Java TreeMap - ceilingEntry() Method

The java.util.TreeMap.ceilingEntry() method returns a key-value mapping associated with the least key greater than or equal to the given key, or null if there is no such key.

Syntax

public Map.Entry<K,V> ceilingEntry(K key)

Here, K and V are the type of key and value respectively maintained by the container.

Parameters

Return Value

Returns an entry with the least key greater than or equal to key, or null if there is no such key.

Exception

• Throws ClassCastException, if the specified key cannot be compared with the keys currently in the map.
• Throws NullPointerException, if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys.

Example:

In the example below, the java.util.TreeMap.ceilingEntry() method returns the key-value mapping associated with the least key greater than or equal to the given value.

import java.util.*;

public class MyClass {
  public static void main(String[] args) {
    //creating a treemap
    TreeMap<Integer, String> MyMap = new TreeMap<Integer, String>();

    //populating the map
    MyMap.put(102, "John");
    MyMap.put(103, "Marry");
    MyMap.put(101, "Kim");
    MyMap.put(104, "Jo");
    MyMap.put(105, "Sam");

    //printing the map
    System.out.println("MyMap contains: " + MyMap); 

    //printing the key-value mapping for the 
    //least key greater than or equal to key=95.
    System.out.println("Ceiling Entry for 95 is: " + MyMap.ceilingEntry(95));     
  }
}

The output of the above code will be:

MyMap contains: {101=Kim, 102=John, 103=Marry, 104=Jo, 105=Sam}
Ceiling Entry for 95 is: 101=Kim