Question

Do anyone knows how to write this in java?   

You are allowed to use the following methods from the Java API:

• class String
  • length
  • charAt
• class StringBuilder
  • length
  • charAt
  • append
  • toString
• class Character
  • any method

1. moveXDownLeft takes a char and a two dimensional array of char as input and returns nothing:
   The method should find the first occurrence of the char in the array (searching from "top" to "bottom" and "left" to "right"), and it should slide that character in the array down and to the left as far as it can go. Any characters on that diagonal are slide up and to the right to fill. Do not use Strings to solve this problem.

   > char[][] board = {{'a','b','c','X'},{'d'},{'e','f','g','h'},{'i','j','k'},{'l','m','n','o'}};
   > HW2.moveXDownLeft('X', board)
   > board
   { { a, b, c, f }, { d }, { e, i, g, h }, { X, j, k }, { l, m, n, o } }
   

Answer 1

Steps Followed:
-> Searched Location of X
-> Moved X to left down
-> Printed resulting Array
Code: (Text File Also Included in End)
MyProgram.java (Main Class)

HW2.java

Result:

Code:
MyProgram.java (Main Class)

public class MyProgram {

    public static void main(String[] args) {
        char[][] board = {{'a', 'b', 'c', 'X'},
                           {'d'},
                           {'e', 'f', 'g', 'h'},
                           {'i', 'j', 'k'},
                           {'l', 'm', 'n', 'o'}};
      
        HW2.moveXDownLeft('X', board);
    
    }

}
HW2.java

public class HW2 {

    // Move Down Left Function
    public static void moveXDownLeft(char X, char[][] board) {
        // Variable Initilization For Store location of X
        int valueColumn = -1;
        int valueRow = -1;
        Boolean found = false;

        // Searching X array by array
        int i = 0;
        for (char[] semiArray : board) {
            // If Find X break Loop
            if (found) {
                break;
            }

            int j = 0;
            for (char arrayValue : semiArray) {
                if (!found) {
                    // Checking if arrayValue is equal To X
                    if (arrayValue == X) {
                        valueRow = i;
                        valueColumn = j;
                        found = true;
                        break;
                    }
                }
                j++;
            }
            i++;
        }

        // Moving Down X
        int col = valueColumn;
        for (int row = (valueRow + 1); row < board.length; row++) {

            // Checking if we reached left end
            if (col > 0) {
                char[] semiArray = board[row];
                // Checking if row has space for move X
                if (semiArray.length >= col) {
                    // Swapping X
                    char temp = board[row][col - 1];
                    board[row][col - 1] = X;
                    board[valueRow][valueColumn] = temp;

                    // Saving new Location of X
                    valueColumn = col - 1;
                    valueRow = row;

                }
                col = col - 1;
            } else {
                break;
            }
        }

        //Printing Resulting Array
        System.out.println("{");
        for (char[] semiArray : board) {
            System.out.print("{");
            int v = 0;
            for (char arrayValue : semiArray) {
                System.out.print(arrayValue);
                if (v < semiArray.length - 1) {
                    System.out.print(",");
                }
            }
            System.out.println("}");
        }
        System.out.println("}");
    }

}