TreeMap ceilingEntry() and ceilingKey() methods in Java
There are two variants of ceilingEntry() in Java.util.TreeMap, both are discussed in this article.
1. ceilingEntry(K Key) : It is used to return 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 ceilingEntry(K key) Parameters : key : The key to be matched. Return Value : It returns the entry with the least key greater than or equal to key, and null if there is no such key. Exception : ClassCastException : It throws the exception if the specified key cannot be compared with the keys currently in the map. NullPointerException : It throws the exception if the specified key is null.
// Java code to demonstrate the working of // ceilingEntry() import java.io.*; import java.util.*; public class ceilingEntry1 { public static void main(String[] args) { // Declaring the tree map of Integer and String TreeMap<Integer, String> treemap = new TreeMap<Integer, String>(); // assigning the values in the tree map // using put() treemap.put( 2 , "two" ); treemap.put( 7 , "seven" ); treemap.put( 3 , "three" ); // Use of ceilingEntry() // returns 7=seven ( next greater key-value) System.out.println( "The next greater key-value of 5 is : " + treemap.ceilingEntry( 5 )); // returns "null" as no value present // greater than or equal to number System.out.println( "The next greater key-value of 8 is : " + treemap.ceilingEntry( 8 )); } } |
Output:
The next greater key-value of 5 is : 7=seven The next greater key-value of 8 is : null
2. ceilingKey(K key) : This has also the same work as that of the upper one but the only difference is that it does not contains the mapped-keys.It simply returns the least key greater or equal to the given key, else returns NULL.
Syntax : public K ceilingKey(K key) Parameters : key : The key to be matched. Return Value : It returns the entry with the least key greater than or equal to key, and null if there is no such key. Exception: ClassCastException : It throws the exception if the specified key cannot be compared with the keys currently in the map. NullPointerException : It throws the exception if the specified key is null.
// Java code to demonstrate the working of // ceilingKey() import java.io.*; import java.util.*; public class ceilingKey1 { public static void main(String[] args) { // Declaring the tree map of Integer and String TreeMap<Integer, String> treemap = new TreeMap<Integer, String>(); // assigning the values in the tree map // using put() treemap.put( 2 , "two" ); treemap.put( 7 , "seven" ); treemap.put( 3 , "three" ); // Use of ceilingKey() // returns 7 ( next greater key) System.out.println( "The next greater key of 5 is : " + treemap.ceilingKey( 5 )); // returns "null" as no key present // greater than or equal to number System.out.println( "The next greater key of 8 is : " + treemap.ceilingKey( 8 )); } } |
Output:
The next greater key of 5 is : 7 The next greater key of 8 is : null