Java ArrayList.removeIf() – Syntax & Examples

Java ArrayList.removeIf() – Examples

In this tutorial, we will learn about the Java ArrayList.removeIf() method, and learn how to use this method to remove those elements that pass through a given filter or pass the given predicate, with the help of examples.

removeIf(filter)

ArrayList.removeIf() removes all of the elements of this collection that satisfy the given predicate.

Syntax

The syntax of removeIf() method is

removeIf(Predicate<? super E> filter)

where

Returns

The method returns boolean value.

Example 1 – removeIf(filter)

In this example, we will use ArrayList.removeIf() method to remove all of the elements from the ArrayList that has a string length of 3.

Java Program

import java.util.ArrayList;
import java.util.Arrays;
import java.util.function.Predicate;

public class Example {
	public static void main(String[] args) {
		ArrayList<String> arrayList = new ArrayList<String>(
				Arrays.asList("abc", "ab", "cde", "defg", "abcd", "eee"));		
		
		Predicate<String> filter = str -> (str.length() == 3);
		
		System.out.println("Original ArrayList          : " + arrayList);
		boolean value = arrayList.removeIf(filter);
		System.out.println("Returned value : " + value);
		System.out.println("ArrayList after removeIf()  : " + arrayList);
	}
}

Output

Original ArrayList          : [abc, ab, cde, defg, abcd, eee]
Returned value : true
ArrayList after removeIf()  : [ab, defg, abcd]

Example 2 – removeIf(filter)

In this example, we will use ArrayList.removeIf() method to remove all of the elements from the ArrayList that are odd numbers.

Java Program

import java.util.ArrayList;
import java.util.Arrays;
import java.util.function.Predicate;

public class Example {
	public static void main(String[] args) {
		ArrayList<Integer> arrayList = new ArrayList<Integer>(
				Arrays.asList(1,2, 3, 4, 5, 6, 7, 8));		
		
		Predicate<Integer> filter = n -> (n%2 == 1);
		
		System.out.println("Original ArrayList          : " + arrayList);
		boolean value = arrayList.removeIf(filter);
		System.out.println("Returned value : " + value);
		System.out.println("ArrayList after removeIf()  : " + arrayList);
	}
}

Output

Original ArrayList          : [1, 2, 3, 4, 5, 6, 7, 8]
Returned value : true
ArrayList after removeIf()  : [2, 4, 6, 8]

Conclusion

In this Java Tutorial, we have learnt the syntax of Java ArrayList.removeIf() method, and also learnt how to use this method with the help of examples.