How to Create a TreeMap in Java and Add Key-Value Pairs in it?
In Java, a TreeMap maintains elements in a sorted order as it is an implementation of the SortedMap Interface. It stores key-value pairs in a sorted order. In this article, we will explore the creation of TreeMap in Java and learn the step-by-step process of adding key-value pairs.
Program to Create and Add Key-Value Pairs to a TreeMap in Java
Below is an example of how to create and after that how to add key-value pairs in a TreeMap.
1. Creating a TreeMap
Java
// Java program to create a TreeMap import java.util.TreeMap; public class TreeMapExample { public static void main(String[] args) { // Creating a TreeMap TreeMap<String, Integer> numberMap = new TreeMap<>(); // Adding key-value pairs numberMap.put( "One" , 1 ); numberMap.put( "Two" , 2 ); numberMap.put( "Three" , 3 ); // Displaying the TreeMap System.out.println( "TreeMap: " + numberMap); } } |
Output
TreeMap: {One=1, Three=3, Two=2}
Explanation of the Program:
- In the above program, tt imports the
TreeMap
class from thejava.util
package. - It defines a class named
TreeMapExample
. - Inside the
main
method:- It creates a
TreeMap
namednumberMap
with keys of typeString
and values of typeInteger
. - Key-value pairs are added to the
numberMap
. - The contents of the
numberMap
are displayed.
- It creates a
2. Adding Key-Value Pairs:
Java
// Java program to add key-value pairs in a TreeMap import java.util.TreeMap; public class TreeMapExample { public static void main(String[] args) { // Creating a TreeMap TreeMap<String, String> fruitMap = new TreeMap<>(); // Adding key-value pairs fruitMap.put( "Strawberry" , "Red" ); fruitMap.put( "Banana" , "Yellow" ); fruitMap.put( "Kiwi" , "Green" ); // Displaying the TreeMap System.out.println( "Fruit TreeMap: " + fruitMap); } } |
Output
Fruit TreeMap: {Banana=Yellow, Kiwi=Green, Strawberry=Red}
Explanation of the Program:
- In the above program, it imports the
TreeMap
class from thejava.util
package. - It defines a class named
TreeMapExample
. - Inside the
main
method:- It creates a
TreeMap
namedfruitMap
with keys and values of typeString
. - Key-value pairs representing fruits and their colors are added to the
fruitMap
. - The contents of the
fruitMap
are displayed.z
- It creates a
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