switch demo

package day03; import java.util.Scanner; public class Command { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.println("请选择功能: 1.显示全部记录 2.查询登录记录 0.退出"); int command = scan.nextInt(); switch(command){ case 1: System.out.println("显示全部记录"); break; case 2: System.out.println("查询登录记录"); break; case 0: System.out.println("欢迎使用"); break; default: System.out.println("输入错误"); } } } package day03; import java.util.Scanner; public class Command { public static void main(String[] args) { Scanner scan = new Scanner(System.in); System.out.println("请选择功能: 1.显示全部记录 2.查询登录记录 0.退出"); int command = scan.nextInt(); switch(command){ case 1: System.out.println("显示全部记录"); break; case 2: System.out.println("查询登录记录"); break; case 0: System.out.println("欢迎使用"); break; default: System.out.println("输入错误"); } } }

demo..java

对对象的引用指向的描述package oo.day02; public class Demo { public static void main(String[] args) { /* Cell c = new Cell(); Cell cc = c; //指向同一个对象 cc.row = 5; c.row = 8; System.out.println(cc.row); //8 int num = 8; int num2 = num; //赋值 num2 = 88; System.out.println(num); //8 */ /* Cell c = new Cell(); c.row = 2; System.out.println(c.row); c = null; //空，不再指向任何对象 System.out.println(c.row); //空指针异常(NullPointerException) */ }