public void invalidateLayout(Container parent){
  checkParent(parent);
synchronized (parent.getTreeLock()) {
    isValid=false;
  }
}

public void invalidateLayout ( Container parent ) { checkParent ( parent ) ; synchronized ( parent . getTreeLock ( ) ) { isValid = false ; } }
invalidates the layout , indicating that if the layout manager has cached information it should be discarded .
