FRQ Test (Period 1) • 4 min read

Initialize a Numerical Keypad

We wrote a Java method called initializedKeypad that initializes a 2D array to represent a numerical keypad.

class NumericalKeypad {
    private static int[][] keypad = //had to be removed because of liquid error but it would normally be the keypad;
    
    public static void main(String args[]) {
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 3; j++) {
                if (keypad[i][j] >= 0) {
                    System.out.print(keypad[i][j] + " ");
                } else {
                    System.out.print("  ");
                }
                
                if (keypad[i][j] == 0) {
                    break;
                }
            }
            System.out.println();
        }
    }
}

NumericalKeypad test = new NumericalKeypad();
NumericalKeypad.main(null);

1 2 3 
4 5 6 
7 8 9 
  0 

Reverse an Array

class ArrayReversal {
    public static void reverseArray(int[] numberArray) {
        for (int i = 0; i < 10; i++) {
            System.out.print(numberArray[i] + " ");
        }
        for (int i = 0; i < 10; i++) {
            System.out.print(numberArray[9-i] + " ");
        }
    }

    public static void main(String[] args) {
        int[] numbers = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
        reverseArray(numbers);
    }
}

ArrayReversal.main(null);

10 9 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 10 

class RandomIntegers {
    private static ArrayList<Integer> initializeRandomList(int n, int min, int max) {
        ArrayList<Integer> randomList = new ArrayList<Integer>(); // initialize ArrayList
        for (int i = 0; i < n; i++) {
            int randomNumber = (int) (Math.random() * (max - min + 1)) + min;
            randomList.add(randomNumber);
        }
        return randomList;
    }

    public static void main(String[] args) {
        System.out.println(initializeRandomList(5, 1, 7));
        System.out.println(initializeRandomList(10, 20, 100));
        System.out.println(initializeRandomList(3, 3000, 100000));
    }
}

RandomIntegers.main(null);

[2, 2, 4, 3, 2]
[49, 29, 29, 90, 73, 38, 85, 86, 29, 47]
[82352, 30836, 86627]