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Java Change JButton Color with Method

I've implemented a JFrame with 25 JButton components to represent the available rooms in a hotel. I do know this is not the whole program but how can I create a method in which when pressed the color changes?
The colors for available rooms is green and I would like to change them to red.

This code uses a JToggleButton with different colored icons for standard & selected states. A JCheckBox might also be used.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.net.*;
import java.util.*;
public class RoomReservationToggle {
private JComponent ui = null;
private String reservedPath = "https://i.stack.imgur.com/xj49g.png";
private String freePath = "https://i.stack.imgur.com/zJ8am.png";
RoomReservationToggle() {
try {
initUI();
} catch (MalformedURLException ex) {
ex.printStackTrace();
}
}
public void initUI() throws MalformedURLException {
if (ui != null) {
return;
}
ui = new JPanel(new GridLayout(0, 4, 4, 4));
ui.setBorder(new EmptyBorder(4, 4, 4, 4));
ImageIcon reservedIcon = new ImageIcon(new URL(reservedPath));
ImageIcon freeIcon = new ImageIcon(new URL(freePath));
Random r = new Random();
for (int ii = 1; ii < 17; ii++) {
// a JCheckBox might also be used
JToggleButton tb = new JToggleButton(freeIcon, r.nextBoolean());
tb.setSelectedIcon(reservedIcon);
ui.add(tb);
}
}
public JComponent getUI() {
return ui;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception useDefault) {
}
RoomReservationToggle o = new RoomReservationToggle();
JFrame f = new JFrame(o.getClass().getSimpleName());
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setLocationByPlatform(true);
f.setContentPane(o.getUI());
f.pack();
f.setMinimumSize(f.getSize());
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}

You can use the methods setForeground() and setBackground() to change colours.
Make sure you call these methods from the event thread/queue.
Your configured L&F can ignore these however. Sometimes calling setOpaque(true) might help in those cases.

Update JLabel text

I'm working on a simple GUI. On Button press i want to increase/decrease a variable and update the corresponding JLabel.
class JFrameSetUp
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JFrameSetUp extends JFrame implements ActionListener {
private int RecHeight = 0;
private int RecWidth = 0;
//Here Buttons
JButton HeightIncrease = new JButton("+");
JButton HeightDecrease = new JButton("-");
JLabel height = new JLabel(Integer.toString(RecHeight));
JLabel width = new JLabel(Integer.toString(RecWidth));
GridLayout gridLayout = new GridLayout(2, 4);
public JFrameSetUp(){
}
public void addComponentsToPane(final Container pane){
//Create GridPanel and set Layout
JPanel grid = new JPanel();
grid.setLayout(gridLayout);
//Create buttondrawPanel and set Layout
JPanel buttondraw = new JPanel();
buttondraw.setLayout(new GridLayout(2, 0));
//Adding Components to GridPanel
//Adding Layouts to pane
pane.add(grid, BorderLayout.NORTH);
pane.add(new JSeparator(), BorderLayout.CENTER);
pane.add(buttondraw, BorderLayout.SOUTH);
}
#Override
public void actionPerformed(ActionEvent e) {
//Setting up ActionListener to Buttons
if (e.getSource() == this.HeightDecrease) {
RecHeight -= 1;
height.setText(Integer.toString(RecHeight));
} else if (e.getSource() == this.HeightIncrease) {
RecHeight += 1;
height.setText(Integer.toString(RecHeight));
}
}
}
Class with MainMethod
import javax.swing.JFrame;
public class Program {
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
private static void createAndShowGUI() {
//Create and set up the window.
JFrameSetUp frame = new JFrameSetUp();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set up the content pane.
frame.addComponentsToPane(frame.getContentPane());
//Display the window.
frame.pack();
frame.setVisible(true);
}
}
I'm aware, that's kind a newbish question. I think I'm wrong with my Code Structure. Any help is appreciated.
Thanks in advance.

You never register any ActionListeners to the buttons...
HeightIncrease.addActionListener(this);
HeightDecrease.addActionListener(this);
You also never add the buttons to the GUI
buttondraw.add(HeightIncrease);
buttondraw.add(HeightDecrease);
You also never add the labels to the GUI either...
grid.add(height);
grid.add(width);
I reworked the code, because your example was messing with my mind, hope you don't mind...
It's conceptually the same idea, just done slightly more efficently
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private int recHeight = 0;
private int recWidth = 0;
//Here Buttons
JButton heightIncrease = new JButton("+");
JButton heightDecrease = new JButton("-");
JLabel height = new JLabel(Integer.toString(recHeight));
JLabel width = new JLabel(Integer.toString(recWidth));
GridLayout gridLayout = new GridLayout(2, 4);
public TestPane() {
setLayout(new BorderLayout());
//Create GridPanel and set Layout
JPanel grid = new JPanel();
grid.setLayout(gridLayout);
grid.add(height);
grid.add(width);
//Create buttondrawPanel and set Layout
JPanel buttondraw = new JPanel();
buttondraw.setLayout(new GridLayout(2, 0));
heightIncrease.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
recHeight += 1;
height.setText(Integer.toString(recHeight));
}
});
heightDecrease.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
recHeight -= 1;
height.setText(Integer.toString(recHeight));
}
});
buttondraw.add(heightIncrease);
buttondraw.add(heightDecrease);
//Adding Components to GridPanel
//Adding Layouts to pane
add(grid, BorderLayout.NORTH);
add(new JSeparator(), BorderLayout.CENTER);
add(buttondraw, BorderLayout.SOUTH);
}
}
}
I would encourage you to spend some time having a look at How to Use Buttons, Check Boxes, and Radio Buttons and How to Write an Action Listeners for more details

