Develop Reference

How to track mouse clicks as input in Java swing

I'm working on a personal project where I'm trying to create Simon game in Java. It is essentially a memory game where the user has to repeat the sequence the computer generates. So, I created a basic CLI version of the game and now I'm looking to give it a GUI. I haven't worked with Java Swing before so I'm having some trouble replicating the same behavior in GUI form.
The structure of the CLI version looked something like this:
public static void main(String[] args) {
GameContext simon = new GameContext();
simon.start();
while (!simon.getRoundEndState()) {
simon.playSequence();
simon.pickColour();
}
}
Here's what the playSequence() method looks like. It essentially generates a number between 0 and 3 and keeps adding one number to the array each round if the player gets the previous one right.
public void playSequence() {
int rand = getRandomNumber(4);
computerSequence.add(rand);
for(int i:computerSequence) {
System.out.println(i);
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
gameContext.setState(gameContext.getHumanPlayingState());
}
pickColour() method that asks the user for the pattern and checks if the pattern matches the one generated by the computer.
public void pickColour() {
boolean roundWon = true;
for(int i=0; i<gameContext.getSequence().size();i++){
Scanner input = new Scanner(System.in);
Integer userInput = input.nextInt();
if(userInput == gameContext.getSequence().get(i)) {
continue;
}
else {
System.out.println("Input mismatched the sequence");
roundWon = false;
break;
}
}
if (roundWon == true) {
score++;
gameContext.setState(gameContext.getComputerPlayingState());
} else {
gameContext.setRoundEndState(true);
System.out.println("Your score is: " + score);
gameContext.setState(gameContext.getInLobbyState());
}
}
Please note that I'm using the state pattern here and hence the change in states. I got the first part working where I need to light up the colors after the computer generates the the sequence. So now, playSequence() looks something like this:
public void playSequence() {
int rand = getRandomNumber(4);
computerSequence.add(rand);
gameContext.setState(gameContext.getHumanPlayingState());
}
And I added a mouse listener to the start button which looks something like this:
btnStart.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent me) {
simon = new GameContext();
simon.start();
while (!simon.getRoundEndState()) {
simon.playSequence();
for(int i : simon.getSequence()) {
lightPanels(i);
Timer timer = new Timer(1000, e -> {
darkenPanels(i);
});
timer.setRepeats(false);
timer.start();
}
simon.pickColour();
}
}
});
I have 4 JPanels that now act as the input buttons. How do I change simon.pickColour() so that instead the asking the user for the correct sequence like it did in the CLI version, it would register the clicks made in the JPanels as the input.

It essentially generates a number between 0 and 3 and keeps adding one number to the array each round if the player gets the previous one right.
and
I have 4 JPanels that now act as the input buttons.
Why have 4 panels. Just have one panel that contains 4 buttons. You would then add an ActionListener to the button (not a MouseListner) to handle the clicking of the button.
The buttons would be created with code like:
for (int i = 1; i <= 4; i++)
{
JButton button = new JButton("" + i);
button.addActionListener(...);
panel.add( button );
}
The ActionListener code would then get the text of the button and add the text to an ArrayList to track the order the the buttons that have been clicked.
A working example of this approach of sharing an ActionListener for all the buttons can be found here: https://stackoverflow.com/a/33739732/131872. Note the "action command" will default from the text that is set on the button.

