Create Matrix Example in Java

Introduction

Create Matrix is a classic Java console program that demonstrates the concept with complete source code and sample output. These programs cover your first Java class, constructors, methods and simple OOP building blocks.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

A matrix (plural matrices) is a rectangular array of numbers, symbols, or expressions, arranged in rows and columns that is treated in certain prescribed ways.

Create Matrix Example Program

import java.util.Scanner;
 
class MainClass {
	int matrix[][];
	int row, column;
	void create() {
		Scanner in = new Scanner(System.in);		
		System.out.println("Number of rows :");
		row = Integer.parseInt(in.nextLine());
		System.out.println("Number of columns :");
		column = Integer.parseInt(in.nextLine());
		matrix = new int[row][column];
		System.out.println("Enter the data :");
		for(int i=0; i < row; i++) {
			for(int j=0; j < column; j++) {
				matrix[i][j] = in.nextInt();
			}
		}
	}
	void display() {
		System.out.println("\nThe Matrix is :");
		for(int i=0; i < row; i++) {
			for(int j=0; j < column; j++) {
				System.out.print("\t" + matrix[i][j]);
			}
			System.out.println();
		}
	}
}
 
class CreateMatrix {
	public static void main(String args[]) {
		MainClass obj = new MainClass();
		obj.create();
		obj.display();
	}
}

Sample Output

Number of rows :
4
Number of columns :
3
Enter the data :
1
56
3
7
2
9
4
3
9
3
78
98

The Matrix is :
        1       56      3
        7       2       9
        4       3       9
        3       78      98

When to use

Use this create matrix example when learning or revising core Java syntax.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. import java.util.Scanner; imports a class used later in the program.

3. A Scanner reads typed input from the keyboard (System.in).

4. A println / print call writes text to the console — part of the sample output below.

5. row = Integer.parseInt(in.nextLine()); updates a variable used in the calculation or output.

6. A println / print call writes text to the console — part of the sample output below.

7. column = Integer.parseInt(in.nextLine()); updates a variable used in the calculation or output.

8. A println / print call writes text to the console — part of the sample output below.

Best Practices

• Name classes in PascalCase and follow one public class per file when starting out.
• Keep main short — delegate work to other methods as programs grow.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.