Develop Reference

Change all the buttons color in java

I have 20 Buttons and i want change the color of the all the buttons when i click on a special button, is there any way to do this with function(or without function) and do not using setBackground for 20 times

You can put the buttons in an array
JButton[] array = new JButton[20];
//then add the buttons to the array
Then:
for(JButton button : array){
button.setBackground(/*the color you want*/);
}

You should not do button1, button2, etc.
Instead, make a List<Button> buttons. You'll still have to call add() 20 times on that list, but then you can loop over them all.
for (Button b : buttons) {
b.setBackground(color);
}

actionlistener for multiple jradiobutton

i have a multiple jradiobutton that is inside a for loop and i am trying to put listener on it and this is what i found:
Action listener for multiple radio buttons
Create two dimensional JRadioButton array like
JRadioButton[][] jRadioButtons = new JRadioButton[8][];
ButtonGroup bg = new ButtonGroup();
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(8, 8));
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
JRadioButton btn = new JRadioButton();
btn.addActionListener(listener);
btn.setName("Btn[" + i + "," + j + "]");
bg.add(btn);
panel.add(btn);
// can be used for other operations
jRadioButtons[i][j] = btn;
}
}
Here is single ActionListener for all JRadioButtons
ActionListener listener = new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JRadioButton btn = (JRadioButton) e.getSource();
System.out.println("Selected Button = " + btn.getName());
}
};
i kinda understand it but i still have few clarifications:
what's the purpose of two dimensional jradiobutton? i mean i kinda see that it is to set a name for the jradiobuttons but as far as my understanding goes, it's only for display. yes to confirm that that is the jradiobutton you've selected but i don't get what's the purpose of it in putting actionlistener
is the two dimensional jradiobutton really that necessary?
can i just use the name of jradiobuttons
to do something like this:
if(NameOfJRadioButton.isSelected())
{
//some procedures
}
^(i can't seem to convert that into code :/)
if so, how can i do it? or do you have any other suggestions on how to put listener for multiple jradiobuttons? thank you for any of your suggestions :)

On your first and second point, the reason for the two dimensional array is unknown as it is not your code, but is not necessary at all for the use of JRadioButtons. However it is useful to have all your buttons in some type of array, whether it be an arraylist, or a buttonGroup (swing list for buttons) for checking things with the buttons when an action is called. e.g. on your 3rd point, this array list would allow you to iterate through and check which buttons have been selected and act accordingly.
The purpose for the action listener is for executing an action when the user clicks on a button. The most general use for this is making it so the user is only allowed to select a certain amount of JRadioButtons or to disable them once they have been selected. e.g. at a character selection menu.

Adding buttons into collection SWT

I have a problem with buttons. I found that when i add buttons into ArrayList, I will can manange every added button. But i don't have idea how to use setEnabled after adding it into ArrayList
public ArrayList<Button> buttons = new ArrayList();
buttons.add(newButton)

If you want all of them to setEnabled(true) then iterate through the array list as #DannyDaglas stated.
for(Button button : buttonList)
button.setEnabled(true);
If you want to pick one of them in specific then you can enter the index of the button and setEnabled(true).
int index = 0;
buttonList.get(index).setEnabled(true);
If you are not sure about which index it is and you have objects of the buttons then you can do something like this
int i;
for (i=0;i<buttonList.size();i++){
if(buttonList.get(i).equals(closeButton))
buttonList.get(i).setEnabled(true);
}

Iterate over the array list with:
for(Button button : buttons)
button.setEnabled(true);

How do I get input from buttons I created using a loop?

I'm trying to make a simple calculator in Java using Swing, and I've created my buttons the following way:
//Our number keypad
public static JPanel numbers(){
//our panel to return
JPanel panel = new JPanel();
//Create and add 3x4 grid layout to panel
GridLayout gl = new GridLayout(3, 4);
panel.setLayout(gl);
//For creating and adding buttons to panel
for(int i = 0; i < 10; i++){
//Create a new button where the name is the value of i
String name = "" + i + "";
JButton button = new JButton(name);
//add action listener
button.addActionListener(handler);
//Add button to panel
panel.add(button);
}
return panel;
}
My question is how do I reference each specific button in my event handler? I can't think of a way to do this without having to manually create each button rather than using a loop.
Thanks.

In your listener, call event.getSource(), and that will return the button which has been pressed. Get the text of the button, and you have its number.
Or create a different instance of your handler for every button, and pass the value of the button (i) to the constructor of the handler. This last solution is cleaner, IMO, because it doesn't depend on the text of the button. If you replaced the text by an image, for example, the first technique wouldn't work anymore.

You can distinguish created buttons by adding the following inside handler:
String buttonText = ((JButton) e.getSource()).getText();
if (<text1>.equals(buttonText)){
//do the stuff
} else if (<text2>.equals(buttonText)){
//do the stuff
} else {
//do the stuff
}

Method #1: go through the child components of the parent JPanel (quite tedious, has to be rebuilt every time you modify the contents of that JPanel). Make sure they're JButtons by using an if . . instanceof clause.
Method #2: as you create them in that loop, add them to a List (or even better, a Map). I prefer a Map personally as it lets me customise the key for that specific JComponent
i.e.
HashMap<String, JComponent> buttonList = new HashMap<String, JComponent>();
for(. .) {
buttonList.put("nameForEachButton", button);
}
I recommend generating the button name based off of the loop counter. Either use your existing name value, or just set it to "button" + i;

Declare your buttons using an array.
JButton[] button = new JButton[9]; //outside the for loop
for (int i = 0; i < 10; i++) {
//put your code
button[i] = new JButton(name);
//your code
}

Java set buttons names automatically

I'm new in Java swing, and I have a problem. I made for-loop for creating buttons and now I want automatically give them names or some kind of marks for future recognition (I will need name of clicked button to make it a variable).
How can I give them names in my loop? Thank you.
Here is code of my for-loop:
for (int aa=1; aa<65; aa++)
{
JButton button = new SquareButton("");
gui.add(button);
button.addActionListener((ActionListener) button);
}

I will need name of clicked button to make it a variable).
You don't need a variable to work with the clicked button. Instead you get a reference to the button that was clicked from the ActionListener code:
public void actionPerformed(ActionEvent e)
{
JButton button = (JButton)e.getSource();
// do processing on the clicked button.
}