Java JFrame not working properly in while loop

When I try to run this, I keep getting an empty frame that cannot be closed, and I have to terminate the program from eclipse. I am fairly certain that the problem is a result of the while loop (about 2/3 of the way down the code block), but I haven't been able to figure out a way to fix this
public Draw()
{
super( "Uno");
JMenuBar bar = new JMenuBar(); // create menu bar
JMenu gameMenu = new JMenu( "Play Game" );
JMenu quitMenu = new JMenu( "Quit" ); //Quit Program
bar.add( gameMenu ); // add Add menu to menu bar
bar.add( quitMenu ); // add quit button to menu bar
setJMenuBar( bar ); // set menu bar for this application
window = new JDesktopPane();
add(window);
gameMenu.addMouseListener(
new MouseListener()
{
public void mouseClicked(MouseEvent e)
{
Dimension size = window.getSize();
double height = size.getHeight();
double width = size.getWidth();
JInternalFrame frame = new JInternalFrame("Uno", true, true, true, true );
JFrame input = new JFrame();
input.setTitle(" ");
input.setSize(350, 155);
input.setLayout(new FlowLayout());
input.setLocationRelativeTo(null);
input.setVisible(true);
JLabel label1 = new JLabel("How many total players? (2-10)");
final JTextField text1 = new JTextField(3);
JLabel label2 = new JLabel("How many computer players? *");
final JTextField text2 = new JTextField(3);
JLabel label3 = new JLabel("* Computer players must be <= total number of players");
JButton confirm = new JButton("OK");
label1.setVisible(true);
label2.setVisible(true);
label3.setVisible(true);
text1.setVisible(true);
text2.setVisible(true);
confirm.setVisible(true);
input.add(label1);
input.add(text1);
input.add(label2);
input.add(text2);
input.add(label3);
input.add(confirm);
while(valid == false)
{
confirm.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
String players = text1.getText();
String computers = text2.getText();
int temp1 = Integer.parseInt(players);
System.out.println("Number of players = " + temp1);
int temp2 = Integer.parseInt(computers);
System.out.println("Number of computers = " + temp2);
if (temp1 >= 2 && temp1 <= 10)
if (temp2 <= temp1 && temp2 >= 0)
valid = true;
} //close actionPerformed
}); //close ActionListener
} //close while loop
} //close mouseClicked
} //close mouseListener
} //close Draw
Initially, I was having an issue where it kept infinitely drawing the frame on top of itself because the while loop kept returning false. That issue was solved by removing the components from the while loop, and placing them before it as they are above. Now when I run it, all I get is this: picture
The goal of this program is to make an Uno game, but the first step is to determine the number of players. This is the only way I know how to do this, and this is only the second program I have done with graphics, so I am by no means an expert at Java. I will appreciate any help I can get because I have been stuck for a few days now.

The problem is that you are not giving the event handlers any chance to do their job. Your while loop continually creates event handlers. However, the actionPeformed() method can never be called because the while loop has control of the CPU and the button will not respond to any clicks.
I suggest that you learn a bit more about event handling. You will need to redesign your code in order to get the behavior you wish. Most likely you need to remove the while loop entirely and just create an event handler which will execute code when the button is clicked.
For future reference:
In general, checking equality with a boolean value is unnecessary. The result of == is a bool, but the variable you are checking is already a bool. So use it directly: instead of while (valid == false), you can do while (!valid). If you read the ! as "not", this actually makes a lot of sense.
In this case, the point is moot, since you need to remove the while loop entirely. However, this might be useful information for you some time in the future.

Convert an incrementing/changing String value to existing incremental variable name of JButtons to modify their properties in java

