Lookup Enum by String Value in Java

In this article, we will understand how to look up enum by string value using Java. An enum is a special "class" that represents a group of constants (unchangeable variables, like final variables). The program will demonstrate how you can convert a string to its corresponding enum value using the valueOf() method, as well as how to print enum values using the enum name() method.

Problem Statement

Write a program in Java to look up enum by string value. Below is a demonstration of the same ?

Input

The string to lookup is: Java

Output

The result is:
JAVA

Different Approaches

Following are the different approaches to look up enum by string value ?

• Using valueOf() method
• Using name() method
  

Enum lookup using valueOf()

Following are the steps to look up an enum by string value using valueOf() ?

• First, we will declare an enum called Languages with constants.
  
• After that, we will create a string variable that contains the input value (e.g., "Java").
  
• Convert the input string to uppercase using the toUpperCase() method.
  
• We will be using the valueOf() method of the Languages enum to match the uppercase string with the enum value.
  
• Print the matched enum value.

Example

Here, we use valueOf() to print the enum values ?

public class Demo {
   public enum Languages {
      JAVA, SCALA, PYTHON, MYSQL
   }
   public static void main(String[] args) {
      String input_string = "Java";
      System.out.println("The string is to lookup is: " +input_string);
      Languages result = Languages.valueOf(input_string.toUpperCase());
      System.out.println("\nThe result is: ");
      System.out.println(result);
   }
}

Output

The string to lookup is: Java

The result is:
JAVA

Printing enum values with .name()

Following are the steps to print enum values using the .name() method ?

• First, we will declare an enum called Languages with constants.
  
• Print a message indicating that you will display all enum values.
  
• Use the .name() method to print each enum value in its string form.
  
• Display the enum values one by one.

Example

Here, we use the .name() function to print the ENUM values ?

enum Languages {
   Java,
   Scala,
   Python,
   Mysql;
}
public class Demo {
   public static void main(String[] args) {
   System.out.println("The values of the ENUM are: ");
   System.out.println(Languages.Java.name());
   System.out.println(Languages.Scala.name());
   System.out.println(Languages.Python.name());
   System.out.println(Languages.Mysql.name());
   }
}

Output

The values of the ENUM are:
Java
Scala
Python
Mysql