public class ThisDemo {    
public ThisDemo()
    {        
    this.number=20;    
    }    
    public ThisDemo(int number,int number2)
    {        
    this();//调用无参数的构造函数        
    this.number2=number2;    
    }
    ThisDemo increment(){
        number++;        
        number2++;        
        return this;    
        }    
        private void print(){
        System.out.println("number="+number+";number="+number2);    
        }    
        public static void main(String[] args) {
        ThisDemo tt=new ThisDemo();        
        tt.increment().increment().increment().print();    
        }
}