After changing the value call
frame.repaint();

Good to see you learning Java! A few things I should point out.
Firstly, your variable names are good, but they don't follow the Java naming convention. Even though it seems small, it's just good practice to follow.
Of course, your actual problem; the action listener you've implemented is on the JFrame. (See how you extend JFrame and implement ActionListener?) This ActionListener should be on the button. You'll can do this a few ways.
Method 1: By adding it inline with your code
JButton heightButton = new JButton("Increase Height");
heightButton.addActionListener(new ActionListener(){
#Override
public void run(){
//run method here
}
});
Method 2: Create a class which implements ActionListener
class ButtonListener implements ActionListener{
#Override
public void run(){
//actionListener code here
}
}
And then instantiate an object of this type and add it directly to your code.
ActionListner buttonListener = new ButtonListener(); //or ButtonListener buttonListener = new ButtonListener();
JButton heightButton = new JButton("Increase Height");
heightButton.addActionListener(buttonListener);
Of course, as in MadProgrammers answer, don't forget to add the labels and such to your JFrame or JPanel. Good luck learning Java!

I bet that your program just shows nothing, isn't it? That's because in addComponentsToPane method, you didn't add any component but empty JPanels. After the comment //Adding Components to GridPanel, you should:
buttondraw.add(HeightIncrease);
buttondraw.add(HeightDecrease);
grid.add(height);
grid.add(width);
Then, to listen to button event, you should also add :
HeightIncrease.addActionListener(this);
HeightDecrease.addActionListener(this);
"this" is because your frame JFrameSetUp implements ActionListener, so when either bootton is clicked the method actionPerformed is invoked.
As JLabel.setText method will repaint itself and consequently its component hierarchi is repainted as well, you haven't to do anything othr.

Responsive JFrame without Layout Manager

I am trying to do have two button in JFrame, and I call the setBounds method of them for setting the positions and size of them and also I passed null to setLayout1 because I want to usesetBounds` method of component.
Now I want to do something with my code that whenever I resize the frame buttons decoration will change in a suitable form like below pictures:
I know it is possible to use create an object from JPanel class and add buttons to it and at the end add created panel object to frame, but I am not allowed to it right now because of some reason (specified by professor).
Is there any way or do you have any suggestion?
My code is like this:
public class Responsive
{
public static void main(String[] args)
{
JFrame jFrame = new JFrame("Responsive JFrame");
jFrame.setLayout(null);
jFrame.setBounds(0,0,400,300);
JButton jButton1 = new JButton("button 1");
JButton jButton2 = new JButton("button 2");
jButton1.setBounds(50,50,100,100);
jButton2.setBounds(150,50,100,100);
jFrame.add(jButton1);
jFrame.add(jButton2);
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setVisible(true);
}
}

A FlowLayout with no horizontal spacing, some vertical spacing and large borders could achieve that easily. A null layout manager is never the answer to a 'responsive' robust GUI.
import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class ResponsiveGUI {
private JComponent ui = null;
ResponsiveGUI() {
initUI();
}
public void initUI() {
if (ui!=null) return;
ui = new JPanel(new FlowLayout(FlowLayout.CENTER, 0, 8));
ui.setBorder(new EmptyBorder(10,40,10,40));
for (int i=1; i<3; i++) {
ui.add(getBigButton(i));
}
}
public JComponent getUI() {
return ui;
}
private final JButton getBigButton(int number) {
JButton b = new JButton("Button " + number);
int pad = 20;
b.setMargin(new Insets(pad, pad, pad, pad));
return b;
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception useDefault) {
}
ResponsiveGUI o = new ResponsiveGUI();
JFrame f = new JFrame("Responsive GUI");
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setLocationByPlatform(true);
f.setContentPane(o.getUI());
f.pack();
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}

You could try to use:
jFrame.addComponentListener(new ComponentListener() {
// this method invokes each time you resize the frame
public void componentResized(ComponentEvent e) {
// your calculations on buttons
}
});

How do I "activate" a button on the GUI?

