Java Collection containsAll() Method

The containsAll() method of Java Collection Interface returns a Boolean value 'true', if this collection contains all the elements in the invoked collection.

Syntax

Parameters

The parameter 'c' represents the collection to be checked for occurrence in this collection.

Throws

ClassCastException- if the types of the elements in the specified collection are not compatible with this collection.

NullPointerException- if the specified collection is null or it contains one or more null elementsl and this collection does not allow null elements.

Return

The containsAll() method returns Boolean value 'true' if this collection contains all of the elements in the invoked collection, else it returns false.

Example 1

import java.util.ArrayDeque;
import java.util.Collection;
public class JavaCollectionContainsAllExample1 {
    public static void main(String[] args) {
        Collection<String> collection=new ArrayDeque<>();
        collection.add("Himanshu");
        collection.add("Sham");
        collection.add("Rita");
        Collection<String> collection1=new ArrayDeque<>();
        collection1.add("Himanshu");
        collection1.add("Sham");
        collection1.add("Rita");
      
         /*containsAll() method will return a boolean value true if
          all the elements are present in the invoked collection*/
        System.out.println(collection.containsAll(collection1));
    }
}

Test it Now

Output:

true

Example 2

import java.util.ArrayDeque;
import java.util.Collection;
public class JavaCollectionContainsAllExample2 {
    public static void main(String[] args) {
        Collection<String> collection=new ArrayDeque<>();
        collection.add("Himanshu");
        collection.add("Sham");
        collection.add("Rita");
        Collection<Boolean> collection1=new ArrayDeque<>();
        //it will give an exception as it does not support null elements. 
        collection1.add(null);
        
         /*containsAll() method will return a boolean value true if
          all the elements are present in the invoked collection*/
        System.out.println(collection.containsAll(collection1));
    }
}

Test it Now

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.util.ArrayDeque.addLast(ArrayDeque.java:249)
	at java.util.ArrayDeque.add(ArrayDeque.java:423)
	at com.javaTpoint.JavaCollectionContainsAllExample2.main(JavaCollectionContainsAllExample2.java:13)

Example 3

import java.util.ArrayDeque;
import java.util.Collection;
public class JavaCollectionContainsAllExample3 {
    public static void main(String[] args) {
        int capacity=10;
        Collection<String> collection=new ArrayDeque<>();
        collection.add("Himanshu");
        collection.add("Sham");
        collection.add("Rita");
         /*containsAll() method will return a boolean value if the
          all the elements are present in the invoked collection*/
        System.out.println(collection.containsAll(null));
    }
}

Test it Now

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.util.AbstractCollection.containsAll(AbstractCollection.java:317)
	at com.javaTpoint.JavaCollectionContainsAllExample3.main(JavaCollectionContainsAllExample3.java:14)

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