Java 8 | ArrayDeque removeIf() method in Java with Examples

Last Updated : 10 Dec, 2018

The removeIf() method of ArrayDeque is used to remove all those elements from ArrayDeque which satisfies a given predicate filter condition passed as a parameter to the method. This method returns true if some element are removed from the Vector.

Java 8 has an important in-built functional interface which is Predicate. Predicate, or a condition checking function, which checks the given input for a given condition and returns a boolean result for the same indicating whether the condition was met or not.

Syntax:

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

Parameter: This method takes a parameter filter which represents a predicate which returns true for elements to be removed.

Returns: This method returns True if predicate returns true and some elements were removed.

Exception: This method throws NullPointerException if the specified filter is null.

Below programs illustrate removeIf() method of ArrayDeque:

Example 1: To demonstrate removeIf() method on ArrayDeque which contains a set of String and remove strings starts with A.

// Java Program Demonstrate removeIf() 
// method of ArrayDeque 
  
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create an ArrayDeque 
        // containing a list of string values 
        ArrayDeque<String> students = new ArrayDeque<String>(); 
  
        // Add Strings to list 
        // each string represents student name 
        students.add("Aman"); 
        students.add("Sanjeet"); 
        students.add("Amar"); 
        students.add("Rabi"); 
        students.add("Shabbir"); 
  
        // apply removeIf() method 
        // to remove names which start with A 
        students.removeIf(n -> (n.charAt(0) == 'A')); 
  
        System.out.println("Students name do not starts with A"); 
  
        // print list 
        for (String str : students) { 
            System.out.println(str); 
        } 
    } 
} 

Output:

Students name do not starts with A
Sanjeet
Rabi
Shabbir

Example 2: To demonstrate removeIf() method on ArrayDeque which contains set of Students objects to remove all those students who got less than 40 marks.

// Java Program Demonstrate removeIf() 
// method of ArrayDeque 
  
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create an ArrayDeque 
        // containing a list of Student objects 
        ArrayDeque<student> students = new ArrayDeque<student>(); 
  
        // Add student object to list 
        students.add(new student("Aman", 78)); 
        students.add(new student("Amar", 79)); 
        students.add(new student("Suraj", 38)); 
        students.add(new student("Raju", 22)); 
        students.add(new student("Ankit", 76)); 
        students.add(new student("Sanju", 62)); 
  
        // apply removeIf() method 
        // to remove students who scores below 40 
        students.removeIf(n -> (n.marks <= 40)); 
  
        System.out.println("Students list who score above 40"); 
  
        // print list 
        for (student str : students) { 
            System.out.println(str.name + ", " + str.marks); 
        } 
    } 
} 
  
// create student class 
class student { 
  
    public String name; 
    public int marks; 
  
    student(String name, int marks) 
    { 
        this.name = name; 
        this.marks = marks; 
    } 
} 

Output:

Students list who score above 40
Aman, 78
Amar, 79
Ankit, 76
Sanju, 62

Example 3: To demonstrate NullpointerException in removeIf() method.

// Java Program Demonstrate removeIf() 
// method of ArrayDeque 
  
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create an ArrayDeque 
        // containing a list of string values 
        ArrayDeque<String> students = new ArrayDeque<String>(); 
  
        // Add Strings to list 
        // each string represents student name 
        students.add("Aman"); 
        students.add("Sanjeet"); 
        students.add("Amar"); 
        students.add("Rabi"); 
        students.add("Shabbir"); 
  
        try { 
            // apply removeIf() method with null filter 
            students.removeIf(null); 
        } 
        catch (Exception e) { 
            System.out.println("Exception: " + e); 
        } 
    } 
} 

Output:

Exception: java.lang.NullPointerException

Reference: https://docs.oracle.com/javase/10/docs/api/java/util/ArrayDeque.html#removeIf(java.util.function.Predicate)

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