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Java Program to Merge two lists
In this article, we will understand how to merge two lists. A list is an ordered collection that allows us to store and access elements sequentially. It contains the index-based methods to insert, update, delete and search the elements. It can also have the duplicate elements.
Below is a demonstration of the same −
Suppose our input is −
First list: [45, 60, 95] Second list: [105, 120]
The desired output would be −
The list after merging the two lists: [45, 60, 95, 105, 120]
Algorithm
Step 1 - START Step 2 - Declare three integer lists namely input_list_1, input_list_2 and result_list. Step 3 - Define the values. Step 4 - Use result_list.addAll(input_list_1) to add all the elements of the input_list_1 to the result list. Step 5 - Use result_list.addAll(input_list_2) to add all the elements of the input_list_2 to the result list. Step 6 - Display the result_list. Step 7 - Stop
Example 1
Here, we bind all the operations together under the ‘main’ function.
import java.util.ArrayList;
import java.util.List;
public class Demo {
public static void main(String[] args) {
List<Integer> input_list_1 = new ArrayList<>();
input_list_1.add(45);
input_list_1.add(60);
input_list_1.add(95);
System.out.println("The first list is defined as: " + input_list_1);
List<Integer> input_list_2 = new ArrayList<>();
input_list_2.add(105);
input_list_2.add(120);
System.out.println("The second list is defined as: " + input_list_2);
List<Integer> result_list = new ArrayList<>();
result_list.addAll(input_list_1);
result_list.addAll(input_list_2);
System.out.println("\nThe list after merging the two lists: " + result_list);
}
}Output
The first list is defined as: [45, 60, 95] The second list is defined as: [105, 120] The list after merging the two lists: [45, 60, 95, 105, 120]
Example 2
Here, we encapsulate the operations into functions exhibiting object-oriented programming.
import java.util.ArrayList;
import java.util.List;
public class Demo {
static void merge(List<Integer> input_list_1, List<Integer> input_list_2){
List<Integer> result_list = new ArrayList<>();
result_list.addAll(input_list_1);
result_list.addAll(input_list_2);
System.out.println("\nThe list after merging the two lists: " + result_list);
}
public static void main(String[] args) {
List<Integer> input_list_1 = new ArrayList<>();
input_list_1.add(45);
input_list_1.add(60);
input_list_1.add(95);
System.out.println("The first list is defined as: " + input_list_1);
List<Integer> input_list_2 = new ArrayList<>();
input_list_2.add(105);
input_list_2.add(120);
System.out.println("The second list is defined as: " + input_list_2);
merge(input_list_1, input_list_2);
}
}Output
The first list is defined as: [45, 60, 95] The second list is defined as: [105, 120] The list after merging the two lists: [45, 60, 95, 105, 120]
Updated on: 30-Mar-2022
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