Android : Android setX method doesn't work in some situations

I extend a Viewgroup and when I use setX in this constructor ,it works well.However it doesn't work when I put the setX method in onMeasure or onLayout methods. Why I need to put it into the latter 2 methods is because that I need to calculate how much I need for setX method.

Thanks for any help!

public class CustomProgressBar extends ViewGroup {
private Context context;
//....
public CustomProgressBar(Context context,AttributeSet attrs) {
    super(context,attrs);
    this.context=context;
    //setX(-200); works here
    }
   @Override 
   public void onMeasure(int measureSpecX,int measureSpecY){
    //...
    //    setX(-200); doesn't work here
    }


@Override
protected void onLayout(boolean arg0, int l, int t, int r, int b) {
//...   
}
  }