AbstractMap putAll() Method in Java with Examples
Last Updated :
26 Oct, 2018
The AbstractMap.putAll() is an inbuilt method of AbstractMap class that is used for the copy operation. The method copies all of the elements i.e., the mappings, from one map into another.
Syntax:
new_abstract_map.putAll(exist_abstract_map)
Parameters: The method takes one parameter exist_abstract_map that refers to the existing map we want to copy from.
Return Value: The method does not return any values.
Exception: The method throws NullPointerException if the map we want to copy from is NULL.
Below programs illustrates the working of AbstractMap.putAll() method:
Program 1: Mapping String Values to Integer Keys.
import java.util.*;
public class Abstract_Map_Demo {
public static void main(String[] args)
{
AbstractMap<Integer, String>
abs_map = new HashMap<Integer, String>();
abs_map.put(10, "Geeks");
abs_map.put(15, "4");
abs_map.put(20, "Geeks");
abs_map.put(25, "Welcomes");
abs_map.put(30, "You");
System.out.println("Initial Mappings are: "
+ abs_map);
AbstractMap<Integer, String>
new_abs_map = new HashMap<Integer, String>();
new_abs_map.putAll(abs_map);
System.out.println("The new map looks like this: "
+ new_abs_map);
}
}
|
Output:
Initial Mappings are: {20=Geeks, 25=Welcomes, 10=Geeks, 30=You, 15=4}
The new map looks like this: {25=Welcomes, 10=Geeks, 20=Geeks, 30=You, 15=4}
Program 2: Mapping Integer Values to String Keys.
import java.util.*;
public class Abstract_Map_Demo {
public static void main(String[] args)
{
AbstractMap<String, Integer>
abs_map = new HashMap<String, Integer>();
abs_map.put("Geeks", 10);
abs_map.put("4", 15);
abs_map.put("Geeks", 20);
abs_map.put("Welcomes", 25);
abs_map.put("You", 30);
System.out.println("Initial Mappings are: "
+ abs_map);
AbstractMap<String, Integer>
new_abs_map = new HashMap<String, Integer>();
new_abs_map.putAll(abs_map);
System.out.println("The new map looks like this: "
+ new_abs_map);
}
}
|
Output:
Initial Mappings are: {4=15, Geeks=20, You=30, Welcomes=25}
The new map looks like this: {Geeks=20, 4=15, You=30, Welcomes=25}
Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.
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