By now, I already know my code is flawed. I just want to know why it's flawed. I want to activate the "webButton" so that when it gets clicked, it prints a message on the console that reads "This opens Mozilla Firefox."
package smartphone;
import java.awt.*;
import java.awt.event.ActionEvent;
import javax.swing.*;
import java.util.Scanner;
public class Smartphone implements ActionListener {
public static void main(String[] args) {
{
{
JFrame container = new JFrame();
container.setLayout(new BorderLayout());
Scanner daniel = new Scanner(System.in);
JButton webButton = new JButton(new ImageIcon("Firefox.png"));
JButton phoButton = new JButton(new ImageIcon("Facebook.png"));
JButton texButton = new JButton(new ImageIcon("Phone.png"));
JButton setButton = new JButton(new ImageIcon("Settings.png"));
JButton smsButton = new JButton(new ImageIcon("sms.png"));
container.setTitle("Smartphone Interface!");
container.setSize(240,340);
container.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
container.add(setButton, BorderLayout.CENTER);
container.add(webButton, BorderLayout.SOUTH);
container.add(texButton, BorderLayout.NORTH);
container.add(phoButton, BorderLayout.EAST);
container.add(smsButton, BorderLayout.WEST);
container.setVisible(true);
webButton.addActionListener(instanceofSmartphone);
}
}
}
}

Do this.
webButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
//Execute when button is pressed
}
});
If you want to use the ActionListener interface then, implement it in your Frame class and then replace that instanceOfSmartphone with
webButton.addActionListener(this);
And put this outside the method
public void actionPerformed(ActionEvent e) {
if(e.getSource() == webButton) {
}
}

You need to implement the actionPerformed method. An example follows.
public void actionPerformed(ActionEvent e) {
System.out.println("This method opens Mozilla Firefox.");
}
Additionally, you need to change how you add the action listener to the following.
webButton.addActionListener(this);
There are also a number of other issues. Here is a modified version of your code to get it working but far from perfect or what you will want in the end. I strongly recommend you walk through all of the tutorials in order at the below website. It doesn't get any easier than what they have. Also, if your not already using it, you should try Netbeans or some other IDE. It give you feedback that may help while you are starting out.
https://docs.oracle.com/javase/tutorial/
package smartphone;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import java.util.Scanner;
public class Smartphone extends Frame implements ActionListener {
static JButton webButton = new JButton(new ImageIcon("Firefox.png"));
static JButton phoButton = new JButton(new ImageIcon("Facebook.png"));
static JButton texButton = new JButton(new ImageIcon("Phone.png"));
static JButton setButton = new JButton(new ImageIcon("Settings.png"));
static JButton smsButton = new JButton(new ImageIcon("sms.png"));
Smartphone(){
webButton.addActionListener(this);
}
public static void main(String[] args) {
Smartphone container = new Smartphone();
container.setLayout(new BorderLayout());
Scanner daniel = new Scanner(System.in);
container.setTitle("Smartphone Interface!");
container.setSize(240, 340);
container.add(setButton, BorderLayout.CENTER);
container.add(webButton, BorderLayout.SOUTH);
container.add(texButton, BorderLayout.NORTH);
container.add(phoButton, BorderLayout.EAST);
container.add(smsButton, BorderLayout.WEST);
container.setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("This opens a Firefox Webbrowser.");
}
}

You need to add an ActionListener to the buttons INSIDE of the constructor: buttonName.addActionListener(this);.
Then you need to create the following method:
public void actionPerformed(ActionEvent event) {
Object control = event.getSource();
if (control == buttonName) {
//Run code...
}
}

Change the textfield location of a JSpinner

I'd like to custom a little bit the basic JSpinner of swing java API.
Basically, I want to move the textfield component initially located on the left of the arrow buttons. Instead, the texfield would be lcoated between the two arrows of the spinner, so that there's one arrow on top of the textfield and one arrow below the texfield.
But I don't know how to proceed...
Anyone would have an idea?

You might be able to override the setLayout(LayoutManager) method of JSpinner to use a custom LayoutManager.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SpinnerLayoutTest {
public JComponent makeUI() {
SpinnerNumberModel m = new SpinnerNumberModel(10, 0, 1000, 1);
JSpinner spinner = new JSpinner(m) {
#Override public void setLayout(LayoutManager mgr) {
super.setLayout(new SpinnerLayout());
}
};
JPanel p = new JPanel(new BorderLayout(5,5));
p.add(new JSpinner(m), BorderLayout.NORTH);
p.add(spinner, BorderLayout.SOUTH);
p.setBorder(BorderFactory.createEmptyBorder(16,16,16,16));
return p;
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override public void run() {
createAndShowGUI();
}
});
}
public static void createAndShowGUI() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
f.getContentPane().add(new SpinnerLayoutTest().makeUI());
f.setSize(320, 160);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class SpinnerLayout extends BorderLayout {
#Override public void addLayoutComponent(Component comp, Object constraints) {
if("Editor".equals(constraints)) {
constraints = "Center";
} else if("Next".equals(constraints)) {
constraints = "North";
} else if("Previous".equals(constraints)) {
constraints = "South";
}
super.addLayoutComponent(comp, constraints);
}
}

You could make an JPanel and put a JTextField and the JButtons inside it. That's was soulution, when I had the same problem.
EDIT:
Arrowbuttons can you create with:
new javax.swing.plaf.basic.BasicArrowButton(SwingConstants.NORTH);
Where SwingConstants.NORTH says that the arrow in the button is pointing upwards