How to Create a TreeMap in Java and Add Key-Value Pairs in it?
Last Updated :
08 Feb, 2024
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
import java.util.TreeMap;
public class TreeMapExample {
public static void main(String[] args) {
TreeMap<String, Integer> numberMap = new TreeMap<>();
numberMap.put( "One" , 1 );
numberMap.put( "Two" , 2 );
numberMap.put( "Three" , 3 );
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 the java.util
package.
- It defines a class named
TreeMapExample
.
- Inside the
main
method:
- It creates a
TreeMap
named numberMap
with keys of type String
and values of type Integer
.
- Key-value pairs are added to the
numberMap
.
- The contents of the
numberMap
are displayed.
2. Adding Key-Value Pairs:
Java
import java.util.TreeMap;
public class TreeMapExample {
public static void main(String[] args) {
TreeMap<String, String> fruitMap = new TreeMap<>();
fruitMap.put( "Strawberry" , "Red" );
fruitMap.put( "Banana" , "Yellow" );
fruitMap.put( "Kiwi" , "Green" );
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 the java.util
package.
- It defines a class named
TreeMapExample
.
- Inside the
main
method:
- It creates a
TreeMap
named fruitMap
with keys and values of type String
.
- Key-value pairs representing fruits and their colors are added to the
fruitMap
.
- The contents of the
fruitMap
are displayed.z
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