1.算数运算符

1.1核心代码

System.out.println("请输入一个4位数：");
        Scanner scanner1 = new Scanner(System.in);
        int Input1  = scanner1.nextInt();
        int singlenumber1 = Input1%10;
        int tennumber1 =  (Input1/10)%10;
        int hundrednumber1 = (Input1/100)%10;
        int kilobit1 = (Input1/1000)%10;
        System.out.println("再输入一个4位数：");
        Scanner scanner2 = new Scanner(System.in);
        int Input2  = scanner2.nextInt();
        int singlenumber2 = Input2%10;
        int tennumber2 =  (Input2/10)%10;
        int hundrednumber2 = (Input2/100)%10;
        int kilobit2 = (Input2/1000)%10;
        System.out.println("结果是：" + (singlenumber1+singlenumber2+tennumber1+tennumber2+hundrednumber1+hundrednumber2+kilobit1+kilobit2));

1.2运行结果

ZY1.png

2.拼接运算符

2.1核心代码

Scanner scanner = new Scanner(System.in);
        System.out.println("请输入名字：");
        String name = scanner.next();

        System.out.println("请输入年龄：");
        String age = scanner.next();

        System.out.println("请输入性别：");
        String gender = scanner.next();

        System.out.println("请输入地址：");
        String address = scanner.next();

        System.out.println("请输入邮箱：");
        String email = scanner.next();

        System.out.print("我的名字是"+ name +"，今年" + age + "岁，性别是" + gender + "，住在" + address + "，我的联系方式是：" + email);

2.2运行结果

ZY2.png

3.自增自减过程分析

3.1代码分析

      //定义a,b,c
        int a,b,c;
     //4赋值给a，5赋值给b，c赋值6；
        a = 4;b = 5;c = 6;
   //a++ 先运算后自增, (a++)==b 中a使用之前的值为4，b值为5，4不等于5，所以x为 false ；（这之后a=5，b=5,c=6)
        boolean x = ((a++)==b);
     //b++ 先运算后自增,而 --c 先自减后运算， (b++)==(--c) 中b使用之前的值为5，c使用自减后的值为5，5等于5，所以y为 true ；（这之后a=5，b=6,c=5)
        boolean y = ((b++)==(--c));
//a=5，b=6，不相等，输出false
        System.out.println(a==b);
//!x为 true ,y也为 true ,以 !x&y 为 true ,输出 true
        System.out.println((!x&y));

4.switch实现用户登录

4.1核心代码

Scanner scanner = new Scanner(System.in);
        System.out.println("请输入用户名");
        String username = scanner.next();
        System.out.println("请输入密码");
        int password = scanner.nextInt();
        switch (username){
            case "jack":
                if (password == 123){
                    System.out.println("恭喜"+ username+"登录成功");
                }else{
                    System.out.println("用户名正确，密码错误");
                }break;
            case "rose":
                if (password == 456){
                    System.out.println("恭喜"+ username+"登录成功");
                }else {
                    System.out.println("用户名正确，密码错误");
                }break;
            case "admin":
                if (password == 789){
                    System.out.println("恭喜"+ username+"登录成功");
                } else {
                    System.out.println("用户名正确，密码错误");
                }break;
            default:
                System.out.println("用户输入错误");
        }

4.2运行结果

4.2.1 用户1登录成功

jack.png

4.2.2 用户2登录成功

rose.png

4.2.3 用户3登录成功

admin.png

4.2.4 用户名正确，密码错误

cuo1.png

4.2.5 输入错误

cuo2.png