Java TreeSet ceiling() Method

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Description

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

Declaration

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

public E ceiling(E e)

Parameters

e − This is the value to match.

Return Value

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

Exception

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

Getting a Least Element Greater Than Given Element from a TreeSet of Integer Example

The following example shows the usage of Java TreeSet ceiling() method to get the least element in this set greater than or equal to the given element. We've created a TreeSet object of Integer. Then few entries are added using add() method and using ceiling() method, we're retrieving a 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 ceiling value for 13
      System.out.println("Ceiling value for 13: "+treeset.ceiling(13));   
   }     
}

Output

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

Ceiling value for 13: 15

Getting a Least Element Greater Than Given Element from a TreeSet of String Example

The following example shows the usage of Java TreeSet ceiling() method to get the least element in this set greater than or equal to the given element. We've created a TreeSet object of String. Then few entries are added using add() method and using ceiling() method, we're retrieving a 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("12");
      treeset.add("11");
      treeset.add("16");
      treeset.add("15");

      // getting ceiling value for "13"
      System.out.println("Ceiling value for 13: "+treeset.ceiling("13"));   
   }     
}

Output

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

Ceiling value for 13: 15

Getting a Least Element Greater Than Given Element from a TreeSet of Object Example

The following example shows the usage of Java TreeSet ceiling() method to get the least element in this set greater than or equal to the given element. We've created a TreeSet object of String. Then few entries are added using add() method and using ceiling() method, we're retrieving a value and printed it.

package com.tutorialspoint;

import java.util.Iterator;
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(1, "Robert"));
      treeset.add(new Student(2, "Julie"));  
      treeset.add(new Student(3, "Adam"));
      treeset.add(new Student(4, "Julia"));

      // getting ceiling value for "13"
      System.out.println("Ceiling value for 13: "+treeset.ceiling(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.

Ceiling value for 13: [ 3, Adam ]