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);        }    }} |
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);        }    }} |
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);        }    }} |
Exception: java.lang.NullPointerException
