2 requirements not fullfilled, programm working

Question about the task

2048 (Part 5/18)

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Hey, what´s the problem here? The programm is working, it is displaying sometimes 2, sometimes 4 in random cells. I am calling twice the getRandomNumber(SIDE) and once the getRandomNumber(10). Any help would be appreciated! :)

According to the rules, when you start a game, the values of two random cells must be 2 or 4 (with a probability of 90% and 10%, respectively).

To satisfy this requirement, create a createNewNumber() method and call it twice in the createGame() method.

The createNewNumber() method:

1) selects a random cell whose value is 0 in the gameField matrix.

Hint: A "random cell" is a cell with random coordinates. To get a random x coordinate, you need to use a random number between 0 and SIZE. This can be done by calling the getRandomNumber(int) method with SIDE as the argument. For the y coordinate, you need to do something similar. After getting the coordinates, you need to check the cell value and, if it is not 0, then repeat the search for a random cell until you find one whose value is 0;

2) randomly assigns a value of 2 (probability of 90%) or 4 (probability of 10%).

Hint: use the getRandomNumber(int) method with 10 as the argument:

The getRandomNumber(10) method returns a random number between 0 and 9. So it will return the number 9 with a probability of 10%.

- if getRandomNumber(10) returns the number 9, the cell should be assigned the value 4;
- if getRandomNumber(10) returns a number between 0 and 8, the cell should be assigned the value 2.

Requirements:

A private void createNewNumber() method must be created in the Game2048 class.
The createNewNumber() method should call getRandomNumber(SIDE) twice and getRandomNumber(10) once.
The createNewNumber() method must assign a new value of 2 or 4 (with a probability of 90% and 10%, respectively) to a random empty cell in the gameField matrix.
The createGame() method must call the createNewNumber() method twice.

package com.codegym.games.game2048; import com.codegym.engine.cell.*; import javax.naming.SizeLimitExceededException; public class Game2048 extends Game{ private static final int SIDE = 4; private int[][]gameField = new int[SIDE][SIDE]; @Override public void initialize() { setScreenSize(SIDE, SIDE); createGame(); drawScene(); } private void createGame() { createNewNumber(); createNewNumber(); } private void drawScene() { for (int x=0; x < SIDE; x++) { //set color of every cell for (int y=0; y < SIDE; y++) { setCellColor(x, y, Color.WHITE); } } } private void createNewNumber() { int x = getRandomNumber(SIDE); //Choose a random cell int y = getRandomNumber(SIDE); if (gameField[x][y] != 0) { createNewNumber(); //rerun method, if cell is not empty } if (getRandomNumber(10) == 9) gameField[x][y] = 4; //10% chance for a 4 else gameField[x][y] = 2; //90% chance for a 2 setCellValue(x, y, Integer.toString(gameField[x][y])); } }

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Seb

Level 41 , Crefeld, Germany

25 April 2020, 19:47

solution

The problem is on lines 32 to 37. To be more specific, I think that line 36 is not exactly working as you expect it to. Try an approach without using recursion. Maybe a do while loop? Something like: do { // line 32 // line 33 } while (gameField[x][y] != 0); Good luck! ;-)

DeltaPilot12

Level 24 , Berlin, Germany

26 April 2020, 08:28

Thanks a lot Seb! It did not make it work from the first try on, but by commenting out some lines (even the line with setCellValue, which makes no sense in my opinion) and creating a variable for the chance (which also makes no sense, as the getRandomNumber method would have been called also in the if-statement), I somehow got it to work for the validation. That´s what I came up with:

int x;
int y;

do {
    x = getRandomNumber(SIDE);      //Choose a random cell
    y = getRandomNumber(SIDE);
} while(gameField[x][y] != 0);   //which should be empty

int chance = getRandomNumber(10);

if (chance == 9) gameField[x][y] = 4;      //10% chance for a 4
else gameField[x][y] = 2;                  //90% chance for a 2

//setCellValue(x, y, Integer.toString(gameField[x][y]));

Now I will just uncomment the line of SetCellValue, as otherwise I can not see the numbers displayed in the grid. Therefore I think this validation is somehow broken. But thanks for your help, that teached me at least how to use a do-while loop, which was an option, that I was not aware of before! :)

Seb

Level 41 , Crefeld, Germany

26 April 2020, 09:27

Ah, yeah, I didn’t really take line 42 into account beforehand. Very good that you solved that issue too. :-) I don’t think you should integrate it for the next task either though. I think that line just isn’t needed here and it’s also not mentioned in the task requirements - at least in the description for this task… ;-) Oki doki, thanks for the feedback and happy coding.