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