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：

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......");    }}

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......