Thread: Changing the attribute of an instance object of a class that's declared in another package and whose variable is constructed by its parent class

I need to access contents, but do you know how considering that contents is declared in Grid? I thought about declaring contents in Piece and Board, but I don't know if that will work.

Write a method in the Board class that takes a row and column index and a two-dimensional array as parameters, and checks to see that the non-zero entries of the given array correspond to empty positions on the grid, assuming that the given array's upper left were positioned at the given row and column. You'll use this to determine if a piece can move into a given position.

Here they say 1 2d array as parameters, but I used 2. Do you know any other way. There must be a simple way to do this, but I don't have the knowledge required to find it.

Or do you know an easy way to rework the class architecture? Like putting Grid inside both Board and Piece, but I don't know if I can do that, because I don't know what Grid does exactly. I don't think I can just copy and paste everything inside those 2.

It should be easy to modify it, since the tutorial is for an introductory course. I am pretty sure there is an easy way of doing this, but what is it?

I could access shapes by writing contents inside moveDown(), because the method call was currentPiece.moveDown(), but here I can't really call the method like that. I don't understand is it because Tetris is in a different package? It doesn't seem to be in a different package. They are all in the same package, right? So, why can't I do that?

I know basic inheritance, but this program is a lot more complex, so it kinda different from the examples I saw.

I did write this a long time ago, but I don't know how I would use it in this case:

	public int[][] getContents()
	{
		return contents;
	}

So do I have to do something like this?

void fall() {
 
 
int [][] a = board.getContent();
int [][] b = currentPiece.getContent();
 
		while(legalDown(currentX, currentY, a, b) && isNotOutOfBoundDown(currentX, currentY, a, b))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}

Would that work?

--- Update ---

	void fall() {
 
		int [][] a = board.getContent();
		int [][] b = currentPiece.getContent();
 
		while(legalDown(currentX, currentY, a, b) && isNotOutOfBoundDown(currentX, currentY, a, b))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}
 
		Tetris.sleep(2000);
	}

Well that doesn't work.

	void fall() {
 
		int [][] a = null;
		int [][] b = null;
 
		while(legalDown(currentX, currentY, a, b) && isNotOutOfBoundDown(currentX, currentY, a, b))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}
 
		Tetris.sleep(2000);
	}

more surprisingly, this doesn't work something is wrong with this line:

while(legalDown(currentX, currentY, a, b) && isNotOutOfBoundDown(currentX, currentY, a, b))

I get:

error: cannot find symbol

	public int[][] getContents()
	{
		return contents;
	}

I put this in piece and strangely it compiles.

		int [][] a = board.getContents();
		int [][] b = currentPiece.getContents();

doesn't work even with the getContents() in all 3 classes... so is the problem caused by board and currentPiece? How is that possible though? Both of them are public.

Ok... something is weird...

I get no error when I do this:

	void fall() {
 
		int [][] a = getContents();
		//int [][] b = currentPiece.getContents();
 
		//while(legalDown(currentX, currentY, a, b) && isNotOutOfBoundDown(currentX, currentY, a, b))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}
 
		Tetris.sleep(2000);
	}

Originally Posted by Norm

Again, this is basic OOP programming. Calling a method define in a class from another class is a very basic technique that is used over and over and over in programs.

There should only be one getContents() method. It should be in the class where contents is defined.

Are you sure about that? Because it gives me cannot find symbol when I remove it. It doesn't seem to inherit the method. So how would you go about doing the following:

	void fall() {
 
		int [][] a = Piece.getContents();
		int [][] b = Board.getContents();
 
		while(legalDown(currentX, currentY, contents, contents) && isNotOutOfBoundDown(currentX, currentY, contents, contents))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}
 
		Tetris.sleep(2000);
	}

int [][] a = Piece.getContents();
int [][] b = Board.getContents();
while(legalDown(currentX, currentY, contents, contents) && isNotOutOfBoundDown(currentX, currentY, contents, contents))

these lines give me the same error" cannot find symbol

Wait, I can't reference a non-static variable in a static context... So what am I supposed to do? It will never work, right?

 
		int [][] a = currentPiece.getContents();
		int [][] b = board.getContents();

wait.. these doesn't work, because currentPiece and board aren't created yet? Is that it? So, how do I solve this problem? Do I have to modify fall() in main and pass board and as an arguments and then do the following?

 
		int [][] a = getContents();
		int [][] b = board.getContents();

because getContents work, because of the method call: currentPiece.fall();

--- Update ---

Originally Posted by Norm

Again this problem is a basic OOP programming problem. You're trying to work with code that is past your knowledge. I suggest that you take a break from this project and go back and study the basics.

