讲述java中enum的用法

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本文实例陈述了java中enum的用法。共享给大家供大家参考。概括分析如下：

1.根本用法

复制代码代码如下:enumDay

SUNDAY,MONDAY,TUESDAY,WENDSDAY,THURSDAY,FRIDAY,SATURDAY;

枚举是常量，所以理应用大写。

2.枚举是对象

枚举隐含地继承了java.lang.Enum，所以它具有java.lang.Enum的.属性和方法。遍历枚举：

复制代码代码如下:publicclassMain

publicstaticvoidmainString[]args

forDayday:Day.values

System.out.printlnday;

3.枚举可以带字段和方法，以下例如来自官方TheJavaTutorials

复制代码代码如下:publicenumEnumDemo

AOBJECTfieldone,fieldtwo;

privateStringfield1;

privateStringfield2;

EnumDemoStringval1,Stringval2

this.field1=val1;

this.field2=val2;

publicvoidprintFields

System.out.printlnthis.field1;

System.out.printlnthis.field2;

publicstaticvoidmainString[]args

EnumDemo.AOBJECT.printFields;

以下现实中的例如来自官方的JavaTutorial:

复制代码代码如下:publicenumPlanet

MERCURY3.303e+23,2.4397e6,

VENUS4.869e+24,6.0518e6,

EARTH5.976e+24,6.37814e6,

MARS6.421e+23,3.3972e6,

JUPITER1.9e+27,7.1492e7,

SATURN5.688e+26,6.0268e7,

URANUS8.686e+25,2.5559e7,

NEPTUNE1.024e+26,2.4746e7;

privatefinaldoublemass;//inkilograms

privatefinaldoubleradius;//inmeters

Planetdoublemass,doubleradius

this.mass=mass;

this.radius=radius;

privatedoublemassreturnmass;

privatedoubleradiusreturnradius;

//universalgravitationalconstantm3kg-1s-2

publicstaticfinaldoubleG=6.67300E-11;

doublesurfaceGravity

returnG*mass/radius*radius;

doublesurfaceWeightdoubleotherMass

returnotherMass*surfaceGravity;

publicstaticvoidmainString[]args

DoubleearthWeight=120;

forPlanetp:Planet.values

System.out.printlnp.surfaceGravity;

System.out.printlnp.surfaceWeightearthWeight/EARTH.surfaceGravity;

4.枚举是singleton，可以用枚举来构建一个Singleton

复制代码代码如下:publicenumSingleton

INSTANCEnewString[]arg1,arg2;

String[]myArgs;

SingletonString[]args

this.myArgs=args;

publicstaticSingletongetInstance

returnINST