I'm fairly new to GUI programming, and I've been trying to replicate an example where I want to have an array of JButtons right next to each other.
I set the vertical and horizontal gaps both to 0 in the grid layout and still there are spaces between the buttons. On Windows this problem doesn't really exist and you can get the buttons right next to each other.
Can someone help me with this please?
buttons = new JButton[3][3];
buttonP = new JPanel(new GridLayout(3,3,0,0));
for(int i = 0; i < 3; ++i){
for(int j = 0; j < 3; ++j){
buttons[i][j] = new JButton();
buttonP.add(buttons[i][j]);
}
}
add(buttonP);
Related
I am trying to create a grid of buttons.
This is my code to create the grid (which works), but if I want to access a single button later on how would I go about doing that?
for(int i = 1; i<= row; i++){
for( int p=1; p<= col; p++){
boardPanel.add(new JButton());
}
}
Many Thanks
A Clements;
From your question title I'm assuming that you want to be able to access these buttons from a 2d array, but in your code the button is not in an array. If you did something like the following:
JButton[][] buttons = new JButton[row][col];
for(int i = 1; i<= row; i++){
for( int p=1; p<= col; p++){
buttons[i][p] = new JButton();
boardPanel.add(buttons[i][p]);
}
}
Then you are maintaining a 2d array that contains references to the buttons in your JPanel. So now you can access the buttons from the array like this:
buttons[i][j];
I want to add 70 labels and 70 checkboxes in an applet I takes lot of code when we write normally . how to add these labels using for loop
You could use a for loop to add Labels to an array. Something like
List<Label> li = new List<Label>();
for(int i = 0; i < 70; i++)
{
li.add(new Label("label " + i));
}
If you don't want to use an array just you could just add the labels directly to your layout.
FlowLayout fl = new FlowLayout(FlowLayout.CENTER, 10, 10);
for(int i = 0; i < 70; i++)
{
fl.add(new Label("label " + i));
}
In my JPanel I am using tablelayout.jar Oracle library (have a look here) and so, generally, I have to do the following:
private double[][] size = {
{30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30},
{30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30}
};
JPanel p = new JPanel();
p.setLayout(new TableLayout(size));
where "30" is the dimension respectively for cos and rows. In this case we wanted square cells. So I can do, for example,:
p.add(new JButton(), "1,4" /*"col,row"*/);
We thought that declaring that "size" matrix like that was not good to do and so we changed the initialization like the following:
size = new double[Constants.GUI_ROWS][Constants.GUI_COLS];
for (int i=0; i<Constants.GUI_COLS-1; i++)
for (int j=0; j<Constants.GUI_ROWS-1; j++)
size[i][j] = 30;
where
Constants.GUI_COLS = 19 ({30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30})
and
Constants.GUI_ROWS = 17 ({30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30,30})
but this does not work. When we try to add something to the JPanel then nothing is shown. It works only if we write the first initialization by hand. Why this?
To achieve the same as you did by hand you can use
double size[][];
size = new double[2][];
size[0]=new double[19];
size[1]=new double[17];
for (int i=0; i<19; i++)
size[0][i] = 30;
for (int i=0; i<17; i++)
size[1][i] = 30;
You got the loop conditions off by one. Should be :
for (int i=0; i<Constants.GUI_COLS; i++)
for (int j=0; j<Constants.GUI_ROWS; j++)
size[i][j] = 30;
Note that if this call
p.setLayout(new TableLayout(size));
comes before this call :
size = new double[Constants.GUI_ROWS][Constants.GUI_COLS];
The old array referred by size will be used by the TableLayout.
I am trying to add JButtons to the specified location on a gridlayout but I am not sure how to do this, right now I have
public void addButtons()
{
myBoard = myController.getMyBoard();
for (int i = 0; i < this.getEntryInt(); i++)
{
for(int j = 0 ; j < this.getEntryInt(); j++)
{
if(myBoard[i][j]==true)
{
buttons[i][j] = new JButton("Q"); // error: The type of the expression must be an array type but it resolved to JButton
}
}
}
}
Is there a way to add buttons to a specific plot in the grid layout?
You can't choose where you put components in a GridLayout. They will be added consecutively.
Try using a GridBagLayout instead.
