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Java Program to Update value of HashMap using key
In this article, we will understand how to update value of HashMap using key. Java HashMap is a hash table based implementation of Java's Map interface. It is a collection of key-value pairs.
Below is a demonstration of the same −
Suppose our input is −
Input HashMap: {Java=1, Scala=2, Python=3}The desired output would be −
The HashMap with the updated value is: {Java=1, Scala=12, Python=3}Algorithm
Step 1 - START Step 2 - Declare namely Step 3 - Define the values. Step 4 – Create a hashmap of values and initialize elements in it using the ‘put’ method. Step 5 - Display the hashmap on the console. Step 6 - To fetch a specific value, access the hashmap using the key, with the ‘get’ method. Step 7 - Add certain value to the fetched value. Step 8 - Display the updated value on the console. Step 9 - Stop
Example 1
Here, we bind all the operations together under the ‘main’ function.
import java.util.HashMap;
public class Demo {
public static void main(String[] args) {
System.out.println("The required packages have been imported");
HashMap<String, Integer> input_map = new HashMap<>();
input_map.put("Java", 1);
input_map.put("Scala", 2);
input_map.put("Python", 3);
System.out.println("The HashMap is defined as: " + input_map);
int value = input_map.get("Scala");
value = value + 10;
input_map.put("Scala", value);
System.out.println("\nThe HashMap with the updated value is: " + input_map);
}
}Output
The required packages have been imported
The HashMap is defined as: {Java=1, Scala=2, Python=3}
The HashMap with the updated value is: {Java=1, Scala=12, Python=3}Example 2
Here, we encapsulate the operations into functions exhibiting object oriented programming.
import java.util.HashMap;
public class Demo {
static void update(HashMap<String, Integer> input_map, String update_string){
int value = input_map.get(update_string);
value = value + 10;
input_map.put("Scala", value);
System.out.println("\nThe HashMap with the updated value is: " + input_map);
}
public static void main(String[] args) {
System.out.println("The required packages have been imported");
HashMap<String, Integer> input_map = new HashMap<>();
input_map.put("Java", 1);
input_map.put("Scala", 2);
input_map.put("Python", 3);
System.out.println("The HashMap is defined as: " + input_map);
String update_string = "Scala";
update(input_map, update_string);
}
}Output
The required packages have been imported
The HashMap is defined as: {Java=1, Scala=2, Python=3}
The HashMap with the updated value is: {Java=1, Scala=12, Python=3}
Updated on: 30-Mar-2022
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