EnumSet.allOf(Class) in Java

EnumSet.allOf(Class): This method is available in java.util.EnumSet class of Java.

Syntax:

<K> EnumSet<K> java.util.EnumSet.allOf(Class<K> elementType)

This method takes one argument. This method creates an enum set containing all of the elements in the specified element type.

Parameters: One parameter is required for this method.

elementType: the class object of the element type for this enumset.

Returns: An enum set containing all the elements in the specified type.

Throws:

NullPointerException - if elementType is null

Approach 1: When no exception

Java

import java.util.EnumSet;

public class EnumSetallOf {
    public enum Colour {
        RED, GREEN, YELLOW, ORANGE
    };

    public static void main(String[] args) {

        EnumSet<Colour> enumSet = EnumSet.allOf(Colour.class);

        System.out.println(enumSet);

    }
}

Output:

[RED, GREEN, YELLOW, ORANGE]

Approach 2: NullPointerException

Java 

import java.util.EnumSet;

public class EnumSetallOf {
    public enum Colour {
        RED, GREEN, YELLOW, ORANGE
    };

    public static void main(String[] args) {

        EnumSet<Colour> enumSet = EnumSet.allOf(null);

        System.out.println(enumSet);

    }
}

Output:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.lang.Class.getEnumConstantsShared()" because "klass" is null
	at java.base/java.lang.System$2.getEnumConstantsShared(System.java:2170)
	at java.base/java.util.EnumSet.getUniverse(EnumSet.java:408)
	at java.base/java.util.EnumSet.noneOf(EnumSet.java:111)
	at java.base/java.util.EnumSet.allOf(EnumSet.java:132)