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讲述java中enum的用法.docx

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讲述java中enum的用法 讲述java中enum的用法本文实例讲述了java中enum的用法。分享给大家供大家参考。具体分析如下：1.基本用法复制代码代码如下:enumDay{SUNDAY,MONDAY,TUESDAY,WENDSDAY,THURSDAY,FRIDAY,SATURDAY;}枚举是常量，所以应该用大写。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{publicstaticvoidmain(String[]args){for(Dayday:Day.values()){System.out.println(day);}}}3.枚举可以带字段和方法，以下示例来自官方TheJavaTutorials复制代码代码如下:publicenumEnumDemo{AOBJECT("fieldone","fieldtwo");privateStringfield1;privateStringfield2;EnumDemo(Stringval1,Stringval2){this.field1=val1;this.field2=val2;}publicvoidprintFields(){System.out.println(this.field1);System.out.println(this.field2);}publicstaticvoidmain(String[]args){EnumDemo.AOBJECT.printFields();}}以下现实中的示例来自官方的JavaTutorial:复制代码代码如下:publicenumPlanet{MERCURY(3.303e+23,2.4397e6),VENUS(4.869e+24,6.0518e6),EARTH(5.976e+24,6.37814e6),MARS(6.421e+23,3.3972e6),JUPITER(1.9e+27,7.1492e7),SATURN(5.688e+26,6.0268e7),URANUS(8.686e+25,2.5559e7),NEPTUNE(1.024e+26,2.4746e7);privatefinaldoublemass;//inkilogramsprivatefinaldoubleradius;//inmetersPlanet(doublemass,doubleradius){this.mass=mass;this.radius=radius;}privatedoublemass(){returnmass;}privatedoubleradius(){returnradius;}//universalgravitationalconstant(m3kg-1s-2)publicstaticfinaldoubleG=6.67300E-11;doublesurfaceGravity(){returnG*mass/(radius*radius);}doublesurfaceWeight(doubleotherMass){returnotherMass*surfaceGravity();}publicstaticvoidmain(String[]args){DoubleearthWeight=120;for(Planetp:Planet.values()){System.out.println(p.surfaceGravity());System.out.println(p.surfaceWeight(earthWeight/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{INSTANCE(newString[]{"arg1","arg2"});String[]myArgs;Singleton(String[]args){this.myArgs=args;}publicstaticSingletongetInstance(){returnINSTANCE;}publicstaticvoidmain(String[]args){for(Stringarg:INSTANCE.myArgs)System.out.println(arg);}}