Vector removeIf() method in Java

Last Updated : 18 Sep, 2018

The removeIf() method of Vector removes all of those elements from Vector which satisfies the condition passed as a parameter to this 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 Vector:

Example 1: To demonstrate removeIf() method on vector which contains a set of Numbers and only the numbers which are divisible by 2 will be removed.

   // Java Program Demonstrate removeIf() 
// method of Vector 
  
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create an Vector which going to 
        // contains a list of Numbers 
        Vector<Integer> Numbers = new Vector<Integer>(); 
  
        // Add Number to list 
        Numbers.add(22); 
        Numbers.add(33); 
        Numbers.add(55); 
        Numbers.add(62); 
  
        // apply removeIf() method 
        // to remove numbers divisible by 2 
        Numbers.removeIf(n -> (n % 2 == 0)); 
  
        System.out.println("All Numbers not divisible by 2 are:"); 
  
        // print list 
        for (int i : Numbers) { 
            System.out.println(i); 
        } 
    } 
} 
 
  

Output:

  All Numbers not divisible by 2 are:  33  55

Example 2: To demonstrate removeIf() method on Vector which contains set of Students Names and to remove all 4 char long name.

   // Java Program Demonstrate removeIf() 
// method of Vector 
  
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create a Vector 
        // containing a list of string values 
        Vector<String> students = new Vector<String>(); 
  
        // Add Strings to list 
        // each string represents student name 
        students.add("Rama"); 
        students.add("Mohan"); 
        students.add("Sohan"); 
        students.add("Rabi"); 
        students.add("Shabbir"); 
  
        // apply removeIf() method 
        // to remove names contains 4 chars 
        students.removeIf(n -> (n.length() == 4)); 
  
        System.out.println("Students name do not contain 4 char are"); 
  
        // print list 
        for (String str : students) { 
            System.out.println(str); 
        } 
    } 
} 
 
  

Output:

  Students name do not contain 4 char are  Mohan  Sohan  Shabbir

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

   // Java Program Demonstrate removeIf() 
// method of Vector 
  
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create a Vector 
        // containing a list of string values 
        Vector<String> students = new Vector<String>(); 
  
        // Add Strings to list 
        // each string represents student name 
        students.add("Rama"); 
        students.add("Mohan"); 
        students.add("Sohan"); 
        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/8/docs/api/java/util/Vector.html#removeIf-java.util.function.Predicate-

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Vector removeIf() method in Java

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