Anonymous Inner Classes

public static Comparator integerComparator() {
        return new Comparator() {
           
            public int compare(Object o1, Object o2) {
                int val1 = ((Integer)o1).intValue();
                int val2 = ((Integer)o2).intValue();
                return (val1
            }
        };
    }

这个叫Anonymous Inner Classes，为了简化程序写法。
在看一个例子
class CloseFrame extends Frame{
     Label label;
     CloseFrame(String title) {
     super(title);
     label = new Label("Close the frame.");
     this.addWindowListener(new WindowAdapter(){
         public void windowClosing(WindowEvent e){
             dispose();
             System.exit(1);
         }
     });
}

可以写为：
class CloseFrame extends Frame{
     Label label;
     CloseFrame(String title) {
     super(title);
     label = new Label("Close the frame.");
     this.addWindowListener(new CFListener())；
     class CFListener extends WindowAdapter {
     {
         public void windowClosing(WindowEvent e){
             dispose();
             System.exit(1);
         }
     }
}