AbstractMap put() Method in Java with Examples
The AbstractMap put() method inserts a mapping into an AbstractMap. This means we can add a specific key and its value, into a particular map. If an existing key is passed, then the previous value gets replaced by the new value. If a new pair is passed, then the pair gets inserted as a whole.
Example:
Java
import java.util.*; public class GFG { public static void main(String[] args) { // Creating an empty AbstractMap AbstractMap<Integer, String> absMap = new HashMap<>(); // Mapping string values to int keys absMap.put( 1 , "Java" ); absMap.put( 2 , "JavaScript" ); absMap.put( 3 , "Python" ); // Displaying the AbstractMap System.out.println( "Initial Mappings are: " + absMap); // Inserting existing key along with new value String returnedValue = absMap.put( 3 , "Beginner" ); // Verifying the returned value System.out.println( "Returned value is: " + returnedValue); // Displaying the new map System.out.println( "New map is: " + absMap); } } |
Output:
Initial Mappings are: {1=Java, 2=JavaScript, 3=Python}
Returned value is: Python
New map is: {1=Java, 2=JavaScript, 3=Beginner}
Syntax
AbstractMap.put(key, value)
Parameters
- key: This refers to the key element that needs to be inserted into the Map for mapping.
- value: This refers to the value that the above key would map into.
Returns
- If an existing key is passed then the previous value gets returned.
- If a new pair is passed, then NULL is returned.
Exceptions
- NullPointerException– When the specified key is null.
AbstractMap put() Method Examples
Let’s see some examples of how to use the Java AbstractMap put() method in Java.
Example 1:
How to add a new element in AbstractMap with Java put() function (passing an existing key).
Java
import java.util.*; public class AbstractMapDemo { public static void main(String[] args) { // Creating an empty AbstractMap AbstractMap<Integer, String> absMap = new HashMap<>(); // Mapping string values to int keys absMap.put( 10 , "Beginner" ); absMap.put( 15 , "4" ); absMap.put( 20 , "Beginner" ); absMap.put( 25 , "Welcomes" ); absMap.put( 30 , "You" ); // Displaying the AbstractMap System.out.println( "Initial Mappings are: " + absMap); // Inserting existing key along with new value String returnedValue = absMap.put( 20 , "All" ); // Verifying the returned value System.out.println( "Returned value is: " + returnedValue); // Displaying the new map System.out.println( "New map is: " + absMap); } } |
Initial Mappings are: {20=Beginner, 25=Welcomes, 10=Beginner, 30=You, 15=4} Returned value is: Beginner New map is: {20=All, 25=Welcomes, 10=Beginner, 30=You, 15=4}
Example 2:
Adding a new element in AbstractMap (passing a new key).
Java
import java.util.*; public class AbstractMapDemo { public static void main(String[] args) { // Creating an empty AbstractMap AbstractMap<Integer, String> absMap = new HashMap<>(); // Mapping string values to int keys absMap.put( 10 , "Beginner" ); absMap.put( 15 , "4" ); absMap.put( 20 , "Beginner" ); absMap.put( 25 , "Welcomes" ); absMap.put( 30 , "You" ); // Displaying the AbstractMap System.out.println( "Initial Mappings are: " + absMap); // Inserting a new key-value pair String returnedValue = absMap.put( 50 , "All" ); // Verifying the returned value System.out.println( "Returned value is: " + returnedValue); // Displaying the new map System.out.println( "New map is: " + absMap); } } |
Initial Mappings are: {20=Beginner, 25=Welcomes, 10=Beginner, 30=You, 15=4} Returned value is: null New map is: {50=All, 20=Beginner, 25=Welcomes, 10=Beginner, 30=You, 15=4}
Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.
Read More AbstractMap 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 AbstractMap put function and its uses in Java.
The AbstractMap put() method in Java is a fundamental function for AbstractMap manipulation. With this guide, you can easily add/put new elements to AbstractMap using the AbstractMap put function.
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