abtest.java

来自「这是java 2应用开发指南这本书上所有例子的源代码」· Java 代码 · 共 53 行

//ABTest.Java
//定义父类A
class A
{
        private int a;
        int i,j;
void setA(int a)
{
        this.a=a;
}
int getA()
{
        return a;
}
void setIJ(int i,int j)
{
        this.i=i;
        this.j=j;
}
}

class B extends A
{
        int k;
        void setK(int k)
        {
                this.k=k;
        }
        int sum()
{
        //return a+i+j+k;    错误，子类不能继承父类的私有变量a
        return i+j+k;
}
}
public class ABTest
{
        public static void main(String args[]){
          A father=new A();
          B child=new B();
          father.setA(5);
          father.setIJ(10,20);
          //System.out.println(“father.a＝“+father.a);    a为私有变量，不能直接访问
          System.out.println("father.a＝"+father.getA()); 
          System.out.println("father.i＝"+father.i);
          System.out.println("father.j＝"+father.j);
          child.setIJ(3,6);
          child.setK(12);
          System.out.println("child.i＝"+child.i); 
          System.out.println("child.j＝"+child.j); 
          System.out.println("child.k＝"+child.k);
          System.out.println("child.i+j+k＝"+child.sum());	
        }
}