EnumMap put() Method in Java with Examples
Last Updated : 16 Feb, 2024
The Java.util.EnumMap.put() method in Java associates specified key-value pairs.
In simple words, the put() method is used to add or modify entries in the EnumMap. If the values are repeated, the older values are replaced.
Example
Java // Java Program to demonstrate the usage of EnumMap import java.util.EnumMap; // Enumeration representing programming languages enum ProgLang { Java, JavaScript, Python } // Driver Class public class Main { // Main Function public static void main(String[] args) { // Create an EnumMap to store language-program pairs EnumMap<ProgLang, String> PLM = new EnumMap<>(ProgLang.class); // Add entries to the EnumMap PLM.put(ProgLang.Java, "Study at GeeksforGeeks"); PLM.put(ProgLang.JavaScript, "Learn at GeeksforGeeks"); PLM.put(ProgLang.Python, "Practice at GeeksforGeeks"); // Overwrite an entry for Java PLM.put(ProgLang.Java, "Studying at GeeksforGeeks"); // Print the EnumMap System.out.println(PLM); } } Output:
{Java=Studying at GeeksforGeeks, JavaScript=Learn at GeeksforGeeks, Python=Practice at GeeksforGeeks}Syntax
Enum_Map.put(K key, V value)
Parameters
- key - It is the specified key with which the value is associated.
- value - It is the value associated with the specified key.
Returns
returns the old value associated with the specified key.
Exceptions
- NullPointerException- When the specified key is null.
EnumMap put() Method Examples
Let's see some examples of how to use EnumMap put() Method in Java
Example 1
How to put/add new value for the specified key in EnumMap:
Java import java.util.*; // An enum of geeksforgeeks enum GFG { Global_today, India_today, China } class EnumDemo { public static void main(String[] args) { EnumMap<GFG, Integer> mp = new EnumMap<>(GFG.class); // Values are associated mp.put(GFG.Global_today, 799); mp.put(GFG.India_today, 69); // Display the initial map System.out.println("The map is: " + mp); // Stores the old value associated with the key Integer prevValue = mp.put(GFG.India_today, 72); // Prints the old value System.out.println("Previous value: " + prevValue); // Display the final map System.out.println("The final map is: " + mp); } } OutputThe map is: {Global_today=799, India_today=69} Previous value: 69 The final map is: {Global_today=799, India_today=72} Example 2
To show the working of the keyset() method in Java
Java // Java program to demonstrate the working of keySet() import java.util.*; // an enum of geeksforgeeks // ranking globally and in india public enum gfg { Global_today, India_today, China_today } ; class Enum_demo { public static void main(String[] args) { EnumMap<gfg, Integer> mp = new EnumMap<gfg, Integer>(gfg.class); // Values are associated mp.put(gfg.Global_today, 799); mp.put(gfg.India_today, 69); // Display the initial map System.out.println("The map is: " + mp); // Stores the old value associated with the key int prev_value = mp.put(gfg.Global_today, 800); // Prints the old value System.out.println("Previous value: " + prev_value); // Display the final map System.out.println("The final map is: " + mp); } } OutputThe map is: {Global_today=799, India_today=69} Previous value: 799 The final map is: {Global_today=800, India_today=69} Example 3
NullPointerException in EnumMap put() Method
Java import java.util.*; // An enum of geeksforgeeks enum GFG { Global_today, India_today, China } class EnumDemo { public static void main(String[] args) { EnumMap<GFG, Integer> mp = new EnumMap<>(GFG.class); // Values are associated mp.put(GFG.Global_today, 799); mp.put(null, 69); // Display the initial map System.out.println("The map is: " + mp); // Stores the old value associated with the key Integer prevValue = mp.put(GFG.India_today, 72); // Prints the old value System.out.println("Previous value: " + prevValue); // Display the final map System.out.println("The final map is: " + mp); } } Output:
Exception in thread "main" java.lang.NullPointerException
at java.base/java.util.EnumMap.typeCheck(EnumMap.java:743)
at java.base/java.util.EnumMap.put(EnumMap.java:264)
at EnumDemo.main(EnumDemo.java:16)
Read More EnumMap Methods
Whether you are a beginner starting Java programming or an experienced looking to brush up on your Java skills, this tutorial will provide you with a deep understanding of the put function and its uses in Java.
The put method in Java is a fundamental function for EnumMap manipulation. With this guide, you can easily put/add a new element to an EnumMap using the put method.