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Java - convert String to Enum object

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Created by:

Root-ssh

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Short solution:

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public class Example1 {
​
    enum ColorEnum {
        RED,
        GREEN,
        BLUE
    }
​
    public static void main(String[] args) {
​
        String color = "BLUE";
​
        // we use valueOf on our enum class
        ColorEnum colorEnum = ColorEnum.valueOf(color);
​
        System.out.println(colorEnum); // BLUE
    }
}

In java we can simply convert String to enum by using .valueOf() method on our Enum class.

Example:

MyEnumClass.valueOf("MY_ENUM_CONSTANT")

Note:

We need to use the name of enum value exactly like it is defined.

letter size must be the same
if uppercase letters then we need to use uppercase
if lowercase letters then we need to use lowercase
no spaces
no white spaces

If we don't have exact match then we get exception:

java.lang.IllegalArgumentException: No enum constant ...

1. Documentation - Enum valueOf() method

Edit

Syntax	`valueOf(String name)` Called on Enum class eg ColorEnum.valueOf("BLUE")
Parameters	`name` - String, the name of the constant to return
Result	the enum constant of the specified enum type with the specified name Example type: `ColorEnum`
Description	`valueOf` is static method that takes only one parameter and returns enum constant. Usage example: `ColorEnum colorEnum = ColorEnum.valueOf("BLUE");`
Throws	`IllegalArgumentException` – if this enum type has no constant with the specified name (exatch match required - letter size must match, no spaces, no whitespaces)

2. Using Enum value() and String.toUpperCase()

Edit

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public class Example2 {
​
    enum ColorEnum {
        RED,
        GREEN,
        BLUE
    }
​
    public static void main(String[] args) {
​
        String color = "blue";
        color = color.toUpperCase();
​
        ColorEnum colorEnum = ColorEnum.valueOf(color);
        System.out.println(colorEnum); // BLUE
    }
}

Output:

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BLUE

3. Case with No enum constant

Edit

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public class Example3 {
​
    enum ColorEnum {
        RED,
        GREEN,
        BLUE
    }
​
    public static void main(String[] args) {
​
        String color = "WHITE";
        ColorEnum colorEnum = ColorEnum.valueOf(color);
​
        System.out.println(colorEnum);
    }
}

Output:

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Exception in thread "main" java.lang.IllegalArgumentException: 
No enum constant com.dirask.Example3.ColorEnum.WHITE
    at java.lang.Enum.valueOf(Enum.java:238)