How to create a Two Dimensional List in Java

How to create a Two Dimensional List in Java ?

Answer

To create a Two-Dimensional List in Java, you can use the ArrayList class and initialize it with ArrayLists to represent rows and columns.

✐ Examples

1 Create a 2D List of Strings

In this example,

We import the ArrayList class and create a new ArrayList named matrix to represent the 2D list.
Within a loop, we initialize each row of the matrix as a new ArrayList.
We add elements to each row to represent the columns.
Finally, we print the 2D list to the console.

Java Program

import java.util.ArrayList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<List<String>> matrix = new ArrayList<>();
        for (int i = 0; i < 3; i++) {
            matrix.add(new ArrayList<>());
            for (int j = 0; j < 3; j++) {
                matrix.get(i).add("Element " + i + j);
            }
        }
        System.out.println(matrix);
    }
}

Output

[[Element 00, Element 01, Element 02], [Element 10, Element 11, Element 12], [Element 20, Element 21, Element 22]]

2 Create a 2D List of Integers

In this example,

We import the ArrayList class and create a new ArrayList named matrix to represent the 2D list.
Within nested loops, we initialize each element of the matrix with an integer value.
We print the 2D list to the console.

Java Program

import java.util.ArrayList;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        List<List<Integer>> matrix = new ArrayList<>();
        for (int i = 0; i < 3; i++) {
            matrix.add(new ArrayList<>());
            for (int j = 0; j < 3; j++) {
                matrix.get(i).add(i * 3 + j);
            }
        }
        System.out.println(matrix);
    }
}

Output

[[0, 1, 2], [3, 4, 5], [6, 7, 8]]

Summary

In this tutorial, we learned How to create a Two Dimensional List in Java language with well detailed examples.

◀ Previous Next ▶

Java Tutorials

Java How-Tos

How to create a Two Dimensional List in Java

How to create a Two Dimensional List in Java ?

Answer

✐ Examples

1 Create a 2D List of Strings

Java Program

Output

2 Create a 2D List of Integers

Java Program

Output

Summary

More Java Lists Tutorials