public void changeTickFontSize(int delta){
  Font f=getTickLabelFont();
  String fName=f.getFontName();
  Font newFont=new Font(fName,f.getStyle(),(f.getSize() + delta));
  setTickLabelFont(newFont);
}

public void changeTickFontSize ( int delta ) { Font f = getTickLabelFont ( ) ; String fName = f . getFontName ( ) ; Font newFont = new Font ( fName , f . getStyle ( ) , ( f . getSize ( ) + delta ) ) ; setTickLabelFont ( newFont ) ; }
increases or decreases the tick font size .
