much of an issue just yet. But for bigger projects (I had to use 69 bitmaps together) having a lot of bitmaps in the memory is probably not a good practice. 5 bitmaps should work just fine.
startAnim
private void startAnim() {
runnable.run();
}
runnable
Runnable runnable = new Runnable() {
@Override
public void run() {
switch (i) {
case 1:
animateStarIn(image1);
break;
case 2:
animateStarIn(image2);
break;
case 3:
animateStarIn(image3);
break;
case 4:
animateStarIn(image4);
break;
case 5:
animateStarIn(image5);
break;
case 6:
animateStartOut(image1);
break;
case 7:
animateStartOut(image2);
break;
case 8:
animateStartOut(image3);
break;
case 9:
animateStartOut(image4);
break;
case 10:
animateStartOut(image5);
break;
}
i++;
if (i == 11) i = 1;
animHandler.postDelayed(runnable, duration);
}
};
private void animateStarIn(ImageView imageView) {
imageView.animate().alpha(1).setDuration(duration).setInterpolator(new AccelerateInterpolator());
}
private void animateStartOut (ImageView imageView) {
imageView.animate().alpha(0).setDuration(duration).setInterpolator(new DecelerateInterpolator());
}
To be brief, I am creating a runnable that will animate the different ImageViews differently depending on the value variable i holds.
Let me stress again that I have posted this code from a project that I worked on some time back. Even if it does not meet your requirement directly I'd encourage you to experiment and play around with it for a bit to get it working.
Edit
This animation works by ensuring the runnable repeats. To stop the animation use
animHandler.removeCallbacks(runnable);
