enum

1. What It Is

Used to define enumeration values. It is syntactic sugar implemented underneath through the Enum class.

2. How to Use It

enum Color
{RED, BLUE, GREEN}



class Test
{
    public static void main(String[] args)
    {
        System.out.println(Color.RED.name());//RED
        System.out.println(Color.RED.ordinal());//0
        System.out.println(Color.RED);//RED
        for (Color value : Color.values())
        {
            System.out.println(value);
        }
        System.out.println(Color.valueOf(Color.RED.name()));//RED

    }
}

3. Source Analysis

3.1. Enum

// An abstract class cannot be instantiated.
public abstract class Enum<E extends Enum<E>>
        implements Comparable<E>, Serializable {// Serializable and comparable
        // The name of the enum constant; accessible through name()
        private final String name;
        // The order of the enum constant, starting from 0; accessible through ordinal()
        private final int ordinal;

}