Two-Dimensional Arrays (Matrices) and Jagged Arrays

Beginner13 min read•Updated: 2026-10-22

🔲 Two-Dimensional and Jagged Arrays in Java

Introduction

A 2D array in Java is not a single contiguous block of memory; it is an "array of arrays" (an array holding references to other array objects). This enables Jagged Arrays where different rows can have different lengths!

📊 Standard 2D Rectangular Matrix

1public class MatrixDemo {
  public static void main(String[] args) {
      int[][] grid = {
          {1, 2, 3},
          {4, 5, 6},
          {7, 8, 9}
      };
8 
      System.out.println("3x3 Matrix Grid:");
      for (int row = 0; row < grid.length; row++) {
          for (int col = 0; col < grid[row].length; col++) {
              System.out.printf("%3d ", grid[row][col]);
          }
          System.out.println();
      }
  }
17}

⚡ Jagged (Ragged) Arrays

1public class JaggedArrayDemo {
  public static void main(String[] args) {
      // An institute batch where 3 teachers have different numbers of students:
      int[][] batchSizes = new int[3][];
5 
      batchSizes[0] = new int[2]; // Teacher 1 has 2 students
      batchSizes[1] = new int[4]; // Teacher 2 has 4 students
      batchSizes[2] = new int[1]; // Teacher 3 has 1 student
9 
      System.out.println("Jagged Array Row Lengths:");
      for (int i = 0; i < batchSizes.length; i++) {
          System.out.println("Row " + i + " length: " + batchSizes[i].length);
      }
  }
15}

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The java.util.Arrays Utility Class (sort, binarySearch, toString, copyOf)

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Array Iteration, Linear Search, and Min/Max Algorithms	The java.util.Arrays Utility Class (sort, binarySearch, toString, copyOf)

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The java.util.Arrays Utility Class (sort, binarySearch, toString, copyOf)

Two-Dimensional Arrays (Matrices) and Jagged Arrays

Beginner13 min read•Updated: 2026-10-22

Study Materials

🔲 Two-Dimensional and Jagged Arrays in Java

Introduction

📊 Standard 2D Rectangular Matrix

1public class MatrixDemo {
  public static void main(String[] args) {
      int[][] grid = {
          {1, 2, 3},
          {4, 5, 6},
          {7, 8, 9}
      };
8 
      System.out.println("3x3 Matrix Grid:");
      for (int row = 0; row < grid.length; row++) {
          for (int col = 0; col < grid[row].length; col++) {
              System.out.printf("%3d ", grid[row][col]);
          }
          System.out.println();
      }
  }
17}

⚡ Jagged (Ragged) Arrays

1public class JaggedArrayDemo {
  public static void main(String[] args) {
      // An institute batch where 3 teachers have different numbers of students:
      int[][] batchSizes = new int[3][];
5 
      batchSizes[0] = new int[2]; // Teacher 1 has 2 students
      batchSizes[1] = new int[4]; // Teacher 2 has 4 students
      batchSizes[2] = new int[1]; // Teacher 3 has 1 student
9 
      System.out.println("Jagged Array Row Lengths:");
      for (int i = 0; i < batchSizes.length; i++) {
          System.out.println("Row " + i + " length: " + batchSizes[i].length);
      }
  }
15}

Next Lesson

The java.util.Arrays Utility Class (sort, binarySearch, toString, copyOf)

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Array Iteration, Linear Search, and Min/Max Algorithms	The java.util.Arrays Utility Class (sort, binarySearch, toString, copyOf)

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next