How to expand a layout height with animation?

Two simple ways to do this without an Animation class:

1) Set android:animateLayoutChanges="true" in you xml layout file

2) Use a ViewProperty animator

layout.setPivot(0);
layout.animate().scaleY(scaleFactor).setDuration(500);

The pivot tells the view where to scale from, default is in the middle, which in my experience is almost never what you want. The duration is optional (default = 1000).

Please check below new edited answer as below. But here you need to know the exact new height.

public class LayoutAnimationActivity extends Activity {
    RelativeLayout ril1;
    Button btn;
    int initialHeight;
    int actualHeight;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main2);
        ril1 = (RelativeLayout) findViewById(R.id.relativeLayout1);
        btn = new Button(this);
        btn.setWidth(100);
        btn.setHeight(200);
        btn.setText("Button");
        actualHeight = 210;
        Ani a = new Ani();
        a.setDuration(2000);
        ril1.startAnimation(a);
    }

    class Ani extends Animation {
        public Ani() {}

        @Override
        protected void applyTransformation(float interpolatedTime, Transformation t) {
            int newHeight;

            newHeight = (int) (initialHeight * interpolatedTime);

            ril1.removeAllViews();
            btn.setWidth(100);
            btn.setHeight(300);
            btn.setText("as");
            ril1.addView(btn);             
            ril1.getLayoutParams().height = newHeight;
            ril1.requestLayout();
        }

        @Override
        public void initialize(int width, int height, int parentWidth, int parentHeight) {
            super.initialize(width, height, parentWidth, parentHeight);
            initialHeight = actualHeight;
        }

        @Override
        public boolean willChangeBounds() {
            return true;
        }
    };
}

You marked the solution that was closest. This is the exact solution. I had the same problem. Hopefully this answer will help others.

InstantiateResizeAnimation

ResizeAnimation resizeAnimation = new ResizeAnimation(
     view, 
     targetHeight, 
     startHeight
); 
resizeAnimation.setDuration(duration); 
view.startAnimation(resizeAnimation);

ResizeAnimation class should look like this

public class ResizeAnimation extends Animation {
    final int targetHeight;
    View view;
    int startHeight;

    public ResizeAnimation(View view, int targetHeight, int startHeight) {
        this.view = view;
        this.targetHeight = targetHeight;
        this.startHeight = startHeight;
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        int newHeight = (int) (startHeight + targetHeight * interpolatedTime);
        //to support decent animation, change new heigt as Nico S. recommended in comments
        //int newHeight = (int) (startHeight+(targetHeight - startHeight) * interpolatedTime);
        view.getLayoutParams().height = newHeight;
        view.requestLayout();
    }

    @Override
    public void initialize(int width, int height, int parentWidth, int parentHeight) {
        super.initialize(width, height, parentWidth, parentHeight);
    }

    @Override
    public boolean willChangeBounds() {
        return true;
    }
}

You need a scale animation here is the official documentation

this is in code

private void animate() {
    ImageView imageView = (ImageView) findViewById(R.id.ImageView01);
    ScaleAnimation scale = new ScaleAnimation((float)1.0, (float)1.5, (float)1.0, (float)1.5);
    scale.setFillAfter(true);
    scale.setDuration(500);
    imageView.startAnimation(scale); 
}