Write a 30-50 line complete program with 4 classes. One base, two that extend and one driver.
Define a variable in the base class and a getter method for it. In the driver class define instances of each of the classes that extend base class and call the getter method for each instance.

What is the symbol that can not be found.

I just completed an assignment on inheritance. I just need to know how to make this work. This program is a lot more complex than what I had to do.

board.getContents();

doesn't work, because board is created at run-time. that's probably why.

--- Update ---

Ahhh, it works, except this line: while(legalDown(currentX, currentY, a, a) && isNotOutOfBoundDown(currentX, currentY, a, a))

 
	void fall(Board board) {
 
		int [][] a = getContents();
		int [][] b = board.getContents();
 
		while(legalDown(currentX, currentY, a, a) && isNotOutOfBoundDown(currentX, currentY, a, a))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}
 
		Tetris.sleep(2000);
	}

--- Update ---

 
void fall(Board board) {
 
		int [][] a = getContents();
		int [][] b = board.getContents();
 
		while(Board.legalDown(currentX, currentY, a, a) && Board.isNotOutOfBoundDown(currentX, currentY, a, a))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}
 
		Tetris.sleep(2000);
	}

Ok... what the...

error: method legalDown in class Board cannot be applied to given types;

error: method isNotOutOfBoundDown in class Board cannot be applied to given types;

It doesn't make any sense...

public static boolean legalDown(int currentX, int currentY, int[][] board, int[][] shape)

public static boolean isNotOutOfBoundDown(int currentX, int currentY, int[][] board, int[][] shape)

I assume there is something wrong with this:

 
	public int[][] getContents()
	{
		return contents;
	}

There's only 1 getContents in Grid... so what is the problem?

I think I solved most of the problems, but there is something wrong with the getter method...

 
	void fall(Board board) {
 
		int [][] a = getContents();
		int [][] b = board.getContents();
 
		while(Board.dummy(currentX, currentY, a) && Board.isNotOutOfBoundDown(currentX, currentY, a, b))
		{
		currentX--;
		updateLocation();
    	updateSize();
		}
 
		Tetris.sleep(2000);
	}

error: method dummy in class Board cannot be applied to given types;
error: method isNotOutOfBoundDown in class Board cannot be applied to given types;

a and b gives the same error... do you know why?

Microsoft Windows [Version 6.0.6002]
Copyright (c) 2006 Microsoft Corporation. All rights reserved.


C:\Users\->cd C:\Users\-\Desktop\tetris\tocomplete

C:\Users\-\Desktop\tetris\tocomplete>javac Piece.java
Piece.java:77: error: method legalDown in class Board cannot be applied to given
types;
while(Board.legalDown(currentX, currentY, b, a) && Board.isNotOu
tOfBoundDown(currentX, currentY, b, a))
^
required: int,int,int[][],int[][]
found: int,double,int[][],int[][]
reason: actual argument double cannot be converted to int by method invocation
conversion
Piece.java:77: error: method isNotOutOfBoundDown in class Board cannot be applie
d to given types;
while(Board.legalDown(currentX, currentY, b, a) && Board.isNotOu
tOfBoundDown(currentX, currentY, b, a))
^
required: int,int,int[][],int[][]
found: int,double,int[][],int[][]
reason: actual argument double cannot be converted to int by method invocation
conversion
2 errors

C:\Users\-\Desktop\tetris\tocomplete>

--- Update ---

OMFG
OMFG
OMFG

double lol

--- Update ---

man Jcreator is fucking gay

Well great... it compiles, but I get this:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
at Board.legalDown(Board.java:75)
at Piece.fall(Piece.java:77)
at Tetris.dropPiece(Tetris.java:88)
at Tetris.main(Tetris.java:80)

I changed currentY to int, because I don't think it really matters.

