- Java.util Package Classes
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- Java.util Package Extras
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- Java.util - Discussion
Java TreeMap floorKey() Method
Description
TheJava TreeMap floorKey(K key) method is used to return the greatest key less than or equal to the given key, or null if there is no such key.
Declaration
Following is the declaration for java.util.TreeMap.floorKey() method.
public K floorKey(K key)
Parameters
key − This is the key to be matched.
Return Value
The method call returns the greatest key less than or equal to key, or null if there is no such key.
Exception
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.
Getting Floor Key based on given Key from a TreeMap of Integer, Integer Pairs Example
The following example shows the usage of Java TreeMap floorKey() method to get greatest key less than or equal to the given key in the map. We've created a TreeMap object of Integer,Integer pairs. Then few entries are added, and using floorKey() we're printing relevant key to the given key.
package com.tutorialspoint; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, Integer> treemap = new TreeMap<>(); // populating tree map treemap.put(2, 2); treemap.put(1, 1); treemap.put(3, 3); treemap.put(6, 6); treemap.put(5, 5); // getting greatest key for key 4 System.out.println("Checking Keys of the map"); System.out.println("Key is: "+ treemap.floorKey(3)); } }
Output
Let us compile and run the above program, this will produce the following result.
Checking values of the map Value is: 3
Getting Floor Key based on given Key from a TreeMap of Integer, String Pairs Example
The following example shows the usage of Java TreeMap floorKey() method to get greatest key less than or equal to the given key in the map. We've created a TreeMap object of Integer,String pairs. Then few entries are added, and using floorKey() we're printing relevant key to the given key.
package com.tutorialspoint; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, String> treemap = new TreeMap<>(); // populating tree map treemap.put(2, "two"); treemap.put(1, "one"); treemap.put(3, "three"); treemap.put(6, "six"); treemap.put(5, "five"); // getting greatest key for key 4 System.out.println("Checking Keys of the map"); System.out.println("Key is: "+ treemap.floorKey(3)); } }
Output
Let us compile and run the above program, this will produce the following result.
Checking Keys of the map Key is: 3
Getting Floor Entry based on given Key from a TreeMap of Integer, Object Pairs Example
The following example shows the usage of Java TreeMap floorKey() method to get the greatest key less than or equal to the given key in the map. We've created a TreeMap object of Integer,Student pairs. Then few entries are added, and using floorKey() we're printing relevant key to the given key.
package com.tutorialspoint; import java.util.TreeMap; public class TreeMapDemo { public static void main(String[] args) { // creating tree map TreeMap<Integer, Student> treemap = new TreeMap<>(); // populating tree map treemap.put(2, new Student(2, "Robert")); treemap.put(1, new Student(1, "Julie")); treemap.put(3, new Student(3, "Adam")); treemap.put(6, new Student(6, "Julia")); treemap.put(5, new Student(5, "Tom")); // getting greatest key for key 4 System.out.println("Checking Keys of the map"); System.out.println("Key is: "+ treemap.floorKey(3)); } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } @Override public boolean equals(Object obj) { if(obj == null) return false; Student s = (Student)obj; return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name); } }
Output
Let us compile and run the above program, this will produce the following result.
Checking Keys of the map Key is: 3
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