A for-loop to iterate over an enum in Java

user_135178 0
Viewed 502265

I have an enum in Java for the cardinal and intermediate directions:

public enum Direction {
   NORTH,
   NORTHEAST,
   EAST,
   SOUTHEAST,
   SOUTH,
   SOUTHWEST,
   WEST,
   NORTHWEST
}

How can I write a for loop that iterates through each of these enum values?

enums for-loop loops java
9 Answers

.values()

You can call the values() method on your enum.

for (Direction dir : Direction.values()) {
  // do what you want
}

This values() method is implicitly declared by the compiler. So it is not listed on Enum doc.

user_1258440

All the constants of an enum type can be obtained by calling the implicit public static T[] values() method of that type:

 for (Direction d : Direction.values()) {
     System.out.println(d);
 }
user_892660

You can do this as follows:

for (Direction direction : EnumSet.allOf(Direction.class)) {
  // do stuff
}
toluju_124570

If you don't care about the order this should work:

Set<Direction> directions = EnumSet.allOf(Direction.class);
for(Direction direction : directions) {
    // do stuff
}
user_905730

More methods in java 8:

Using EnumSet with forEach

EnumSet.allOf(Direction.class).forEach(...);

Using Arrays.asList with forEach 

Arrays.asList(Direction.values()).forEach(...);
user_13832400

we can use a filter(JAVA 8) like this.

Stream.of(Direction.values()).filter(name -> !name.toString().startsWith("S")).forEach(System.out::println);
user_96322360

Scenario: Let's say, we have a fixed number of card types. Each card type has fees and a joining bonus associated with it.

package enumPkg;

public enum CardTypes {
//Each enum is object
DEBIT(10,20),
CREDIT(0,10),
CRYPTO(5,30);

//Object properties
int fees;
int bonus;

//Initilize object using constructor
CardTypes(int fee, int bonus){
    this.fees = fee;
    this.bonus = bonus;
}

//access object property
public int getFees(){
    return this.fees;
}

public int getBonus(){
    return this.bonus;
}

}

Now to access enum in other class. Follow the below process in java:

package enumPkg;

public class EnumClass {
public static void main(String[] args) {
    CardTypes cardType = CardTypes.CREDIT; //Each enum element is public static final, when accessed returns a object
    System.out.println(cardType);

    System.out.println("Debit card fees : "+CardTypes.DEBIT.getFees());
    System.out.println("Debit card bonus : "+CardTypes.DEBIT.getBonus());

    CardTypes[] cardTypes = CardTypes.values();//return array of CardTypes i.e all enum elements we have defined

    for (CardTypes type : CardTypes.values()) {
        System.out.println(type); //particular enum object
        System.out.println(type.ordinal()); //return enum position
        System.out.println("Bonus : "+type.getBonus()); //return enum object property: Bonus
        System.out.println("Fees  : "+type.getFees());//return enum object property: Fees
    }

}
}

Output:

CREDIT
Debit card fees : 10
Debit card bonus : 20
DEBIT
0
Bonus : 20
Fees  : 10
CREDIT
1
Bonus : 10
Fees  : 0
CRYPTO
2
Bonus : 30
Fees  : 5
user_84877320
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