--- Update ---

public class collisiontest
{
 
	public static boolean legalDown(int currentX, int currentY, int[][] board, int[][] shape)
	{
	   int x = currentX+1;
	   int y = currentY;
 
	   for (int row = 0; row < 4; row++)
	   {
	   	for(int col = 0; col < 4; col++)
	   	{
 
 
	   		if (shape[row][col] == 1 && board[x+row][y+col] == 0)
	   		{
 
 
	   		}
	   		else
	   		{
	   			if (shape[row][col] == 0 && board[x+row][y+col] == 1)
	   			{
 
	   			}
	   			else
	   			{
 
	   			    if(shape[row][col] ==0 && board[x+row][y+row] == 0)
	   			    {
 
	   			    }
 
	   			    else
	   			    {
 
	   				return false;
	   			    }
	   			}
	   		}
	   	}
	   }
 
 
    return true;
	}
 
 
public static void main(String[] args)
{
  		int [][] m1 =
		{{1,1,0,0},
		 {1,1,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		};
 
 
		int[][] board =
		{{0,0,0,0},
		 {0,0,1,1},
		 {0,0,1,1},
		 {0,0,1,1},
		 {1,1,1,1},
		 {1,1,1,1},
		 {1,1,1,1},
		};
 
			int[][] board3 =
		{{0,0,0,0},
		 {0,0,1,1},
		 {0,0,1,1},
		 {1,0,1,1},
		 {1,1,1,1},
		 {1,1,1,1},
		 {1,1,1,1},
		};
 
		int[][] board2 =
		{{0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {1,1,0,0},
		};
 
int currentX = 1;
int currentY = 0;
 
		System.out.println(legalDown(currentX, currentY, board, m1));
 
		System.out.println(legalDown(currentX, currentY, board3, m1));
 
		System.out.println(legalDown(currentX, currentY, board2, m1));
 
 
 
 
 
 
 
 
 
 
}
}

I don't understand what might be wrong with the code.

Like how come I get an indexoutofbound exception?

Apparently it has to do with this line: if (shape[row][col] == 0 && board[x+row][y+col] == 1)

1
1
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1
1
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1
1
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Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
	at Board.legalDown(Board.java:68)
	at Piece.fall(Piece.java:77)
	at Tetris.dropPiece(Tetris.java:88)
	at Tetris.main(Tetris.java:80)
 
Process completed.

--- Update ---

Ok... I changed this

currentX--;

to that

currentX++;

and I get the reverse and no piece appears... I don't know what is wrong.

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3
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 32
at Board.legalDown(Board.java:75)
at Piece.fall(Piece.java:77)
at Tetris.dropPiece(Tetris.java:88)
at Tetris.main(Tetris.java:80)

Ok... I added the following

	   		if(x + row == 32)
	   		{
	   			return false;
	   		}

and it doesn't give an out of bound exception anymore; however, it freezes...

 
	void fall(Board board) {
 
		int [][] a = getContents();
		int [][] b = board.getContents();
 
 
		while(currentY < 32)
		{
			if(Board.legalDown(currentX, currentY, b, a) && Board.isNotOutOfBoundDown(currentX, currentY, b, a))
			{currentY++;
			updateLocation();
	    	updateSize();
	    	Tetris.sleep(2000);
			}
		}
 
		//Tetris.sleep(2000);
	}

something is wrong with the above

how do i get out of loop after a certain time?

Ok... it works, I will post updates...



Ok so basically I've done the following:

 
	void fall(Board board) {
 
		int [][] a = getContents();
		int [][] b = board.getContents();
 
 
		while(currentY < 28)
		{
			if(Board.legalDown(currentX, currentY, b, a) && Board.isNotOutOfBoundDown(currentX, currentY, b, a))
			{currentY++;
			updateLocation();
	    	updateSize();
	    	Tetris.sleep(2000);
			}
		}
 
		//Tetris.sleep(2000);
	}

The piece should stop at 28, but there's one who kept going until it reached the floor... I think I rotated it, so it might explain the exceptional behavior. I need to fix 2 things, the freezing and the exceptional behaviour and find a way to make the piece go all the way down.

Originally Posted by Norm

Hard coding magic numbers like 28 and 32 makes for hard to maintain and understand code. Try using variables.

How do we debug this. I really have a hard trouble debugging the program and understanding why so many things are going wrong.

