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Enum

2024-08-12 12:36:12   235人阅读

1.垃圾数据冗余,我们要求输错了就要给提示,而不是默认!

class Person{    private String name;    private String sex;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getSex() {        return sex;    }    public void setSex(String sex) {        if ("man".equalsIgnoreCase(sex) || "woman".equalsIgnoreCase(sex)) {            this.sex = sex;        }else{            this.sex = "man";        }    }    }public class EnumTest {    public static void main(String[] args) {        Person p = new Person();        p.setName("张三");        p.setSex("人妖");        System.out.println(p.getName()+"的性别是:"+p.getSex());//张三的性别是:man    }    }

 2.优化 抛出异常,但是是运行时异常,我们想要的是在编译的时候就给我们提示,所以还是要继续优化...

	public void setSex(String sex) {		if ("man".equalsIgnoreCase(sex) || "woman".equalsIgnoreCase(sex)) {			this.sex = sex;		}else{			throw new RuntimeException("性别不能乱输呀");		}	}

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3.继续优化: Enum的雏形到来了

class Person{	private String name;	private Gender sex;	public String getName() {		return name;	}	public void setName(String name) {		this.name = name;	}	public Gender getSex() {		return sex;	}	public void setSex(Gender sex) {//接收Gender类型		this.sex = sex ;	}}class Gender{//Enum的爷爷	String gender ;	private Gender(String gender){this.gender = gender;}//构造器私有化,防止别人new 对象,随意改变数据!	public static final Gender MAN = new Gender("man");	public static final Gender WOMAN = new Gender("wowan");}public class EnumTest {	public static void main(String[] args) {		Person p = new Person();		p.setName("张三");		p.setSex(Gender.WOMAN);		System.out.println(p.getName()+"的性别是:"+p.getSex().gender);//张三的性别是:wowan	}	}

　　4.Enum到来了!春天来了...

enum Gender{	MAN("man"),WOWAN("woman"); //枚举值必须放置第一行	String gender;	private Gender(String gender){this.gender = gender;}}public class EnumTest {	public static void main(String[] args) {		Person p = new Person();		p.setName("张三");		p.setSex(Gender.MAN);		System.out.println(p.getName()+"的性别是:"+p.getSex().gender);//张三的性别是:man	}	}

　　5.enum注意事项:

 

Enum


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