How to Update the Value for an Existing Key in a TreeMap Using put()?

TreeMap is a part of Java Collection that can in-built class of java.util package. In Java, TreeMap is a pre-defined class that implements the NavigableMap interface and extends the AbstractMap class.

• It represents the Key-Value pairs.
• It is part of the Java Collection Framework.
• It is a sorted map based on a red-black tree data structure.

In this article, we will be learning how to update the value for an existing key in a TreeMap using the basic put() method in Java.

Syntax of put() method:

TreeMap.put(key, value)

Where,

• key: It refers to the key element that needs to be inserted into the TreeMap.
• value: It refers to the value of the mapping key.

Program to Update the Value for an Existing Key in a TreeMap

This method is very simple, and it allows to insertion of a new value for an existing key by using the put() method.

Below is the Program to Update the Value for an Existing Key in a TreeMap Using put() in Java:

Java

// Java program to update the value for
// An existing key in a TreeMap using put() method
import java.io.*;
import java.util.*;

// Driver Class
class GFG {
      // Main Function
    public static void main (String[] args)
    {
      // Creating the TreeMap
      TreeMap<Integer, String> treeMap = new TreeMap<>();

      // Inserting the key-pair values into the treeMap
      treeMap.put(1,"GeeksForGeeks");
      treeMap.put(2,"DSA Tutorial");
      treeMap.put(3,"Java Tutorial");
      treeMap.put(4,"Python Tutorial");

      // Print the oringinal TreeMap
      System.out.println("Oringinal TreeMap:"+treeMap);

      // Updating the values for an existing key
      treeMap.put(2,"Full Stack Web Development");

      // Print the updated TreeMap
      System.out.println("Updated TreeMap:"+treeMap);

    }
}

Output

Oringinal TreeMap:{1=GeeksForGeeks, 2=DSA Tutorial, 3=Java Tutorial, 4=Python Tutorial}
Updated TreeMap:{1=GeeksForGeeks, 2=Full Stack Web Development, 3=Java Tutorial, 4=Python Tutorial}

Explanation of the above Program:

• The value for key 2 in the treeMap is used in this program through the usage of the put() method.
• Then it replaced with Full Stack web Development and the original value DSA Tutorial.
• At last, it prints the updated TreeMap.