public void blockContactAsync(String address) throws ImException {
  checkState();
  if (isBlocked(address)) {
    return;
  }
  if (mBlockPending.contains(address)) {
    return;
  }
  doBlockContactAsync(address,true);
}

public void blockContactAsync ( String address ) throws ImException { checkState ( ) ; if ( isBlocked ( address ) ) { return ; } if ( mBlockPending . contains ( address ) ) { return ; } doBlockContactAsync ( address , true ) ; }
blocks a certain contact . the contact will be removed from any contactlist after be blocked . if the contact has already been blocked , the method does nothing .
