What is ArrayList.removeIf() method in Java?
The removeIf method will loop through all the elements of the list and remove the elements that match the condition of the removeIf method.
Syntax
public boolean removeIf(Predicate<? super E> filter);
Example
import java.util.ArrayList;class RemoveIf {public static void main( String args[] ) {ArrayList<Integer> numbers = new ArrayList<>();numbers.add(1);numbers.add(-10);numbers.add(30);numbers.add(-3);System.out.println("The numbers list is " + numbers);numbers.removeIf(number -> number < 0);System.out.println("After removing negative elements, the numbers list is => " + numbers);}}
In the code above, we created a numbers ArrayList and added some positive and negative numbers to it.
Then, we passed a removeIf method. The predicate function will be tested against each element of the numbers list.
In the predicate function, we checked if the number < 0. If the predicate function returns true, then the current object will be removed from the list.
Example with a list of objects
import java.util.ArrayList;class RemoveId {public static void main( String args[] ) {ArrayList<User> users = new ArrayList<>();users.add(new User("Ram", 15));users.add(new User("Ralph", 13));users.add(new User("Raj", 25));users.add(new User("Rahul", 24));System.out.println("The users list is");System.out.println(users);users.removeIf( user -> ! user.canVote() );System.out.println("\nAfter removing users who cannot vote, the users list is");System.out.println(users);}}
In the code above, we created a users ArrayList and added some objects of the User class.
Then, we passed a removeIf method on the users list. The predicate function will be tested against each element of the users list.
In the predicate function, we checked if the object does not satisfy the canVote condition defined in the Userclass. If the predicate function returns true, the current object will be removed from the users list.
