设计模式——原型模式

一、任务

使用单例模式完成单一学号问题

二、类图

三、代码

1、Java

package tutorial7;

public class Client {
    public static void main(String a[])
    {
        IdnumberStudent no1,no2;
       no1=IdnumberStudent.getInstance();
       no2=IdnumberStudent.getInstance();
       System.out.println("学生学号号码是否一致：" + (no1==no2));
       
       String str1,str2;
       str1=no1.getIdnumberStudent();
       str2=no1.getIdnumberStudent();
       System.out.println("第一次号码：" + str1);
       System.out.println("第二次号码：" + str2);
       System.out.println("***************************");
       System.out.println("内容是否相等：" + str1.equalsIgnoreCase(str2));
       System.out.println("是否是相同对象：" + (str1==str2));
    }
}

package tutorial7;

public class IdnumberStudent {
    private static IdnumberStudent instance=null;
    private String no;
    
    private IdnumberStudent()
    {    
    }
    
    public static IdnumberStudent getInstance()
    {
        if(instance==null)
        {
            System.out.println("新生入学，分配学生学号！");
            System.out.println("***************************");
            instance=new IdnumberStudent();
            instance.setIdnumberStudent("20195589");        
        }
        else
        {
            System.out.println("重复分配学号，获取旧号码！");  
            System.out.println("***************************");
        }
        return instance;
    }
    
    private void setIdnumberStudent(String no)
    {
        this.no=no;
    }
    
    public String getIdnumberStudent()
    {
        return this.no;
    }
}

2、C++

#include<iostream>
#include<string>
using namespace std;

class IdnumberStudent
{
private:

    static IdnumberStudent* student;
    string no;
    IdnumberStudent() {};


    void setStudentNo(string no1)
    {
        no = no1;
    }

public:

    static IdnumberStudent* getStudent() {
        if (student == NULL) {
            cout << "新生入学，分配学生学号！" << endl;
            cout << "***************************" << endl;
            student = new IdnumberStudent();
            student->setStudentNo("20194023");
        }
        else {
            cout << "重复分配学号，获取旧号码！" << endl;
            cout << "***************************" << endl;
        }
        return student;
    }

    string getStudentNo() {
        return no;
    }

};

IdnumberStudent* IdnumberStudent::student = NULL;  //初始化 student

int main() {
    IdnumberStudent* no1, * no2;
    no1 = IdnumberStudent::getStudent();
    no2 = IdnumberStudent::getStudent();
    if (no1 == no2) {
        cout << "学生学号号码是否一致：true"<< endl;
    }
    else {
        cout << "学生学号号码是否一致：false" << endl;
    }
    string str1, str2;
    str1 = no1->getStudentNo();
    str2 = no2->getStudentNo();
    cout << "第一次号码：" + str1 << endl;;
    cout << "第二次号码：" + str2 << endl;
    cout << "***************************" << endl;
    if (str1 == str2) {
        cout << "内容是否相等：true" << endl;
    }
    else {
        cout << "内容是否相等：false" << endl;
    }
    if (str1 == str2) {
        cout << "是否是相同对象：true" << endl;
    }
    else {
        cout << "是否是相同对象：false" << endl;
    }
    
}

四、结果截图

1、Java结果截图

2、C++结果截图：