Java Enumeration Class enum introduction _java

Enum class Enum is introduced by JDK1.5, and is preceded by a public static final int Enum_value instead of an enumeration class. Enum class Enum is a special class that inherits the class Java.lang.Enum by default. As with other ordinary classes, an enum can also have member variables, methods, constructors, or one or more interfaces, the difference being:

1. If there is a constructor, it must be decorated with private.
2. An enumeration class cannot derive a child class.
3. Enumeration class All instances must display the definition in the first row. These instances are automatically added to the public static final modification by the system without the programmer displaying the definition.
4. Enumeration classes provide the values () method by default to facilitate traversal of all enumerated values

Methods in an enum (methods provided by the Enum):

Public final int compareTo (E o) compares enumerated values of the same type
The public final int ordinal () returns the indexed value of the enumeration, with the first enumeration value starting at zero.
Public final String name () returns the enumeration instance name
Public String toString () returns an enumerated output name

Traffic light Example

 public enum TrafficLight {red), yellow ("yellow"), Green ("green");
  private String name;
  Private TrafficLight (String name) {this.name = name;
  Public String GetName () {return name;
      public void Jude (TrafficLight light) {switch (light) {case RED:System.out.println ("Stop");
    Break
      Case YELLOW:System.out.println ("Go");
    Break
      Case GREEN:System.out.println ("Wait");
    Break
    Default:break; } public static void Main (string[] args) {for (TrafficLight e:trafficlight.values ()) {System.out.print
    ln (e.name ()); }
  }
}