Common uses of java-enumerations

usage One: Constants Public enumMycolor{red,black,blue} Public enumColor {RED, GREEN, BLANK, YELLOW} enum is a keyword for an enumeration class, using a method similar to a static constant: MyColor m=Mycolor.black; use two:SwitchenumSignal {GREEN, YELLOW, RED} Public classtrafficlight {Signal color=signal.red;  Public voidChange () {Switch(color) { CaseRed:color=Signal.green;  Break;  CaseYellow:color=signal.red;  Break;  CaseGreen:color=Signal.yellow;  Break; }    }} Public enumMycolor{red,black,blue} Public Static voidMain (string[] args) {MyColor m=Mycolor.black; Switch(m) { CaseRed:System.out.println ("MyColor is Red");  Break;  CaseBlack:System.out.println ("MyColor is Black");  Break; default: System.out.println ("MyColor is Blue");  Break; } System.out.println (M); NOTE: The switch statement supports Byte, Short，int，Charthe enumeration type. Usage Three: To add a new method custom method to the enumeration, you must add a semicolon at the end of the enum instance sequence. and Java requirements must first be definedenuminstance.  Public enumColor {RED ("Red", 1), Green ("green", 2), BLANK ("White", 3), Yello ("Yellow", 4); //member Variables PrivateString name;Private intindex;//Construction Method PrivateColor (String name,intindex) {   This. Name =name;  This. index =index;} //Common Methods  Public StaticString GetName (intindex) {   for(Color c:color.values ()) {if(C.getindex () = =index) {    returnC.name; }  }  return NULL; } //Get Set Method  PublicString GetName () {returnname;}  Public voidsetName (String name) { This. Name =name;}  Public intGetIndex () {returnindex;}  Public voidSetindex (intindex) {   This. index =index;}} Usage Four: Overrides the enumeration method below gives an example of the ToString () method overlay.  Public enumColor {RED ("Red", 1), Green ("green", 2), BLANK ("White", 3), Yello ("Yellow", 4); //member Variables PrivateString name;Private intindex;//Construction Method PrivateColor (String name,intindex) {   This. Name =name;  This. index =index;} //override Method@Override PublicString toString () {return  This. index+ "-" + This. Name;}}  Public enumColor {RED ("Red", 1), Green ("green", 2), BLANK ("White", 3), Yello ("Yellow", 4); //member Variables    PrivateString name; Private intindex; //Construction Method    PrivateColor (String name,intindex) {         This. Name =name;  This. index =index; }    //override Method@Override PublicString toString () {return  This. index+ "_" + This. Name; }} Use five: Implement an interface all enumerations inherit from the Java.lang.Enum class. Because Java does not support multiple inheritance, enumeration objects can no longer inherit from other classes.  Public InterfaceBehaviour {voidprint (); String getInfo ();} Public enumColorImplementsbehaviour{RED ("Red", 1), Green ("green", 2), BLANK ("White", 3), Yello ("Yellow", 4); //member Variables PrivateString name;Private intindex;//Construction Method PrivateColor (String name,intindex) {   This. Name =name;  This. index =index;}//interface Method@Override PublicString GetInfo () {return  This. Name; //interface Method@Override Public voidprint () {System.out.println ( This. index+ ":" + This. Name); }} Public InterfaceBehaviour {voidprint (); String getInfo ();} Public enumColorImplementsbehaviour{RED ("Red", 1), Green ("green", 2), BLANK ("White", 3), Yello ("Yellow", 4); //member Variables    PrivateString name; Private intindex; //Construction Method    PrivateColor (String name,intindex) {         This. Name =name;  This. index =index; }//interface Method@Override PublicString GetInfo () {return  This. Name; }    //interface Method@Override Public voidprint () {System.out.println ( This. index+ ":" + This. Name); }} Usage VI: Organizing enumerations using interfaces Public InterfaceFood {enumCoffeeImplementsfood{Black_coffee,decaf_coffee,latte,cappuccino}enumDessertImplementsfood{FRUIT, CAKE, GELATO}} Public InterfaceFood {enumCoffeeImplementsfood{Black_coffee,decaf_coffee,latte,cappuccino}enumDessertImplementsfood{FRUIT, CAKE, GELATO}} uses seven: The use of the enumeration collection, Java.util.EnumSet and Java.util.EnumMap, is a collection of two enumerations. Enumset guarantees that the elements in the collection are not duplicated; The key in Enummap is the enum type, and value can be any type. Refer to the JDK documentation for the use of this two collection. 

Common uses of java-enumerations