In this article, we will add one ArrayList to another ArrayList contents using addAll() method of Collection interface
Adding one ArrayList contents to another ArrayList using addAll method :
Method signature:
boolean addAll(Collection c);
- This method is used to add one ArrayList contents to another ArrayList contents
- Returns true, if this list changed as a result of the call
AddOneArrayListToAnotherArrayList.java
package in.bench.resources.java.collections;
import java.util.ArrayList;
public class AddOneArrayListToAnotherArrayList {
public static void main(String[] args) {
// 1: creating ArrayList object of type String
ArrayList<String> al1 = new ArrayList<String>();
// adding elements to ArrayList object
al1.add("Sundar Pichai");
al1.add("Satya Nadella");
al1.add("Shiv Nadar");
al1.add("Shantanu Narayen");
// Iterating using enhanced for-loop
System.out.println("Iterating original ArrayList\n");
for(String str : al1) {
System.out.println(str);
}
// 2: creating ArrayList object of type String
ArrayList<String> al2 = new ArrayList<String>();
// adding elements to ArrayList object
al2.add("Narayan Murthy");
al2.add("Nandan Nilekeni");
al2.add("Shibulal SD");
boolean boolAddAll = al1.addAll(al2);
System.out.println("\n\nWhether invoking AL changed : "
+ boolAddAll);
// Iterating using enhanced for-loop
System.out.println("\n\nIterating after"
+ " addAll operation\n");
for(String str : al1) {
System.out.println(str);
}
}
}
Output:
Iterating original ArrayList
Sundar Pichai
Satya Nadella
Shiv Nadar
Shantanu Narayen
Whether invoking AL changed : true
Iterating after addAll operation
Sundar Pichai
Satya Nadella
Shiv Nadar
Shantanu Narayen
Narayan Murthy
Nandan Nilekeni
Shibulal SD
Explanation:
From above example, ArrayList
- allows duplicate elements
- null object is allowed
- while iterating insertion-order is maintained
- insertion-order is maintained, even after addAll operation
Related Articles:
- Java – Creating ArrayList using nCopies method of Collections class
- Java – How to get size or length of an ArrayList ?
- Java – Adding element to ArrayList at specified index position
- Java – Remove element from ArrayList at specified index position
- Java – How to delete a element and delete all elements of an ArrayList ?
- Java- How to get sublist from ArrayList ?
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- Java – Comparing two ArrayList objects using containsAll() method
- Java – Adding one ArrayList to another ArrayList using addAll() method
- Java – Replacing ArrayList element with new value using set() method
- Java – How to get maximum element from ArrayList ?
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- Java – Sorting ArrayList in descending order
- Java 8 – Sorting ArrayList using sort() method of List
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- Java – Remove duplicate elements from ArrayList
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References:
- https://docs.oracle.com/javase/tutorial/collections/intro/
- https://docs.oracle.com/javase/tutorial/collections/interfaces/collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Collection.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Enumeration.html
- https://docs.oracle.com/javase/7/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
- https://docs.oracle.com/javase/7/docs/api/java/util/ListIterator.html
Happy Coding !!
Happy Learning !!