Expand/Collapse animation

Animation.java

public static Animation expand(final View v, final boolean expand) { 
try { 
Method m = v.getClass().getDeclaredMethod("onMeasure", int.class, int.class); 
m.setAccessible(true); 
m.invoke( 
v, 
MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
MeasureSpec.makeMeasureSpec(((View)v.getParent()).getMeasuredWidth(), MeasureSpec.AT_MOST) 
); 
} catch (Exception e) { 
e.printStackTrace(); 
} 

final int initialHeight = v.getMeasuredHeight(); 

if (expand) { 
v.getLayoutParams().height = 0; 
} 
else { 
v.getLayoutParams().height = initialHeight; 
} 
v.setVisibility(View.VISIBLE); 

Animation a = new Animation() { 
@Override 
protected void applyTransformation(float interpolatedTime, Transformation t) { 
int newHeight = 0; 
if (expand) { 
newHeight = (int) (initialHeight * interpolatedTime); 
} else { 
newHeight = (int) (initialHeight * (1 - interpolatedTime)); 
} 
v.getLayoutParams().height = newHeight;	
v.requestLayout(); 

if (interpolatedTime == 1 && !expand) 
v.setVisibility(View.GONE); 
} 

@Override 
public boolean willChangeBounds() { 
return true; 
} 
}; 
a.setDuration(SPEED_ANIMATION_TRANSITION); 
return a; 
}