Enum in Java

Enum In Java

Enum is a class used to represent fix number of constant values.

Syntax

Syntax
enum VariableName{
// Data Member goes Here
member1, member2, member3, ....., member n
};

Example

enum SystemError { badFileName, timeOut, resourceNotAvailable };
public class Main {
    public static void main(String[] args) {
        printError(SystemError.badFileName);
    }
   static void printError(SystemError e) {
        if (e == SystemError.badFileName) {
            System.out.println("This is Bad File name Error");
        } else if (e == SystemError.resourceNotAvailable) {
            System.out.println("Resources not available.");
        } else if (e == SystemError.resourceNotAvailable) {
            System.out.println("No Resources available");
        }
    }
}

Show Output

Here, enum SystemError means our own name SystemError where we can write multiple errors inside curly brackets.
printError is a function that takes SystemError as a parameter and prints its custom message according to the error.
In main method we are calling printError function with arguments SystemError.badFileName. It prints This is bad File name error.

Why should you use Enum in Java?

When a method parameter can only take a small set of possible values like (male, female other) or (badFileName, timeOut, resourceNotAvailable). If you use enums, you increase compile-time checking and avoid errors from passing in invalid constants. You can only use what you defined.

Print All Enum Items

enum SystemError { badFileName, timeOut, resourceNotAvailable };
public class Main {
    public static void main(String[] args) {
       for(SystemError s: SystemError.values()){
           System.out.println(s);
       }
    }

}

Show Output