Java TreeMap ceilingKey(K key) Example

The ceilingKey(K key) method of java.util.TreeMap class returns the least key greater than or equal to the given key, or null if there is no such key.

Signature

public K ceilingKey(K key)

This method returns the least key greater than or equal to the given key, or null if there is no such key.Throws java.lang.ClassCastException if the specified key cannot be compared with the keys currently in the map and java.lang.NullPointerException if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

Example

The following example shows the usage of java.util.TreeMap.ceilingKey(key) method.

import java.util.Map;
import java.util.TreeMap;

public class ceilingKeyMethodTreeMapExample 
{
    public static void main(String args[])
    {
        // create an empty TreeMap
        TreeMap<Integer,String> treeMap1 = new TreeMap<Integer,String>();
        
        // use put() method to put elements to the TreeMap
        treeMap1.put(1,"Element1");
        treeMap1.put(2,"Element2");
        treeMap1.put(4,"Element4");
        treeMap1.put(5,"Element5");
        
        //Printing the elements of the TreeMap
        System.out.println("**Elements of \"treeMap1\" **");
        for(Map.Entry<Integer,String> entry : treeMap1.entrySet())
        {
            System.out.println("Key : "+entry.getKey()+" Value : "+entry.getValue());
        }
        //Lets get the Ceiling Key for "3"
        System.out.println("Ceiling Key of \"3\" is : "+treeMap1.ceilingKey(3));
    }
}

Output

**Elements of "treeMap1" **
Key : 1 Value : Element1
Key : 2 Value : Element2
Key : 4 Value : Element4
Key : 5 Value : Element5
Ceiling Key of "3" is : 4

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