animation - Animate change width of android RelativeLayout -

i need change width of relativelayout 0 600px programmatically, in animated way. i'm using following code:

animation = new animation() {     @override     protected void applytransformation(float interpolatedtime, transformation t) {         relativelayout.layoutparams drawerparams = (layoutparams) drawer.getlayoutparams();         drawerparams.width = 600;         drawer.setlayoutparams(drawerparams);     } };  a.setduration(1000); //animate 1s layout.startanimation(a); 

however, reason isn't working. can point me in right direction?

i typed , works perfect here

animation

public class resizewidthanimation extends animation {     private int mwidth;     private int mstartwidth;     private view mview;      public resizewidthanimation(view view, int width)     {         mview = view;         mwidth = width;         mstartwidth = view.getwidth();     }      @override     protected void applytransformation(float interpolatedtime, transformation t)     {         int newwidth = mstartwidth + (int) ((mwidth - mstartwidth) * interpolatedtime);          mview.getlayoutparams().width = newwidth;         mview.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;     } } 

usage

if(animate) {     resizewidthanimation anim = new resizewidthanimation(leftframe, leftfragmentwidthpx);     anim.setduration(500);     leftframe.startanimation(anim); } else {     this.leftfragmentwidthpx = leftfragmentwidthpx;     layoutparams lp = (layoutparams) leftframe.getlayoutparams();     lp.width = leftfragmentwidthpx;     leftframe.setlayoutparams(lp); }