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Java Collections - ArrayDeque.retainAll() Examples

[Last Updated: Dec 10, 2025]

Java Collections Java Java API 

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Class:

java.util.ArrayDeque

java.lang.Objectjava.lang.Objectjava.util.AbstractCollectionjava.util.AbstractCollectionjava.util.CollectionCollectionjava.util.ArrayDequejava.util.ArrayDequejava.util.DequeDequejava.lang.CloneableCloneablejava.io.SerializableSerializableLogicBig

Method:

public boolean retainAll(Collection<?> c)

Removes from this collection all of its elements that are not contained in the specified collection.


Examples


package com.logicbig.example.arraydeque;

import java.util.ArrayDeque;
import java.util.List;
import java.util.Set;

public class RetainAllExample {

    public static void main(String... args) {
        ArrayDeque<Integer> ad = new ArrayDeque<>(List.of(3, 8, 1, 9));
        System.out.println(ad);
        boolean b = ad.retainAll(Set.of(3,1));
        System.out.println(b);
        System.out.println(ad);
    }
}

Output

[3, 8, 1, 9]
true
[3, 1]
JDK 25




package com.logicbig.example.arraydeque;

import java.util.ArrayDeque;
import java.util.List;
import java.util.Set;

public class RetainAllExample2 {

    public static void main(String... args) {
        ArrayDeque<Integer> ad = new ArrayDeque<>(List.of(3, 8, 1, 9));
        System.out.println(ad);
        boolean b = ad.retainAll(Set.of(null));
        System.out.println(b);
        System.out.println(ad);
    }
}

Output

[3, 8, 1, 9]
java.lang.NullPointerException: Cannot read the array length because "elements" is null
    at java.util.Set.of (Set.java:696)
    at com.logicbig.example.arraydeque.RetainAllExample2.main (RetainAllExample2.java:17)
    at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:104)
    at java.lang.reflect.Method.invoke (Method.java:565)
    at org.codehaus.mojo.exec.AbstractExecJavaBase.executeMainMethod (AbstractExecJavaBase.java:402)
    at org.codehaus.mojo.exec.ExecJavaMojo.executeMainMethod (ExecJavaMojo.java:142)
    at org.codehaus.mojo.exec.AbstractExecJavaBase.doExecClassLoader (AbstractExecJavaBase.java:377)
    at org.codehaus.mojo.exec.AbstractExecJavaBase.lambda$execute$0 (AbstractExecJavaBase.java:287)
    at java.lang.Thread.run (Thread.java:1474)
JDK 25




package com.logicbig.example.arraydeque;

import java.util.ArrayDeque;
import java.util.List;

public class RetainAllExample3 {

    public static void main(String... args) {
        ArrayDeque<Integer> ad = new ArrayDeque<>();
        System.out.println(ad);
        boolean b = ad.retainAll(List.of("4"));
        System.out.println(b);
        System.out.println(ad);
    }
}

Output

[]
false
[]
JDK 25

See Also