Java enumeration (enum) detailed 7 common usage

JDK1.5 introduces a new type--enumeration. In Java it is a "small" function, but to my development has brought "big" convenience.

Big Brother I add my own understanding, to help you understand. usage One: Constants

Before JDK1.5, we defined constants as: public static fianl ...  Now that you have enumerations, you can group related constants into an enumeration type, and enumerations provide more methods than constants. Java code public enum Color {RED, GREEN, BLANK, yellow}

usage two: switch

The switch statement before JDK1.6 only supports the Int,char,enum type, and using enumerations makes our code more readable.   Java code   enum signal {       green, yellow, red   }   public class trafficlight {       signal  color = Signal.RED;       public void change ()  {            switch  (color)  {            case RED:                color = Signal.GREEN;                break;           case  yellow:               color =  signal.red;               break;           case green :               color =  signal.yellow;               break;            }       }  }   

usage Three: Add a new method to the enumeration

If you intend to customize your own method, you must add a semicolon at the end of the sequence of enum instances. and  Java  requirements must first define the  enum  instance.   Java code   public enum color {       red ("Red",  1),  green ("green",  2),  blank ("white",  3),  yello ("Yellow",  4);        //  member variables        private String name;        private int index;       //  Construction Method         private color (string name, int index)  {            this.name = name;            this.index = index;       }        //  General method        public static string getname (int  index)  {      &NBsp;    for  (Color c : color.values ())  {                if  (C.getindex ()  == index)  {                     return c.name;               }            }            return null;       }       // get  set  methods        public string getname ()  {           return name;       }        public void setname (string name)  {            this.name = name;       }        public int getindex ()  {            return index;       }       public void  setindex (int index)  {           this.index  = index;       }  }  

usage Four: Methods of overriding enumerations

An example of a ToString () method overlay is given below.   Java code   public enum color {       red ("Red",  1),  green ("green",  2),  blank ("white",  3),  yello ("Yellow",  4);        //  member variables        private String name;        private int index;       //  Construction Method         private color (string name, int index)  {            this.name = name;            this.index = index;       }        //covering method         @Override        public  string tostring ()  {           return this.index+ "_" +this.name;       }  }  

Usage Five: Implement Interface

All enumerations inherit from the Java.lang.Enum class. Because Java does not support