一、枚举类
1、定义枚举类
public enum EnumNum01 { SUCCESS, FAILED}新建一个类测试
public class TestEnum { public static void main(String[] args) { System.out.println(EnumNum01.SUCCESS); System.out.println(EnumNum01.FAILED); }}输出结果：
SUCCESSFAILED
2、定义枚举类，加入一个值
public enum EnumNum02 { A(1),B(2),C(3),D(4),E(5); private int num; EnumNum02(int num){ this.num=num; } public int getNum() { return num; } public void setNum(int num) { this.num = num; }}新建一个类测试：
public class EnumTest02 { public static void main(String args[]){ EnumNum02 b=EnumNum02.B; System.out.println(b.getNum()); }}运行结果：2
3、定义一个枚举类，加入两个值
public enum EnumNum01 { A(1,"1801"),B(2,"1802"),C(3,"1803"),D(4,"1804"); private int num; private String msg; EnumNum01(int num,String msg){ this.num=num; this.msg=msg; } public int getNum() { return num; } public void setNum(int num) { this.num = num; } public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; }}新建一个测试类：
public class EnumTest01 { public static void main(String args[]){ EnumNum01 a=EnumNum01.A; System.out.println(a); System.out.println(a.getNum()); System.out.println(a.getMsg()); }}运行结果：
A11801
二、单实例
1、IDEA默认创建的单例
public class Singleton01 { private static Singleton01 ourInstance = new Singleton01(); public static Singleton01 getInstance() { return ourInstance; } private Singleton01() { }}2、测试
（1）、新增加一个方法
public class Singleton01 { private static Singleton01 ourInstance = new Singleton01(); public static Singleton01 getInstance() { return ourInstance; } private Singleton01() { System.out.println("这是无参构造方法......"); } public void print(){ System.out.println("这是单例中增加的方法......"); }}
（2）、新建一个类测试
public class SingletonTest { public static void main(String args[]){ Singleton01 singleton01=Singleton01.getInstance(); singleton01.print(); }}运行结果：
这是无参构造方法......这是单例中增加的方法......
随时随地看视频
