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Java TreeMap ceilingKey() Method with Example

TreeMap Class ceilingKey() method: Here, we are going to learn about the ceilingKey() method of TreeMap Class with its syntax and example.
Submitted by Preeti Jain, on February 19, 2020

TreeMap Class ceilingKey() method

• ceilingKey() method is available in java.util package.
• ceilingKey() method is used to return the lower-key element larger than or equal to the given key element (ele) otherwise it returns null.
• ceilingKey() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• ceilingKey() method may throw an exception at the time of returning an appropriate key value.
  • ClassCastException: This exception may throw when the given parameter is incompatible.
  • NullPointerException: This exception may throw when the given parameter is null exists.

Syntax:

    public Key ceilingKey(Key ele);

Parameter(s):

• Key ele – represents the key element (ele) to be checked in this TreeMap.

Return value:

The return type of the method is Key, it returns least key value element larger than or equal to the given key element (ele) otherwise it returns null.

Example:

// Java program to demonstrate the example 
// of Key ceilingKey(Key ele) method of TreeMap 

import java.util.*;

public class CeilingKeyOfTreeMap {
    public static void main(String[] args) {
        // Instantiates a TreeMap object
        NavigableMap < Integer, String > tree_map = new TreeMap < Integer, String > ();

        // By using put() method is to add
        // key-value pairs in a TreeMap
        tree_map.put(10, "C");
        tree_map.put(20, "C++");
        tree_map.put(50, "JAVA");
        tree_map.put(40, "PHP");
        tree_map.put(30, "SFDC");

        // By using ceilingKey(35) method is
        // to return the key value mapped with
        // the least key value element greater than or
        // equal to the given key value element i.e. 40 

        System.out.print("tree_map.ceilingKey(35): ");
        System.out.println(tree_map.ceilingKey(35));
    }
}

Output

tree_map.ceilingKey(35): 40