Expand Collapse Animation of a view

ExpandCollapse.java

	public void collapse(final View v) {
		final int initialHeight = v.getMeasuredHeight();

		Animation a = new Animation() {
			@Override
			protected void applyTransformation(float interpolatedTime,
					Transformation t) {
				if (interpolatedTime == 1) {
					v.setVisibility(View.GONE);
				} else {
					v.getLayoutParams().height = initialHeight
							- (int) (initialHeight * interpolatedTime);
					v.requestLayout();
				}
			}

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

		// 1dp per milliseconds
		a.setDuration((int) (initialHeight / v.getContext().getResources()
				.getDisplayMetrics().density));
		v.startAnimation(a);
	}

	public void expand(final View v) {
		v.measure(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
		final int measuredHeight = v.getMeasuredHeight();

		v.getLayoutParams().height = 0;
		v.setVisibility(View.VISIBLE);
		Animation a = new Animation() {
			@Override
			protected void applyTransformation(float interpolatedTime,
					Transformation t) {
				v.getLayoutParams().height = interpolatedTime == 1 ? LayoutParams.WRAP_CONTENT
						: (int) (measuredHeight * interpolatedTime);
				v.requestLayout();
			}

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

		// 1dp per milliseconds
		a.setDuration((int) (measuredHeight / v.getContext().getResources()
				.getDisplayMetrics().density));
		v.startAnimation(a);
	}