Develop Reference

Why does this GUI shift after it updates?

I am working on a simple TicTacToe game with java swing and everything works properly, but whenever the GUI updates the layout changes. This happens with the buttons getting bigger when they are pressed and change to display an 'x' or an 'o' or when the entire game stops and displays a new label saying who won. I'm pretty much a beginner when it comes to programs like this, and the code itself is a huge hodgepodge of copy-pastes from programs that I have made with each separate components, so I figure that could be a reason for this issue.
Code below:
import java.awt.GridBagLayout;
import java.awt.Insets;
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.JTextField;
import javax.swing.Timer;
import java.text.DecimalFormat;
public class test extends JFrame {
private JButton [] buttons = new JButton[9];
private char player = 'x';
private JLabel turnLabel = new JLabel("Player turn: ");
private JLabel turn = new JLabel(Character.toString(player).toUpperCase());
private JLabel winnerLabel = new JLabel("");
private JLabel timeLabel = new JLabel("");
private byte centiseconds = 0;
private byte seconds = 0;
private short minutes = 0;
private DecimalFormat timeFormatter;
private Timer timer;
/* Constructor initializes the Frame,
creates GUI components, and adds them
using a GridBagLayout. */
test() {
GridBagConstraints layoutConst; // Used to specify GUI component layout
// Set frame's title
setTitle("TicTacToe");
// Use a GridBagLayout
setLayout(new GridBagLayout());
// Create GridBagConstraints
layoutConst = new GridBagConstraints();
createObjects(layoutConst);
timer.start();
}
public void createObjects(GridBagConstraints layoutConst) {
int i = 0;
for(int r = 0; r <= 2; r++) {
for(int c = 0; c <= 2; c++) {
buttons[i] = new JButton();
buttons[i].setText(" ");
layoutConst.gridx = r;
layoutConst.gridy = c;
layoutConst.ipadx = 70;
layoutConst.ipady = 70;
add(buttons[i], layoutConst);
buttons[i].addActionListener(e -> {
layoutConst.insets = new Insets(0, 0, 0, 0);
JButton clickedBtn = (JButton) e.getSource();
clickedBtn.setText(String.valueOf(player));
clickedBtn.setEnabled(false);
if (player == 'x')
player = 'o';
else
player = 'x';
turn.setText(Character.toString(player).toUpperCase());
findWinner();
});
i++;
}
createLabels(layoutConst);
}
}
public void createLabels(GridBagConstraints layoutConst) {
layoutConst.gridx = 5;
layoutConst.gridy = 1;
layoutConst.ipady = 0;
layoutConst.ipadx = 0;
layoutConst.insets = new Insets(10, 10, 10, 10);
add(turnLabel, layoutConst);
layoutConst.gridx = 6;
layoutConst.gridy = 1;
layoutConst.gridwidth = 1;
layoutConst.insets = new Insets(0, 0, 0, 0);
add(turn, layoutConst);
layoutConst.gridx = 6;
layoutConst.gridy = 2;
layoutConst.gridwidth = 1;
layoutConst.insets = new Insets(0, 0, 0, 0);
add(winnerLabel, layoutConst);
layoutConst.gridx = 7;
layoutConst.gridy = 0;
layoutConst.insets = new Insets(0, 0, 0, 0);
add(timeLabel, layoutConst);
timeFormatter = new DecimalFormat("00");
timer = new Timer(10, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (centiseconds >= 0 && centiseconds != 100) {
centiseconds++;
}
else if(centiseconds == 100) {
seconds++;
centiseconds = 0;
}
else if(seconds == 60 && centiseconds == 100) {
minutes++;
seconds = 0;
centiseconds = 0;
}
timeLabel.setText(timeFormatter.format(minutes) + ":"
+ timeFormatter.format(seconds) + "."
+ timeFormatter.format(centiseconds));
}
});
timeLabel.setText(timeFormatter.format(minutes) + ":"
+ timeFormatter.format(seconds) + "."
