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 // 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 // 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 // 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)