class FatherClass{ 
  public int value; 
  public void f(){ 
    value=100; 
    System.out.println 
    ("FatherClass.value:"+value); 
  } 
} 
 
 
class ChildClass extends FatherClass{ 
  public int value; 
  public void f(){ 
    super.f(); 
    value=200; 
    System.out.println 
    ("ChildClass.value:"+value); 
    System.out.println(value); 
    System.out.println(super.value); 
  } 
} 
 
 
public class test1 { 
  public static void main(String[] args){ 
    ChildClass cc=new ChildClass(); 
    cc.f(); 
  } 
} 

FatherClass.value:100
ChildClass.value:200
200
100

class SuperClass{ 
  private int n; 
   
  SuperClass(){ 
    System.out.println("调用SuperClass()"); 
  } 
  SuperClass(int n){ 
      System.out.println("调用SuperClass("+n+")"); 
    } 
} 
 
class SubClass extends SuperClass{ 
  private int n; 
   
  SubClass(int n){ 
     
    //当子类的构造方法中没有写super的时候，系统默认的调用父类的没有参数的构造方法 
    //相当于此处写了如下: 
    //super(); 
     
    System.out.println("调用SuberClass("+n+")"); 
    this.n=n; 
  } 
   
  SubClass(){ 
    super(300); 
    //在子类构造过程当中必须调用父类构造方法,并且super必须写在第一句（先有爸爸再有儿子） 
     
    System.out.println("调用SubClass()"); 
  } 
} 
public class test2 { 
  public static void main(String[] args){ 
    SubClass sc1=new SubClass(); 
     
    SubClass sc2=new SubClass(400); 
     
  } 
} 

调用SuperClass(300)
调用SubClass()
调用SuperClass()
调用SuberClass(400)