+ timeFormatter.format(centiseconds));
}
public void findWinner() {
if (checkForWinner()) {
if (player == 'x') {
player = 'o';
}
else {
player = 'x';
}
winnerLabel.setText("Player " + Character.toString(player) + " wins!");
timer.stop();
}
else if (checkIfMatchDraw()) {
winnerLabel.setText("It's a draw!");
timer.stop();
}
}
public boolean checkIfMatchDraw() {
boolean gridsFull = true;
for (int i = 0; i < 9; i++) {
if (buttons[i].getText().equals(" ")) {
gridsFull = false;
}
}
return gridsFull;
}
public boolean checkForWinner() {
return checkAllRows() || checkAllColumns() || checkTheDiagonals();
}
public boolean checkAllRows() {
int i = 0;
for (int j = 0; j < 3; j++) {
if (buttons[i].getText().equals(buttons[i + 1].getText()) && buttons[i].getText().equals(buttons[i + 2].getText())
&& !buttons[i].getText().equals(" ")) {
return true;
}
i = i + 3;
}
return false;
}
public boolean checkAllColumns() {
int i = 0;
for (int j = 0; j < 3; j++) {
if (buttons[i].getText().equals(buttons[i + 3].getText()) && buttons[i].getText().equals(buttons[i + 6].getText())
&& !buttons[i].getText().equals(" ")) {
return true;
}
i++;
}
return false;
}
public boolean checkTheDiagonals() {
if (buttons[0].getText().equals(buttons[4].getText()) && buttons[0].getText().equals(buttons[8].getText())
&& !buttons[0].getText().equals(" "))
return true;
else
return buttons[2].getText().equals(buttons[4].getText()) && buttons[2].getText().equals(buttons[6].getText())
&& !buttons[2].getText().equals(" ");
}
/* Creates a Frameand makes it visible */
public static void main(String[] args) {
// Creates Frame and its components
test myFrame = new test();
// Terminate program when window closes
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Resize window to fit components
myFrame.pack();
// Display window
myFrame.setVisible(true);
}
}

How can I organize my Java code?

The title is not my entire question. I know HOW to organize code, theoretically, but i would like some specific, USEFUL, pointers. Please read on before griping.
I'm a beginner to java and OOP (object oriented programming) and I would really like to learn how to better organize my code! Over the course of a month or two, I made a calculator program with little functions I thought of here and there with a few small jokes built into it. After looking at it a second time I realized that it is extremely poorly formatted and almost incomprehensible.If I may, I would like to ask some more experienced programmers to point me in the right direction on what I should do to fix it (for example, what things can I turn into objects, Where can I compartmentalize, etc).
Please note that this is my FIRST time posting on a forum like this so if i need to clarify something for you to help me, I've done something wrong, I'm asking for too much, please tell me so i can resolve it and i can get help. Please dont just mark this as invalid and file it away to oblivion (as often happens in stackoverflow). Also, before anyone asks, NO this is NOT homework, it is the product of my own crack at teaching myself java (probably why its not working too well).
Here is the source code:
// This is the original Calculator code without objects in a single class. not really efficient...
package randomClasses;
import java.awt.*;
import java.awt.event.*;
import java.text.DecimalFormat;
import javax.swing.*;
#SuppressWarnings("serial")
public class CalcClass
extends JFrame
implements ActionListener {
JPanel[] row = new JPanel[6];
JButton[] button = new JButton[21];
String[] buttonString = {"7", "8", "9", "+", "4", "5", "6", "-", "1", "2", "3", "*", ".", "/", "C", "v", "+/-", "=", "0", "Parabola", "x^y"};
int[] dimW = {300, 45, 100, 90, 180};
int[] dimH = {35, 40};
Dimension displayDimension = new Dimension(dimW[0], dimH[0]);
Dimension regularDimension = new Dimension(dimW[1], dimH[1]);
Dimension rColumnDimension = new Dimension(dimW[2], dimH[1]);
Dimension zeroButDimension = new Dimension(dimW[3], dimH[1]);
Dimension parabolaDimension = new Dimension(dimW[4], dimH[0]);
//formatting variables
int var = 0;
double x = 0;
String stor = "";
boolean initial = true;
//variables for Parabola function
int countEquals_parab = 0;
double Angle = 0;
double Vi = 0;
double Vx = 0;
double Vy = 0;
double T_max = 0;
double Y_displ = 0;
double X_displ = 0;
double h = 0;
double k = 0;
double a_parab = 0;
boolean parabComplete = true;
boolean parabola = false;
DecimalFormat df = new DecimalFormat("#######.#####");
//variables for addressing illegal typing issues
boolean typeNum = true;
