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 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:
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);
}
} |
The 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 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);
}
} |
The 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
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.