Java: Check if enum contains a given string?

Question

Here\'s my problem - I\'m looking for (if it even exists) the enum equivalent of ArrayList.contains();.

Here\'s a sample of my code problem:

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Answer 1

Java Streams provides elegant way to do that

Stream.of(MyEnum.values()).anyMatch(v -> v.name().equals(strValue))

Returns: true if any elements of the stream match the provided value, otherwise false

Answer 2

It is an enum, those are constant values so if its in a switch statement its just doing something like this:

case: val1
case: val2

Also why would you need to know what is declared as a constant?

Answer 3

This combines all of the approaches from previous methods and should have equivalent performance. It can be used for any enum, inlines the "Edit" solution from @Richard H, and uses Exceptions for invalid values like @bestsss. The only tradeoff is that the class needs to be specified, but that turns this into a two-liner.

import java.util.EnumSet;

public class HelloWorld {

static enum Choices {a1, a2, b1, b2}

public static <E extends Enum<E>> boolean contains(Class<E> _enumClass, String value) {
    try {
        return EnumSet.allOf(_enumClass).contains(Enum.valueOf(_enumClass, value));    
    } catch (Exception e) {
        return false; 
    }
}

public static void main(String[] args) {
    for (String value : new String[] {"a1", "a3", null}) {
        System.out.println(contains(Choices.class, value));
    }
}

}

Answer 4

Why not combine Pablo's reply with a valueOf()?

public enum Choices
{
    a1, a2, b1, b2;

    public static boolean contains(String s) {
        try {
            Choices.valueOf(s);
            return true;
        } catch (Exception e) {
            return false;
        }
}

Answer 5

you can also use : com.google.common.base.Enums

Enums.getIfPresent(varEnum.class, varToLookFor) returns an Optional

Enums.getIfPresent(fooEnum.class, myVariable).isPresent() ? Enums.getIfPresent(fooEnum.class, myVariable).get : fooEnum.OTHERS

Answer 6

This approach can be used to check any Enum, you can add it to an Utils class:

public static <T extends Enum<T>> boolean enumContains(Class<T> enumerator, String value)
{
    for (T c : enumerator.getEnumConstants()) {
        if (c.name().equals(value)) {
            return true;
        }
    }
    return false;
}

Use it this way:

boolean isContained = Utils.enumContains(choices.class, "value");