boolean typeDot = true;
JFrame frame; //for parabolaInstructions
//original calculator variables
boolean[] function = new boolean[5];
double[] temporary = {0, 0}; //store on screen values
double result = 0; //store result
public JTextArea display = new JTextArea(1, 20);
Font font = new Font("Times new Roman", Font.BOLD, 14);
CalcClass() {
super("CalcClass");
setDesign();
setSize(380, 300);
setResizable(false);
setDefaultCloseOperation(EXIT_ON_CLOSE);
GridLayout grid = new GridLayout(6, 5);
setLayout(grid);
for(int i = 0; i < 5; i++) {
function[i] = false;
}
FlowLayout f1 = new FlowLayout(FlowLayout.CENTER);
FlowLayout f2 = new FlowLayout(FlowLayout.CENTER, 1, 1);
for(int i = 0; i < 6; i++) {
row[i] = new JPanel();
}
row[0].setLayout(f1);
for(int i = 1; i < 6; i++) {
row[i].setLayout(f2);
}
for(int i = 0; i < 21; i++) {
button[i] = new JButton();
button[i].setText(buttonString[i]);
button[i].setFont(font);
button[i].addActionListener(this);
}
display.setFont(font);
display.setEditable(false);
display.setPreferredSize(displayDimension);
for(int i = 0; i < 14; i++) {
button[i].setPreferredSize(regularDimension);
}
for(int i = 14; i < 18; i++) {
button[i].setPreferredSize(rColumnDimension);
}
button[18].setPreferredSize(zeroButDimension);
button[19].setPreferredSize(parabolaDimension);
button[20].setPreferredSize(rColumnDimension);
row[0].add(display);
add(row[0]);
for(int i = 0; i < 4; i++) {
row[1].add(button[i]);
}
row[1].add(button[14]);
add(row[1]);
for(int i = 4; i < 8; i++) {
row[2].add(button[i]);
}
row[2].add(button[15]);
add(row[2]);
for(int i = 8; i < 12; i++) {
row[3].add(button[i]);
}
row[3].add(button[16]);
add(row[3]);
row[4].add(button[18]);
for(int i = 12; i < 14; i++) {
row[4].add(button[i]);
}
row[4].add(button[17]);
add(row[4]);
row[5].add(button[19]);
row[5].add(button[20]);
add(row[5]);
setVisible(true);
}
public void getSqrt() {
stor = "";
initial = true;
try {
double value = Double.parseDouble(display.getText());
if(value == -100) {
format("John's Girlfriend");
} else {
value = Math.sqrt(Double.parseDouble(display.getText())); //create a value for variable, and use Maths square root to find the value
format(Double.toString(value)); //Sets display to new value
}
} catch(NumberFormatException e) {
}
typeDot = false;
typeNum = false;
}
public void getPosNeg() {
stor = "";
initial = true;
try {
double value = Double.parseDouble(display.getText()); //again creating a variable for current value
if(value != 0) { //if value is not equal to zero
value = (-1) * value; //multiplied by -1 to change the sign
format(Double.toString(value)); //Sets display to new value
} else {
}
} catch(NumberFormatException e) {
}
}
public void getResult() {
temporary[1] = Double.parseDouble(display.getText());
String temp0 = Double.toString(temporary[0]);
String temp1 = Double.toString(temporary[1]);
try {
if(temp0.contains("-")) {
String[] temp00 = temp0.split("-", 2);
temporary[0] = (Double.parseDouble(temp00[1]) * -1);
}
if(temp1.contains("-")) {
String[] temp11 = temp1.split("-", 2);
temporary[1] = (Double.parseDouble(temp11[1]) * -1);
}
} catch(ArrayIndexOutOfBoundsException e) {
}
try {
functions();
clear();
format(Double.toString(result));//display has a result
for(int i = 0; i < 5; i++) {
function[i] = false; //set all functions to false
}
} catch(NumberFormatException e) {
}
typeNum = false;
}
public void functions() {
if(function[2] == true) { //multiplication
result = temporary[0] * temporary[1];
} else if(function[3] == true) { //division
result = temporary[0] / temporary[1];
} else if(function[0] == true) { //addition
result = temporary[0] + temporary[1];
} else if(function[1] == true) { //subtraction;
result = temporary[0] - temporary[1];
} else if(function[4] == true) {
result = Math.pow(temporary[0], temporary[1]);
} else {
result = temporary[1];
}
}
double a_quadratic = 0;
double b = 0;
double c = 0;
double x1 = 0;
double x2 = 0;
double discr = 0;
int countEquals_quadratic = 0;
public void quadraticFormula() {
if(countEquals_parab == 0) {
a_quadratic = Double.parseDouble(display.getText());
clear();
display.setText("b = ");
}
if(countEquals_parab == 1) {
b = Double.parseDouble(display.getText());
display.setText("c = ");
}
if(countEquals_parab == 2) {
c = Double.parseDouble(display.getText());
discr = (Math.pow(b, 2) - 4 * a_quadratic * c); //stores the value of the discriminant
if(discr >= 0) {
x1 = (-b + Math.sqrt(b * b - 4 * a_quadratic * c)) / (2 * a_quadratic);
x2 = (-b - Math.sqrt(b * b - 4 * a_quadratic * c)) / (2 * a_quadratic);
