TreeMap floorEntry() Method in Java With Examples

The java.util.TreeMap.floorEntry() method is used to return a key-value mapping associated with the greatest key less than or equal to the given key, or null if there is no such key.

Syntax:

tree_map.floorEntry(K key)

Parameters: This method takes one parameter key to be matched while mapping.

Return Value:  This method returns an entry with the greatest key less than or equal to key, or null if there is no such key.

Exceptions:  

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

Example 1: When there is a key

Java

// Java program to illustrate
// TreeMap floorEntry() method
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {

        // Creating an empty TreeMap
        TreeMap<Integer, String> treemap
            = new TreeMap<Integer, String>();

        // Mapping string values to int keys
        treemap.put(20, "Twenty");
        treemap.put(10, "Ten");
        treemap.put(13, "Thirteen");
        treemap.put(60, "Sixty");
        treemap.put(50, "Fifty");

        System.out.println("The greatest key-value less than 18 is : "
                           + treemap.floorEntry(18));
    }
}

Output

The greatest key-value less than 18 is : 13=Thirteen

Example 2: When there is no such key

Java

// Java program to illustrate
// TreeMap floorEntry() method
import java.util.TreeMap;

public class GFG {
    public static void main(String args[])
    {

         // Creating an empty TreeMap
        TreeMap<Integer, String> treemap
            = new TreeMap<Integer, String>();

        // Mapping string values to int keys
        treemap.put(10, "Akash");
        treemap.put(20, "Pratik");
        treemap.put(30, "Vaibhav");
        treemap.put(40, "Sagar");
        treemap.put(50, "Abhishek");

        // Printing floor entry
        System.out.println("The greatest key-value less than 5 is : "
                           + treemap.floorEntry(5));
    }
}

Output

The greatest key-value less than 5 is : null