I'm working through a JPanel exercise in a Java book. I'm tasked with creating a 5x4 grid using GridLayout.
When I loop through the container to add panels and buttons, the first add() throws the OOB exception. What am I doing wrong?
package mineField;
import java.awt.*;
import javax.swing.*;
#SuppressWarnings("serial")
public class MineField extends JFrame {
private final int WIDTH = 250;
private final int HEIGHT = 120;
private final int MAX_ROWS = 5;
private final int MAX_COLUMNS = 4;
public MineField() {
super("Minefield");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container mineFieldGrid = getContentPane();
mineFieldGrid.setLayout(new GridLayout(MAX_ROWS, MAX_COLUMNS));
// loop through arrays, add panels, then add buttons to panels.
for (int i = 0; i < MAX_ROWS; i++) {
JPanel[] rows = new JPanel[i];
mineFieldGrid.add(rows[i], rows[i].getName());
rows[i].setBackground(Color.blue);
for (int j = 0; j < MAX_COLUMNS; j++) {
JButton[] buttons = new JButton[i];
rows[i].add(buttons[j], buttons[j].getName());
}
}
mineFieldGrid.setSize(WIDTH, HEIGHT);
mineFieldGrid.setVisible(true);
}
public int setRandomBomb(Container con)
{
int bombID;
bombID = (int) (Math.random() * con.getComponentCount());
return bombID;
}
/**
* #param args
*/
public static void main(String[] args) {
//int randomBomb;
//JButton bombLocation;
MineField minePanel = new MineField();
//minePanel[randomBomb] = minePanel.setRandomBomb(minePanel);
}
}
I'm sure I'm over-engineering a simple nested for loop. Since I'm new to Java, please be kind. I'm sure I'll return the favor some day.
JPanel[] rows = new JPanel[i];
i is 0 in the first iteration, which isn't what you want. Make that:
JPanel[] rows = new JPanel[MAX_ROWS];
Also, I think you want to take that completely outside the for loop, since you seem to be using its elements, which would be uninitialised...
This is also wrong:
JButton[] buttons = new JButton[i];
i can be 0 when j is 2 for example, in which case there's no such thing as a buttons[j]. Make them all MAX_* and I think you want to take them out of the loop, since I don't see the point in recreating them at every iteration. Also, you need to instantiate the individual array elements as well.
This part doesn't really make sense:
for (int j = 0; j < MAX_COLUMNS; j++) {
JButton[] buttons = new JButton[i];
rows[i].add(buttons[j], buttons[j].getName());
}
You're creating an array of i JButtons, and trying to add the jth to rows, which makes little sense and won't work if j >= i. You probably meant to do:
JButton[] buttons = new JButton[MAX_COLUMNS];
for (int j = 0; j < MAX_COLUMNS; j++) {
rows[i].add(buttons[j], buttons[j].getName());
}
But the array still doesn't contain any buttons, all you did is initialize it. There's really no reason for the array at all; this actually works:
for (int j = 0; j < MAX_COLUMNS; j++) {
JButton button = new JButton("foo");
rows[i].add(button, button.getName());
}
JPanel[] rows = new JPanel[i];
When i is 0, you create an array with 0 elements. You then try to access that array, but it has no elements in it.
The problem is that your button array is of size i, but j can be larger than i. For instance, the first time through, you are making an empty array here:
JButton[] buttons = new JButton[i];
because i is equal to 0. You then attempt to access it at index 0, which doesn't exist (since the array has no size) and you get your exception. Should you instead be doing something like:
JButton[] buttons = new JButton[MAX_COLUMNS];
That way you will have a button for each array location. Also, you will probably need to initialize the individual buttons - i.e. something like this:
for (int k = 0; k < MAX_COLUMNS; k++) {
buttons[k] = new JButton();
}
(disclaimer: code not tested, but pulled out of you-know-where for example purposes only. There could be typos or unseen bugs.)
Good luck.
It looks like you're creating way too many arrays. You're creating your arrays INSIDE the loops, so instead of creating 5 rows, you're creating 5 rows 5 times, or 25 rows.
The other problem is that you aren't actually creating any objects, only the array to hold the objects. For each object in your array, you need another "button[j] = new JButton()" line.