Java TreeSet remove() Method

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Description

The Java TreeSet remove(Object o) method is used to remove the specified element from this set if it is present.

Declaration

Following is the declaration for java.util.TreeSet.remove() method.

public boolean remove(Object o)

Parameters

o − This is the object to be removed from this set, if present

Return Value

The method call returns true if this set contained the specified element.

Exception

• ClassCastException − This is thrown if the specified object cannot be compared with the elements currently in this set.

• NullPointerException − This is thrown if the specified element is null and this set uses natural ordering, or its comparator does not permit null elements.

Removing an Element of a TreeSet of Integer Example

The following example shows the usage of Java TreeSet remove() method to remove an entry from the treeset. We've created a TreeSet object of Integer. Then few entries are added using add() method. Using remove() method, an element is removed and tree is printed.

package com.tutorialspoint;

import java.util.TreeSet;

public class TreeSetDemo {
   public static void main(String[] args) {

      // creating a TreeSet 
      TreeSet<Integer> treeset = new TreeSet<>();

      // adding in the tree set
      treeset.add(1);
      treeset.add(13);
      treeset.add(17);
      treeset.add(2);

      // removing 17 from the set
      System.out.println("Remove 17: "+treeset.remove(17));
	  
      // displaying the Tree set data
      System.out.println("Tree set : " + treeset);
   }     
}

Output

Let us compile and run the above program, this will produce the following result.

Remove 17: true
Tree set : [1, 2, 13]

Removing an Element of a TreeSet of String Example

The following example shows the usage of Java TreeSet remove() method to remove an entry from the treeset. We've created a TreeSet object of String. Then few entries are added using add() method. Using remove() method, an element is removed and tree is printed.

package com.tutorialspoint;

import java.util.TreeSet;

public class TreeSetDemo {
   public static void main(String[] args) {

      // creating a TreeSet 
      TreeSet<String> treeset = new TreeSet<>();

      // adding in the tree set
      treeset.add("A");
      treeset.add("C");
      treeset.add("B");
      treeset.add("D");

      // removing B from the set
      System.out.println("Remove B: "+treeset.remove("B"));
	  
      // displaying the Tree set data
      System.out.println("Tree set : " + treeset);
   }     
}

Output

Let us compile and run the above program, this will produce the following result.

Remove B: true
Tree set : [A, C, D]

Removing an Element of a TreeSet of Object Example

The following example shows the usage of Java TreeSet remove() method to remove an entry from the treeset. We've created a TreeSet object of Student. Then few entries are added using add() method. Using remove() method, an element is removed and tree is printed.

package com.tutorialspoint;

import java.util.TreeSet;

public class TreeSetDemo {
   public static void main(String[] args) {

      // creating a TreeSet 
      TreeSet <Student>treeset = new TreeSet<>();

      // adding in the tree set
      treeset.add(new Student(2, "Julie"));
      treeset.add(new Student(1, "Robert"));
      treeset.add(new Student(3, "Adam"));
      treeset.add(new Student(4, "Julia"));

      // removing Adam from the set
      System.out.println("Remove Adam: "+treeset.remove(new Student(3, "Adam")));
	  
      // displaying the Tree set data
      System.out.println("Tree set : " + treeset);
   }     
}
class Student implements Comparable<Student> {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
   
   @Override
   public boolean equals(Object obj) {
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name);
   }

   @Override
   public int compareTo(Student student) {
      return this.rollNo - student.rollNo;
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Remove Adam: true
Tree set : [[ 1, Robert ], [ 2, Julie ], [ 4, Julia ]]