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);
    }
}