How to Get an Enum Value from a String Value in Java

How to get an enum value from a string value in Java

Yes, Blah.valueOf("A") will give you Blah.A.

Note that the name must be an exact match, including case: Blah.valueOf("a") and Blah.valueOf("A ") both throw an IllegalArgumentException.

The static methods valueOf() and values() are created at compile time and do not appear in source code. They do appear in Javadoc, though; for example, Dialog.ModalityType shows both methods.

How to get Enum value from String value of one of it's attributes

Solution:

@AllArgsConstructor
@Getter
public enum ExternalEnum {
    enum1("red", "1"),
    enum2("black", "2"),
    enum3("blue", "3");

    private String colour;
    private String number;

    // you can call this method with number or name but you have to change 
     //parameter accordingly
    public static ExternalEnum findByNumber(String number) {  
      for(ExternalEnum type : values()) {
         if(type.equals(number)) {
            return type; 
         }
      }              
  }
}

Getting String value from enum in Java

if status is of type Status enum, status.name() will give you its defined name.

Getting java enum by name

Each Java enum has method valueOf(String name) which returns enum by name.

MyEnum foo = MyEnum.valueOf("TOTO");
MyEnum bar = MyEnum.valueOf("ZOZO");

Convert String to equivalent Enum value

Hope you realise, java.util.Enumeration is different from the Java 1.5 Enum types.

You can simply use YourEnum.valueOf("String") to get the equivalent enum type.

Thus if your enum is defined as so:

public enum Day {
    SUNDAY, MONDAY, TUESDAY, WEDNESDAY, 
    THURSDAY, FRIDAY, SATURDAY
}

You could do this:

String day = "SUNDAY";

Day dayEnum = Day.valueOf(day);

How to cast a String value to an Enum value by Class?

It's actually kind of a pain because of the way Enum is declared. You wouldn't be able to call valueOf with a Class<?> (nor e.g. a Class<? extends Enum<?>>). The only way to do it without unchecked casting is to go through getEnumConstants:

public boolean tryCast(String value){
    for(Object o : enumClass.getEnumConstants()) {
        Enum<?> e = (Enum<?>) o;
        if(e.name().equals(value))
            return true;
    }
    return false;
}

If you don't care about the unchecked cast you can do:

try {
    Enum.valueOf( (Class) enumClass, value );
    return true;
} catch(IllegalArgumentException e) {
    return false;
}

But, you know, some people will grumble because it's a raw type. getEnumConstants is probably better anyways since then you don't use exceptions for this kind of thing.

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In addition, since you have a Class<?> you might want to perform a check like

if( !Enum.class.isAssignableFrom(enumClass) )
    return false;

or throw an exception in the constructor.

Java: How to get an enum value to a string?

You can inject the enum's value, as a String:

    public void checkIfRecordIsUsed(String record, testEnum test) {
        List<String> data = new ArrayList<String>();
        Query dataQuery = entityManager.createNativeQuery("select * from DATA where test_a = ?2 and prg_l = ?1");
        dataQuery.setParameter(1, record);
        dataQuery.setParameter(2, test.name());
        if (dataQuery.getResultStream().findAny().isPresent())
            tablesWithRecords.add("DATA");
    }

Getting Enum value by another value

The ENUM types has the method values, which you can use to extract all the enum values and compare their identifier against the one that you have passed by the method parameter, namely:

public MyEnum getEnum(String identifier){
      for(MyEnum e : MyEnum.values())
         if(e.identifier.equals(identifier))
            return e;
      return null;
 }

or even better:

public static Optional<MyEnum> getEnum(String identifier){
        return Arrays.stream(MyEnum.values()).filter(i -> i.identifier.equals(identifier)).findFirst();
}

This way you make it clear on the method signature that you might or not find the enum.

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