Simplified: How to make String value to call specific existed JButton variable name in java?
I'm trying to make a non-ordinary Tic-Tac-Toe game...
Anyway, what I will post here is not really the whole concept of that. I just want to make it simple: I have 9 square jButtons named (3 by 3) (and maybe allow user to make 4x4, 5x5, 10x10 etc. via settings in future):
[markbox_00_00] / [markbox_00_01] / [markbox_00_02]
[markbox_01_00] / [markbox_01_01] / [markbox_01_02]
[markbox_02_00] / [markbox_02_01] / [markbox_02_02]
[btnSave] / [btnUndoActions]
where the first two digit represent the row and the next two is the column; and a save button (btnSave) and undo button(btnUndoActions).
Each markbox have default spring value of "0", when I click it turns "1"; and when I click "1" it turns "0". When you press undo button it will reset to last save.
Here is some of my simplified line of codes:
private byte markboxColLimit = 3, markboxRowLimit = 3, row, col;
private byte[][] saveNumber = new byte[markboxRowLimit][markboxColLimit];
private String buttonName;
public Astral_TicTacToe() {
initComponents();
/* I want something like this, but using a for loop based on markboxColLimit and
markboxRowLimit as limits */
markbox_00_00.setText("0");
markbox_00_01.setText("0");
markbox_00_02.setText("0");
markbox_01_00.setText("0");
markbox_01_01.setText("0");
markbox_01_02.setText("0");
markbox_02_00.setText("0");
markbox_02_01.setText("0");
markbox_02_02.setText("0");
/* I know the line below is wrong... what I'm trying is to avoid
* repetitiveness by looping and dynamically calling the variable
* name of JButtons, or in other ways...
*/
/* Attempting to make an alternative code from above (trying to make a loop instead) */
for(row = 0; row < markboxRowLimit; row++){
for(col = 0; col < markboxColLimit; col++){
buttonName = "markbox_0" + Byte.toString(row) + "_0" + Byte.toString(col);
buttonName.setText("0");
}
}
}
private void btnUndoActionsActionPerformed(java.awt.event.ActionEvent evt) {
markbox_00_00.setText(Byte.toString(saveNumber[0][0]));
markbox_00_01.setText(Byte.toString(saveNumber[0][1]));
markbox_00_02.setText(Byte.toString(saveNumber[0][2]));
markbox_01_00.setText(Byte.toString(saveNumber[1][0]));
markbox_01_01.setText(Byte.toString(saveNumber[1][1]));
markbox_01_02.setText(Byte.toString(saveNumber[1][2]));
markbox_02_00.setText(Byte.toString(saveNumber[2][0]));
markbox_02_01.setText(Byte.toString(saveNumber[2][1]));
markbox_02_02.setText(Byte.toString(saveNumber[2][2]));
}
private void btnSaveActionPerformed(java.awt.event.ActionEvent evt) {
saveNumber[0][0] = Byte.parseByte(markbox_00_00.getText());
saveNumber[0][1] = Byte.parseByte(markbox_00_01.getText());
saveNumber[0][2] = Byte.parseByte(markbox_00_02.getText());
saveNumber[1][0] = Byte.parseByte(markbox_01_00.getText());
saveNumber[1][1] = Byte.parseByte(markbox_01_01.getText());
saveNumber[1][2] = Byte.parseByte(markbox_01_00.getText());
saveNumber[2][0] = Byte.parseByte(markbox_02_00.getText());
saveNumber[2][1] = Byte.parseByte(markbox_02_01.getText());
saveNumber[2][2] = Byte.parseByte(markbox_02_02.getText());
}
private void markbox_00_00ActionPerformed(java.awt.event.ActionEvent evt) {
if("0".equals(markbox_00_00.getText()))
markbox_00_00.setText("1");
else
markbox_00_00.setText("0");
}
private void markbox_00_01ActionPerformed(java.awt.event.ActionEvent evt) {
if("0".equals(markbox_00_01.getText()))
markbox_00_00.setText("1");
else
markbox_00_00.setText("0");
}
....
private void markbox_02_02ActionPerformed(java.awt.event.ActionEvent evt) {
if("0".equals(markbox_00_00.getText()))
markbox_02_02.setText("1");
else
markbox_02_02.setText("0");
}
In short: how can I make String a specific variable name of JButton for calling/accessing/editing for their properties?
Example:
buttonName = markbox_01_02;
buttonName.setText("2");
is equavalent to markbox_01_02.getText("2");
I really appreciate the help, thank you...
P.S. I use to make JFrame in NetBeans Design (just click and drag the objects in palette window like JPanel, JButton, etc., so I don't type the code manually except making my own logical Method).

