Java TreeSet floor() Method

---

---

Description

The Java TreeSet floor(E e) method is used to return the greatest element in this set less than or equal to the given element, or null if there is no such element.

Declaration

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

public E floor(E e)

Parameters

e − This is the value to be matched.

Return Value

The method call returns the greatest element less than or equal to e, or null if there is no such element.

Exception

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

• ClassCastException − This exception is thrown if the specified element cannot be compared with the elements currently exists in the set.

Getting Floor Entry from the TreeSet of Integer Example

The following example shows the usage of Java TreeSet floor() method to the greatest element in this set less than or equal to the given element in the treeset. We've created a TreeSet object of Integer. Then few entries are added using add() method to the set. Using floor() method, we've received the relevant value and printed it.

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(12);
      treeset.add(11);
      treeset.add(16);
      treeset.add(15);

      // getting the floor value for 13
      System.out.println("Floor value for 13: "+treeset.floor(13));   
   }    
} 

Output

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

Floor value for 13: 12

Getting Floor Entry from the TreeSet of String Example

The following example shows the usage of Java TreeSet floor() method to the greatest element in this set less than or equal to the given element in the treeset. We've created a TreeSet object of String. Then few entries are added using add() method to the set. Using floor() method, we've received the relevant value and printed it.

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("D");
      treeset.add("F");
      treeset.add("A");
      treeset.add("C");

      // getting the floor value for E
      System.out.println("Floor value for E: "+treeset.floor("E"));   
   }    
} 

Output

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

Floor value for E: D

Getting Floor Entry from the TreeSet of Object Example

The following example shows the usage of Java TreeSet floor() method to the greatest element in this set less than or equal to the given element in the treeset. We've created a TreeSet object of Student objects. Then few entries are added using add() method to the set. Using floor() method, we've received the relevant value and printed it.

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(4, "Julia"));
      treeset.add(new Student(3, "Adam"));
      treeset.add(new Student(1, "Robert"));

      // getting the floor value for Adam
      System.out.println("Floor value for Adam: "+treeset.floor(new Student(3, "Adam")));   
   }    
} 
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.

Floor value for Adam: [ 3, Adam ]