android - Why is Thread.sleep not working -

i new android , java , having trouble using thread.sleep function.my program simple game that's table tennis 2 players. code not complete thread not working properly.i changing margins move ball.is catch block being run because of exception > code follows :

package com.example.game; import android.app.activity; import android.app.activity; import android.content.context; import android.graphics.point; import android.os.bundle; import android.view.display; import android.view.menu; import android.view.menuitem; import android.view.view; import android.widget.button; import android.widget.imagebutton; import android.widget.imageview; import android.widget.linearlayout; import android.widget.relativelayout; import android.widget.toast;  public class mainactivity extends activity { private int x1=0,x2=0,m=150; public int height;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);       display display = getwindowmanager().getdefaultdisplay();       point size= new point();       display.getsize(size); //        int width = size.x;       height = size.y;       showview2();       showview1();       game(); } public void game() {     buttonsetup1_rig();     buttonsetup1_lef();     buttonsetup2_rig();     buttonsetup2_lef();  //while(m>=0)     for(int i=0;i<150;i++)     {         showball();         new thread(new runnable() {             @override             public void run() {                 try {                      thread.sleep(500);                     m=m-10;                   } catch (interruptedexception e) {                     e.printstacktrace();                 }              }         }).start();     }    }      protected void buttonsetup1_rig()     {       imagebutton ticon=(imagebutton)findviewbyid(r.id.imagebutton2);       ticon.setonclicklistener(new view.onclicklistener() {           public void onclick(view v) {             // todo auto-generated method stub               if(x1<(height-320))               x1=x1+10;               showview1();         } });     }     protected void buttonsetup1_lef()     {       imagebutton ticon=(imagebutton)findviewbyid(r.id.imagebutton1);       ticon.setonclicklistener(new view.onclicklistener() {           public void onclick(view v) {             // todo auto-generated method stub               if(x1>(0))               x1=x1-10;               showview1();         } });     }     protected void buttonsetup2_rig()     {       imagebutton ticon=(imagebutton)findviewbyid(r.id.imagebutton6);       ticon.setonclicklistener(new view.onclicklistener() {           public void onclick(view v) {             // todo auto-generated method stub               if(x2<(height-320))               x2=x2+10;               showview2();         } });     }     protected void buttonsetup2_lef()     {       imagebutton ticon=(imagebutton)findviewbyid(r.id.imagebutton4);       ticon.setonclicklistener(new view.onclicklistener() {           public void onclick(view v) {             // todo auto-generated method stub               if(x2>(0))               x2=x2-10;               showview2();         } });     }     public void showview1()      {           imageview image=(imageview)findviewbyid(r.id.imageview1);           linearlayout.layoutparams lp ;           lp=(linearlayout.layoutparams)(image.getlayoutparams());           lp.setmargins(x1,0,0,0);           image.setlayoutparams(lp);      }    public void showview2()      {           imageview image=(imageview)findviewbyid(r.id.imageview2);           linearlayout.layoutparams lp ;           lp=(linearlayout.layoutparams)(image.getlayoutparams());           lp.setmargins(x2,0,0,0);           image.setlayoutparams(lp);      }    public void showball()     {         imageview img=(imageview)findviewbyid(r.id.imageview3);         linearlayout.layoutparams l ;         l=(linearlayout.layoutparams)(img.getlayoutparams());         int leftmargin = l.leftmargin;         int rightmargin = l.rightmargin;         int topmargin = l.topmargin;         l.setmargins(m,0,m,0);         img.setlayoutparams(l);     } 

}

my xml :

<relativelayout     android:layout_width="match_parent"     android:layout_height="400dp" >      <relativelayout         android:id="@+id/relativelayout1"         android:layout_width="wrap_content"         android:layout_height="60dp"         android:layout_above="@+id/relativelayout2"         android:layout_alignparentleft="true"         android:layout_alignparentright="true"         android:layout_alignparenttop="true" >          <imagebutton             android:id="@+id/imagebutton4"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_alignparentleft="true"             android:layout_centervertical="true"             android:src="@drawable/left" />          <imagebutton             android:id="@+id/imagebutton5"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_alignparentbottom="true"             android:layout_alignparenttop="true"             android:layout_centerhorizontal="true"             android:src="@drawable/ic_launcher" />          <imagebutton             android:id="@+id/imagebutton6"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_alignparentright="true"             android:layout_centervertical="true"             android:src="@drawable/right" />     </relativelayout>      <relativelayout         android:layout_width="fill_parent"         android:layout_height="350dp"         android:layout_alignparentbottom="true"         android:layout_alignparentleft="true"         android:layout_below="@+id/relativelayout1" >          <linearlayout             android:id="@+id/linearlayout1"             android:layout_width="wrap_content"             android:layout_height="30dp"             android:layout_alignparentleft="true"             android:layout_alignparentright="true"             android:layout_alignparenttop="true"             android:orientation="vertical" >              <imageview                 android:id="@+id/imageview2"                 android:layout_width="wrap_content"                 android:layout_height="wrap_content"                 android:src="@drawable/lc" />         </linearlayout>          <linearlayout             android:id="@+id/linearlayout2"             android:layout_width="wrap_content"             android:layout_height="280dp"             android:layout_alignparentleft="true"             android:layout_alignparentright="true"             android:layout_below="@+id/linearlayout1"             android:orientation="vertical" >              <imageview                 android:id="@+id/imageview3"                 android:layout_width="wrap_content"                 android:layout_height="wrap_content"                 android:layout_marginleft="120dp"                 android:layout_margintop="140dp"                 android:src="@drawable/untitled" />          </linearlayout>          <linearlayout             android:layout_width="wrap_content"             android:layout_height="30dp"             android:layout_alignparentbottom="true"             android:layout_alignparentleft="true"             android:layout_alignparentright="true"             android:layout_below="@+id/linearlayout2"             android:orientation="vertical" >              <imageview                 android:id="@+id/imageview1"                 android:layout_width="wrap_content"                 android:layout_height="wrap_content"                 android:layout_marginleft="64dp"                 android:src="@drawable/lc" />          </linearlayout>      </relativelayout>  </relativelayout>  <relativelayout     android:layout_width="match_parent"     android:layout_height="49dp"     android:layout_weight="2.25" >      <imagebutton         android:id="@+id/imagebutton1"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_alignparentleft="true"         android:layout_centervertical="true"         android:src="@drawable/left" />      <imagebutton         android:id="@+id/imagebutton2"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_alignbottom="@+id/imagebutton1"         android:layout_alignparentright="true"         android:src="@drawable/right" />      <imagebutton         android:id="@+id/imagebutton3"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_centerhorizontal="true"         android:layout_centervertical="true"         android:src="@drawable/ic_launcher" /> </relativelayout>