You probably need to redo your program and rephrase your question because it's kind of unclear where you're stuck that's why I wrote this answer as a Community Wiki.
The following program creates a GridLayout for the board and add 2 JButtons below it which contain "Save" and "Undo" buttons.
Whenever you press a button it will change it's text to 0 or 1 depending on the previous state of the button, and "Undo" button will undo last clic the same way, if it was 0 it will become 1 and viceversa.
I guess you should read How to write an ActionListener before copy-pasting this example, understand what it says and try to understand how this program works.
The logic to "Save" button is up to you 'cause I'm not sure what you wanna do there and I'm not gonna write all the code for you. This is made only for you to get an idea on how to handle events.
Also, the logic to end the game is left to you for the same reasons as the "Save" button.
I wish I knew how to record my screen in Ubuntu and save as GIF but here's a screenshot on how this program looks like:
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class TicTacToe implements ActionListener {
JFrame frame;
JButton buttons[];
JPanel pane, buttonPane;
boolean pressed[];
JButton save, undo;
int n = -1;
public void actionPerformed(ActionEvent e) {
for (int i = 0; i < buttons.length; i++) {
if(e.getSource() == buttons[i]) {
pressed[i] = !pressed[i];
buttons[i].setText(pressed[i] ? "1" : "0");
n = i;
break;
}
}
}
public TicTacToe () {
frame = new JFrame("Tic Tac Toe Game");
buttons = new JButton[9];
pane = new JPanel(new GridLayout(3, 3));
pressed = new boolean[9];
buttonPane = new JPanel(new FlowLayout());
save = new JButton("Save");
undo = new JButton("Undo");
for (int i = 0; i < buttons.length; i++) {
buttons[i] = new JButton("0");
pressed[i] = false;
}
for (JButton b : buttons) {
b.addActionListener(this);
pane.add(b);
}
undo.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
if (n == -1) {
return;
}
pressed[n] = !pressed[n];
buttons[n].setText(pressed[n] ? "1" : "0");
}
});
buttonPane.add(save);
buttonPane.add(undo);
frame.add(pane, BorderLayout.PAGE_START);
frame.add(buttonPane, BorderLayout.CENTER);
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public static void main (String args[]) {
new TicTacToe();
}
}

JButton doesn't appear until clicked

For this program, the JButton doesn't seem to show up unless you click the area where the JButton should be; the JFrame starts up blank. The moment you click the button, the respective code runs and the button finally shows up.
How do I get the buttons to show up upon starting the program?
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
/*
The Amazing BlackJack Advisory Tool by JoshK,HieuV, and AlvinC.
Prepare to be amazed :O
*/
public class BlckJackUI {
//main class, will contain the JFrame of the program, as well as all the buttons.
public static void main(String args[])
{
//Creating the JFrame
JFrame GUI = new JFrame("Blackjack Advisor");
GUI.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GUI.setSize(1300, 900);
GUI.setContentPane(new JLabel(new ImageIcon("C:\\Users\\Hieu Vo\\Desktop\\Green Background.png")));
GUI.setVisible(true);
// Because each button needs to run through the Math class.
final Math math = new Math();
// The Ace Button:
ImageIcon Ace = new ImageIcon("/Users/computerscience2/Downloads/Ace.jpg");
JButton ace = new JButton(Ace);
ace.setSize(300, 100);
ace.setLocation(100, 100);
ace.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
//Automatically default the the Ace to 11, and if Bust, Ace becomes 1.
if (math.array.playerhandtotal <= 21)
{
math.cardvalue = math.cardvalue + 11;
}
else
{
math.cardvalue = math.cardvalue + 1;
}
math.array.clicktracker++;
math.calcResult();
JOptionPane.showMessageDialog(null,math.array.result);
}
});
GUI.add(ace);
ImageIcon Two = new ImageIcon("/Users/computerscience2/Downloads/2.jpg");
JButton two = new JButton(Two);
two.setSize(300, 100);
two.setLocation(100, 200);
two.addActionListener(new ActionListener ()
{
public void actionPerformed(ActionEvent e)
{
/*
This generally repeats throughout the whole class, and the only
thing different is the changing cardvalue. When a button is pressed,
respective cardvalues are added into the playerhand ArrayList, and
totaled up to form playerhandtotal, which is a major factor in
bringing up the advice.
*/
math.cardvalue = math.cardvalue + 2;
math.array.clicktracker++;
math.calcResult();
JOptionPane.showMessageDialog(null,math.array.result);
}
});
GUI.add(two);
Et cetera, Et cetera... Just a bunch of the same stuff, more buttons coded the same exact way as JButton two, but with different value associated to them.
JButton start = new JButton("Start/Reset");
start.setSize(300, 100);
start.setLocation(500,500);
start.addActionListener(new ActionListener ()
{
public void actionPerformed(ActionEvent e)
{
/*
The start button also acts like a reset button, and the concept is fairly
simple. If we reset all the important values to 0 or "null," then the
program acts as if it was just opened.
*/
Arrays array = new Arrays();
array.playerhand.clear();
array.dealer = 0;
math.array.starttracker++;
math.array.clicktracker = 0;
array.playerhandtotal = 0;
math.cardvalue = 0;
array.result = null;
JOptionPane.showMessageDialog(null,"Please select the card \nthat the dealer is showing :)");
}
});
GUI.add(start);
GUI.setLayout(null);
This is all in the same class, and I understand a layout would be nicer, but perhaps there's a way to fix this issue using what I have now?

