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Java Enums

An enum is a special class that represents a group of constants like final variables. An enum is a special type of data type which is basically a collection/set of constants. Enum is short for enumerations which means specifically listed.

It can be used

Levels LOW, MEDIUM, HIGH.
Directions EAST, WEST, NORTH, SOUTH.
Thread States START, RUNNING, WAITING, DEAD.
Season SPRING, SUMMER, WINTER, AUTUMN, FALL.
Size SMALL, MEDIUM, LARGE, EXTRALARGE.
Suits Playing Cards CLUBS, DIAMONDS, HEARTS, SPADES.
Colors RED, YELLOW, BLUE, GREEN, WHITE, BLACK.
Purchage ORDERED, PICKING, PACKING, SHIPPING, READY, DELIVERED.
Operators ADDITION, SUBTRACTION, MULTIPLICATION, DIVISION, MODULUES.
Days SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY.
Planet MERCURY, VENUS, EARTH, MARS, JUPITER, SATURN, URANUS, NEPTUNE.
Months JANUARY, FEBRUARY, MARCH, APRIL, MAY, JUNE, JULY, AUGUST, SEPTEMBER, OCTOBER, NOVEMBER, DECEMBER.

Java Enums Examples (Outside Enums)

package com.jaladhi;
import java.util.Scanner;
public enum Days {
      SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
}
public class DaysTest {
      public static void main(String[] args) {
            Days days = Days.TUESDAY;
            switch(days) {
                  case SUNDAY:
                        System.out.println(days);
                        break;
                  case MONDAY:
                        System.out.println(days);
                        break;
                  case TUESDAY:
                        System.out.println(days);
                        break;
                  case WEDNESDAY:
                        System.out.println(days);
                        break;
                  case THURSDAY:
                        System.out.println(days);
                        break;
                  case FRIDAY:
                        System.out.println(days);
                        break;
                  case SATURDAY:
                        System.out.println(days);
                        break;
            }
      }
}

Output :

LOW
MEDIUM

package com.jaladhi;
import java.util.Scanner;
public enum Level {
      LOW, MEDIUM, HIGH
}

package com.jaladhi;
import java.util.Scanner;
public class LevelTest {
      public static void main(String[] args) {
            Level low = Level.LOW;
            System.out.println(low);
            Level medium = Level.MEDIUM;
            System.out.println(medium);
      }
}

Output :

TUESDAY

package com.jaladhi;
import java.util.Scanner;
public enum Thread {
      START, RUNNING, WAITING, DEAD;
}

package com.jaladhi;
import java.util.Scanner;
public class ThreadTest {
      public static void main(String[] args) {
            Thread start = Thread.START;
            System.out.println(start);
            Thread dead = Thread.DEAD;
            System.out.println(dead);
      }
}

Output :

START
DEAD

package com.jaladhi;
import java.util.Scanner;
public enum Directions {
      EAST, WEST, NORTH, SOUTH
}
public class DirectionDemo {
      public static void main(String [ ] args){
            Directions dir = Directions.NORTH;
            if(dir == Directions.EAST) {
                  System.out.println("Direction: East");
            } else if(dir == Directions.WEST) {
                  System.out.println("Direction: West");
            } else if(dir == Directions.NORTH) {
                  System.out.println("Direction: North");
            } else {
                  System.out.println("Direction: South");
            }
      }
}

Java Enums Example (Inside Enums)

package com.jaladhi;
import java.util.Scanner;
public class ThreadTest {
enum Thread {
      START, RUNNING, WAITING, DEAD;
}
public static void main(String[] args) {
            Thread start = Thread.START;
            System.out.println(start);
            Thread dead = Thread.DEAD;
            System.out.println(dead);
      }
}

Output :

START
DEAD