ArrayList removeIf() Method in Java with Examples

The removeIf() method of the ArrayList class removes all elements that satisfy a specified condition (predicate). It provides a concise and efficient way to perform conditional bulk removal without explicitly iterating over the list.

• Introduced in Java 8.
• Uses the Predicate functional interface.
• Supports lambda expressions for concise and readable code.

import java.util.ArrayList;

public class GFG {
    public static void main(String[] args) {

        // create an ArrayList of integers
        ArrayList<Integer> num = new ArrayList<>();

        // Adding numbers to 
        // the ArrayList
        num.add(23);
        num.add(32);
        num.add(45);
        num.add(63);

        // Using removeIf() method to remove 
        // numbers divisible by 3
        num.removeIf(n -> (n % 3 == 0));

        System.out.println(num);
    }
}

[23, 32]

Explanation: In the above example, the removeIf() method evaluates each element using the predicate n -> (n % 3 == 0). Elements divisible by 3 (45 and 63) satisfy the condition and are removed, while the remaining elements stay in the ArrayList.

Syntax

public boolean removeIf(Predicate<? super E> filter)

• Parameter: This method takes a parameter "filter" that specifies the condition for removing elements.
• Return Type: This method returns true if any elements were removed; otherwise, false.
• Exception: This method throws NullPointerException if the specified filter is null.

Examples of Java ArrayList removeIf() Method

Example: Removing Strings that Start with a Specific Character

import java.util.ArrayList;

public class GFG {
    public static void main(String[] args) {

        // Creating an ArrayList of student names
        ArrayList<String> s = new ArrayList<>();

        // Adding student names to the ArrayList
        s.add("Sweta");
        s.add("Gudly");
        s.add("Sohan");
        s.add("Amiya");
        s.add("Ram");

        // Using removeIf() method to 
        // remove names starting with 'S'
        s.removeIf(name -> name.startsWith("S"));

        System.out.println("Students whose names do not start with S:");
        System.out.println(s);
    }
}

Students whose names do not start with S:
[Gudly, Amiya, Ram]

Explanation: Here, the predicate name -> name.startsWith("S") checks whether each string begins with the character 'S'. All matching names are removed, and only the remaining names are displayed.

Example: Removing Empty Strings

import java.util.ArrayList;

public class GFG {

    public static void main(String[] args) {

        ArrayList<String> list = new ArrayList<>();

        list.add("Java");
        list.add("");
        list.add("Python");
        list.add("");
        list.add("C++");

        list.removeIf(String::isEmpty);

        System.out.println(list);
    }
}

[Java, Python, C++]

Explanation: The method reference String::isEmpty removes every empty string from the ArrayList, leaving only the non-empty elements.

Difference Between remove() and removeIf()

Advantages of removeIf()

• Removes multiple matching elements in a single method call.
• Eliminates the need for explicit loops.
• Supports lambda expressions and method references.
• Makes conditional removal concise and readable.
• Reduces boilerplate code.
• Improves code maintainability for filtering operations.