Split a List into Two Halves in Java

In this article, we will understand how to split a list into two halves. A list is an ordered collection that allows us to store and access elements sequentially. It contains index-based methods to insert, update, delete, and search the elements. It can also have duplicate elements. We will be using different approaches to split a list into two halves ?

Problem Statement

Write a Java program to split a list into two halves. As demonstrated below ?

Input 

Input list :[Java, Python, JavaScript, Shell, Scala]

Output

The first half of the list is:
[Java, Python]
The second half of the list is:
[JavaScript, Shell, Scala]

Different Approaches

Below are the different approaches to split a list into two halves ?

• Using the Main() method
• Using object-oriented programming

Using the Main() method

The following are the steps to split a list into two halves ?

• We will start by importing ArrayList and List class from java.util package.
• Define the input_list and add elements to it.
• To hold the split halves we will create two new lists, first_list, and second_list.
• Determine the size of the input_list.
• Iterate through the first half of the input_list and add elements to first_list.
• Iterate through the second half of the input_list and add elements to second_list.
• Print the first_list and second_list.

Example

Here, we bind all the operations together under the main() method  ?

import java.util.ArrayList;
import java.util.List;
public class Demo {
   public static void main(String[] args) {
      System.out.println("Required packages have been imported");
      List<String> input_list = new ArrayList<String>();
      input_list.add("Java");
      input_list.add("Python");
      input_list.add("JavaScript");
      input_list.add("Shell");
      input_list.add("Scala");
      System.out.println("The list is defined as " +input_list);
      List<String> first_list = new ArrayList<String>();
      List<String> second_list = new ArrayList<String>();
      int size = input_list.size();
      System.out.println("\nThe first half of the list is: ");
      for (int i = 0; i < size / 2; i++)
         first_list.add(input_list.get(i));
      System.out.println(first_list);
      System.out.println("The second half of the list is: ");
      for (int i = size / 2; i < size; i++)
         second_list.add(input_list.get(i));
      System.out.println(second_list);
   }
}

Output

Required packages have been imported
The list is defined as [Java, Python, JavaScript, Shell, Scala]

The first half of the list is:
[Java, Python]
The second half of the list is:
[JavaScript, Shell, Scala]

Using object-oriented programming

The following are the steps to split a list into two halves ?

• We will start by importing the necessary packages.
• Define a split_list function that takes the input_list as an argument.
• Inside the split_list function, create two new lists, first_list and second_list.
• Determine the size of the input_list.
• Iterate through the first half of the input_list and add elements to first_list.
• Iterate through the second half of the input_list and add elements to second_list.
• Print the contents of first_list and second_list.
• In the main function, define the input_list and add elements to it.
• Call the split_list function with input_list as the argument.

Example

Here, we encapsulate the operations into functions exhibiting object-oriented programming ?

import java.util.ArrayList;
import java.util.List;
public class Demo {
   static void split_list(List<String> input_list) {
      List<String> first_list = new ArrayList<String>();
      List<String> second_list = new ArrayList<String>();
      int size = input_list.size();
      System.out.println("\nThe first half of the list is: ");
      for (int i = 0; i < size / 2; i++)
         first_list.add(input_list.get(i));
      System.out.println(first_list);
      System.out.println("The second half of the list is: ");
      for (int i = size / 2; i < size; i++)
         second_list.add(input_list.get(i));
      System.out.println(second_list);
   }
   public static void main(String[] args) {
      System.out.println("Required packages have been imported");
      List<String> input_list = new ArrayList<String>();
      input_list.add("Java");
      input_list.add("Python");
      input_list.add("JavaScript");
      input_list.add("Shell");
      input_list.add("Scala");
      System.out.println("The list is defined as " +input_list);
      split_list(input_list);
   }
}

Output

Required packages have been imported
The list is defined as [Java, Python, JavaScript, Shell, Scala]

The first half of the list is:
[Java, Python]
The second half of the list is:
[JavaScript, Shell, Scala]