DRY - Don' t Repeat Yourself

As the name implies ,our code should not be repeated .

Bad code - DRY Principle not followed

public class Matrix {

    public static void main(String[] args) {

        int[][] matrix = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };
        //Repeated code logic
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }

        int[][] matrix2digit = {
            {11, 12, 13},
            {14, 15, 16},
            {17, 18, 19}
        };
         //Repeated code logic
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                System.out.print(matrix2digit[i][j] + " ");
            }
            System.out.println();
        }
    }
}

Good Code- DRY Principle followed

public class Matrix {
    public static void main(String[] args) {
        int[][] matrix = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        int[][] matrix2digit = {
            {11, 12, 13},
            {14, 15, 16},
            {17, 18, 19}
        };

        printMatrix(matrix);
        printMatrix(matrix2digit);
    }
    // No Repeated code - code is reused.
    private static void printMatrix(int[][] matrix) {
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }
    }
}