How to change the state of each cell using a 2D boolean array

Question

I have attached a Jtable code.

I like to remove the "oneCount, twoCount..." because overtime there will get unmaintainable as the grid size increases. I would like to keep a 2D Array of boolean values to indicate whether a cell should be highlighted or not. A mouse pressed on the cell would toggle the value. The renderer would check the value do the the highlighting.

In my renderer I want to keep a 2D Array to represent the state of each cell. I have a MouseListener and I the row and column of the cell. I want to toggle the state of the cell in the renderer and invoke repaint() on the table.

I initialized the 2D boolean array and it should be false by default. When I assign it to true I get the exception "java.lang.ArrayIndexOutOfBounds Exception"

boolean cells[][] = new boolean[row][column]; cells[row][column] = true;

How should I add a 2D boolean array to change the state of each cell?

https://code.sololearn.com/cQ1cVEjne87q/?ref=app

Answer 1

Noting you had ArrayIndexOutOfBounds exception and the snippet in post Description, I think you need to recall that arrays' valid bounds are from 0 up to (not including) the dimension.

So for that 2D array named <cells> which has <row> rows and <column> columns; valid row indices are from 0 ~ <row> - 1, and valid column indices are from 0 ~ <column> - 1.

Now look at it again ...

cells[ row ][ column ] = true;

That is the line that raised the exception cause you try to access an element with invalid index.

Answer 2

In which part (line numbers) did you write the portion involving the use of <cells>? I don't immediately see it in the attached code.

You can assign/modify the array's elements as long as the indices used are valid. How the row & column index are generated? by random? or sequentially? this at least, will decide how you approach the goal.

Answer 3

Hi Mirielle, thanks for your reply. My idea of the code is to highlight each cell individually and be able to un-highlight each cell individually.

Answer 4

So how should I call it. Should i use a loop with cells.length

Answer 5

I've edited the code and used the boolean variable isSelected to print whether the cells boolean 2D array changes from false to true but does not change so I can use the boolean on the change color method.

----------

class TableRenderer extends DefaultTableCellRenderer {

@Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) {

boolean cells[][] = new boolean [4][4];

Component c = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);

if(isSelected) {
if(cells[0][0] == false) {
System.out.println("cell 0 0 is " + cells[0][0]);
cells[0][0] = true;
}
else if(cells[0][0] == true) {
System.out.println("cell 0 0 is " + cells[0][0]);
}
}

return c;
}
}