It somewhat works, but I need the pieces to go all the way down, and I think there is a problem with updateLocation(), because sometimes it doesn't hit anything and stops moving

public class collisiontest
{
 
	public static boolean legalDownSpec(int currentX, int currentY, int[][] board, int[][] shape, int index)
	{
	   int x = currentX+1;
	   int y = currentY;
 
	   for (int row = 0; row < index; row++)
	   {
	   	for (int col = 0; col < index; col++)
	   	{
 
	   		if (shape[row][col] == 1 && board[x+row][y+col] == 0)
	   		{
 
 
	   		}
	   		else
	   		{
	   			if (shape[row][col] == 0 && board[x+row][y+col] == 1)
	   			{
 
	   			}
	   			else
	   			{
 
	   			    if(shape[row][col] ==0 && board[x+row][y+row] == 0)
	   			    {
 
	   			    }
 
	   			    else
	   			    {
 
	   				return false;
	   			    }
	   			}
	   		}
	   	}
	   }
 
 
    return true;
	}
 
 
 
 
	public static boolean legalDown(int currentX, int currentY, int[][] board, int[][] shape)
	{
	   int x = currentX+1;
	   int y = currentY;
 
 
	   if (x >= 3)
	   {
	   	int index = x;
	   	index = 6-index;
 
	   	return legalDownSpec(currentX, currentY, board, shape, index);
 
	   	//call special code here
	   }
 
	   for (int row = 0; row < 4; row++)
	   {
	   	for(int col = 0; col < 4; col++)
	   	{
 
	   		if (shape[row][col] == 1 && board[x+row][y+col] == 0)
	   		{
 
 
	   		}
	   		else
	   		{
	   			if (shape[row][col] == 0 && board[x+row][y+col] == 1)
	   			{
 
	   			}
	   			else
	   			{
 
	   			    if(shape[row][col] ==0 && board[x+row][y+row] == 0)
	   			    {
 
	   			    }
 
	   			    else
	   			    {
 
	   				return false;
	   			    }
	   			}
	   		}
	   	}
	   }
 
 
    return true;
	}
 
 
public static void main(String[] args)
{
  		int [][] m1 =
		{{1,0,0,0},
		 {1,0,0,0},
		 {1,0,0,0},
		 {1,0,0,0},
		};
 
 
		int[][] board =
		{{0,0,0,0},
		 {0,0,1,1},
		 {0,0,1,1},
		 {0,0,1,1},
		 {0,0,1,1},
		 {0,0,1,1},
		 {1,0,1,1},
		};
 
			int[][] board3 =
		{{0,0,0,0},
		 {0,0,1,1},
		 {0,0,1,1},
		 {0,0,1,1},
		 {0,0,1,1},
		 {0,0,1,1},
		 {1,1,1,1},
		};
 
		int[][] board2 =
		{{0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		 {0,0,0,0},
		};
 
int currentX = 7; //3 causes exception
int currentY = 0;
 
		System.out.println(legalDown(currentX, currentY, board, m1));
 
		System.out.println(legalDown(currentX, currentY, board3, m1));
 
		System.out.println(legalDown(currentX, currentY, board2, m1));
 
 
 
 
 
 
 
 
 
 
}
}

Any tips. Do you know what's causing the problem?

I did add a new method, but I get an Array Out Of Bound Exception even earlier.

Any suggestion?

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 27
at Board.legalDownSpec(Board.java:74)
at Board.legalDown(Board.java:110)
at Piece.fall(Piece.java:92)
at Tetris.dropPiece(Tetris.java:88)
at Tetris.main(Tetris.java:80)

line74: if (shape[row][col] == 0 && board[x+row][y+col] == 1)
line110: return legalDownSpec(currentX, currentY, board, shape, index);

I don't get any exception in the console program, but in the Tetris program. It's another story. I don't know, can you look at the code and see what's wrong?

 
	   if (x >= 28)
	   {
	   	int index = x;
	   	index = 31-index;
 
	   	return legalDownSpec(currentX, currentY, board, shape, index);
 
	   	//call special code here
	   }

I changed a bit of code before putting it in Board.

 
	   		if(shape[row][col] == 1 && row == 7)
	   		{
	   			return false;
	   		}

would this fix it? if row indexes was between 6 and 0, wouldn't this cause an arrayoutofbound?

--- Update ---

Originally Posted by Norm

The posted code still has the confusion between using x,y and row,col. It would be less confusing if the code worked with a single style of names.
To me x is a column value and y is a row value. In a 2 dim array, the first dim is the row, the second the column.
This code makes for confusion:

 board[x+row][y+col]

mixing x (a column) with row

Also this makes no sense:

int currentX = 7; //3 causes exception

none of the arrays have 7 columns.

oh that's inside my console program... ah sorry for the confusion, i kinda messed up, and just did a quick fix...

which was

currentX = y

and current Y = x or something along the same line