Java编程测试_类的使用

 package test;

 class A
 {
     private static int i;           // Static, Private Attribute
     private static int j;           // Static, Private Attribute
     private static int cnt = 0;        // Statistic the number of the object
     void set(int a , int b)         // Set the value by the function in class
     {                                   // The security can be guaranteed
         i = a;
         j = b;
     }

     public A(int a , int b)     // Construction Method
     {
         System.out.printf("The function has been called!\n");
         i = a;
         j = b;
         cnt++;
     }

     public static int Cnt()     //Get the number of the object in this class
     {                            //It should can be static because we can
         return cnt;                //A.Cnt
     }

     public void show()         // A Show Method in the class
     {
         System.out.printf("The value in this object: i=%d,j=%d\n",i,j);
     }

 }

 ///////////Extends/////////////////////
 class Human
 {
     public String name = "Mike";
     public int age = 22;
     }

 class Student extends Human
 {
     public double score = 90;
     }

 class Graduate extends Student
 {
     public String tutor = "Jay";
     }
 /*************Extends**********************/

 public class TestMemo {

     static int add(int a ,int b)                // The reentry of a function
     {
         return (a+b);
     }

     static int add(int a ,int b , int c)        // The reentry of a function
     {
         return (a+b+c);
     }

     static double add(double a ,double b)        // The reentry of a function
     {
         return a+b;
     }
     public static void main(String[] args)        // The reentry of a function
     {
         A aa = new A(66,88);
 //        aa.i = 100;
 //        aa.j = 20;
         //aa.set(50, 67);
         aa.show();
         System.out.printf("Two int value be plused:%d\n",add(2,8));
         System.out.printf("Three int value be plused:%d\n",add(1,2,3));
         System.out.printf("Two float value be plused:%f\n",add(1.9,2.0));
         A bb = new A(12,10);              //change the value in the class by another object
         aa.show();                        // because of the static attribute
         System.out.printf("The vaule count in A class: %d\n",A.Cnt());
         Graduate stu = new Graduate();
         System.out.printf("Test of EXTENDS: %s's tutor is %s\n",stu.name,stu.tutor);
         System.out.printf("Test of EXTENDS: %s's age is %d\n",stu.name,stu.age);
     }
 }