The program starts blank because you are calling setVisible before you add components. Call setVisible after you add components (in the end of contructor) and it should work fine.
Also, avoid absolute positioning and call of set|Preferred|Minimum|MaximumSize methods for your components. Learn how to use layout managers.

Write GUI.validate(); after you add all the components to your frame. Any time you add something to a frame you have to validate it like this. Otherwise, you will get the behavior that you have described.

No. The problem is caused by the layout. Before adding anything to a JFrame or a JPanel which you want it to have an absolute position, you have to setLayout(null). Otherwise, you'll have unexpected behaviours all the time. I just figured it out by myself after three hours of experimenting; suddenly, I connected your post with other different subject, and it worked, but this isn't well explained on the Internet yet.

Java basic if/else statement state change

please see my attached code below and then my question at the end.
class events extends JFrame{
private JLabel label;
private JButton button;
public events() {
setLayout(new FlowLayout());
button = new JButton("Click for text");
add(button);
label = new JLabel("");
add(label);
event e = new event();
button.addActionListener(e);
}
public class event implements ActionListener {
public void actionPerformed(ActionEvent e) {
int x = 0;
if (x == 0) {
label.setText("the new label");
System.out
.println("setting x to 0 and label to display a label");
x = 1;
System.out.println(x);
} else {
label.setText("newerer label");
System.out.println("i reached the else segment");
x = 0;
System.out.println(x);
}
}
}
public static void main(String args[]) {
events gui = new events();
gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
gui.setTitle("Events Test");
gui.setSize(300, 100);
gui.setVisible(true);
}
}
Background: I am learning java and attempting to understand a concept. With this program I was attempting to create a small gui with a button that when clicked would assign a JLabel the String value of "the new label." I wanted to use that same button however to change the label to "newerer label" if clicked a second time and back again if clicked a third. I attempted to do this using an If/ Else statement with a variable x to hold essentially a state of 1 or 0. At the end of each portion of the If/Else i change the state of x to either 1 or 0 appropriately. When attempting to run the program in eclipse however, I have run into some kind of error. I assigned a system.out.println to each portion of the If/Else in an attempt to see how the program switches between the two states but it appears that my else statement is never reached.
Questions:
Is an If/Else statement appropriate to perform such a simple 2 state switch?
Is there a more appropriate way to do this? (i know about switch statements but opted for this as it was only a two state project).
What did I do wrong and why is my Else path never achieved when the state should be 1?
Thank you for your responses,
Pano

Your variable "x" must be declared as a class member.
public class event implements ActionListener{
private int x = 0;
public void actionPerformed(ActionEvent e){
if(x == 0){
label.setText("the new label");
System.out.println("setting x to 0 and label to display a label");
x = 1;
System.out.println(x);
}
else {
label.setText("newerer label");
System.out.println("i reached the else segment");
x = 0;
System.out.println(x);
}
}
}

You are initializing x every time the action listener gets called, so x is always 0. Move x somewhere else, possibly declare it as a class member.

Yes, I personally would use an if/else statement here, although if you are likely to add more states a switch statement may be appropriate, but I think given you have more than 1 line of code in the if/else blocks I would keep it as if/else as it has better readability in my experience.
I guess my answer to 1 covers this!
The reason your else block isn't being reached is that your x variable is only in scope (only exists) inside that method. As soon as you leave the method the value is no longer in scope so as far as your code in concerned it no longer exists. The code P Lalonde posted shows the correct way: having the variable as a member variable (object scope). Read more about member variable scope here: http://docs.oracle.com/javase/tutorial/java/javaOO/variables.html

If you are just looking for a switch of state you could actually do something like:
if( label.getText().equals("the new label") ) {
label.setText("newerer label");
} else {
label.setText("the new label");
}