}
}
}
public void parabolaButton() {
double G = 9.81;
if(countEquals_parab == 0) {
Vi = Double.parseDouble(display.getText());
clear();
display.setText("Angle of release: ");
}
if(countEquals_parab == 1) {
Angle = Double.parseDouble(display.getText());
if((Angle > 90.0) || (Angle < 0.0)) {
display.setText("Sorry, not a valid angle");
countEquals_parab = 3;
} else {
Angle = (Math.PI / 180.0) * Angle; //converting degrees into radians
Vx = Vi * Math.cos(Angle); //Calculating x component
Vy = Vi * Math.sin(Angle); //Calculating y component
//Finding time
T_max = Vy / G; //time to max height
//Calculating vertex coordinates
Y_displ = (Vy * Vy / (2 * G));
X_displ = Vx * T_max;
//finding a
a_parab = (-Y_displ) / (X_displ * X_displ);
display.setText("The equation of the parabola is \ny = " + df.format(a_parab) + "(x - " + df
.format(h) + ")^2 + " + df.format(k));
}
}
if(countEquals_parab == 2) {
display.setText("Time to get to max height = " + df.format(T_max));
}
if(countEquals_parab == 3) {
clearFunction();
countEquals_parab = -1;
parabola = false;
parabComplete = true;
}
countEquals_parab++;
}
public void var() {
var++;
if(var > 8) {
var = 1;
}
if(var == 1) {
format("x");
}
}
public final void setDesign() {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
} catch(Exception e) {
}
}
public void format(String get) {
//get stores the incoming values temporarily
//get is transferred to a new value for permanent storage
//print the permanent storage value
//new number is added, stored temporarily in get
//get is added to permanent storage
//print permanent storage value
double spaceFix = 0;
if(initial == true) {
stor = get;
initial = false;
} else if(initial == false) {
stor = stor + get;
}
spaceFix = stor.length() / 4;
int numberOfSpaces = 56 - stor.length() + (int) spaceFix;
String format = String.format("%" + numberOfSpaces + "s", stor);
display.setText(format);
}
#Override
public void actionPerformed(ActionEvent ae) {
if(ae.getSource() == button[0]) {
numberButtons("7");
}
if(ae.getSource() == button[1]) {
numberButtons("8");
}
if(ae.getSource() == button[2]) {
numberButtons("9");
}
if(ae.getSource() == button[3]) {
operatorButtons(0); //add function[0]
}
if(ae.getSource() == button[4]) {
numberButtons("4");
}
if(ae.getSource() == button[5]) {
numberButtons("5");
}
if(ae.getSource() == button[6]) {
numberButtons("6");
}
if(ae.getSource() == button[7]) {
operatorButtons(1); //subtract function[1]
}
if(ae.getSource() == button[8]) {
numberButtons("1");
}
if(ae.getSource() == button[9]) {
numberButtons("2");
}
if(ae.getSource() == button[10]) {
numberButtons("3");
}
if(ae.getSource() == button[11]) {
operatorButtons(2); //multiplication function[2]
}
if(ae.getSource() == button[12]) {
if(typeDot == false) {
} else {
numberButtons(".");
typeDot = false;
}
}
if(ae.getSource() == button[13]) {
operatorButtons(3); //divide function[3]
}
if(ae.getSource() == button[14]) {
clearFunction();
parabola = false;
parabComplete = true;
}
if(ae.getSource() == button[15]) {
getSqrt();
}
if(ae.getSource() == button[16]) {
getPosNeg();
}
if((ae.getSource() == button[17]) && display.getText().equals("")) {
} else if((ae.getSource() == button[17]) && (parabola == false)) {
getResult();
} else if((ae.getSource() == button[17]) && (parabola == true)) {
parabolaButton();
}
if(ae.getSource() == button[18]) {
numberButtons("0");
}
if(ae.getSource() == button[19]) {
clearFunction();
parabolaInstructions();
parabola = true;
parabComplete = false;
display.setText("Initial velocity: ");
}
if(ae.getSource() == button[20]) {
operatorButtons(4);//powerFunction();
}
}
public void parabolaInstructions() {
//Create the dialog.
final JDialog dialog = new JDialog(frame, "How to use the Parabola function");
//Add contents to it. It must have a close button,
//since some L&Fs (notably Java/Metal) don't provide one
//in the window decorations for dialogs.
JLabel label = new JLabel("<html><p align=center>" + "Step 1: Type in the initial velocity and press the \"=\" button<br>" + "Step 2: Type in the angle of Release (make sure that it is between 0 and 90)<br>" + "Step 3: Press the \"=\" button to scroll through the results<br>" + "Step 4: Profit");
label.setHorizontalAlignment(JLabel.CENTER);
Font font = label.getFont();
label.setFont(label.getFont().deriveFont(font.PLAIN, 14.0f));
JButton closeButton = new JButton("Ok");
closeButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
dialog.setVisible(false);
dialog.dispose();
}
});
JPanel closePanel = new JPanel();
closePanel.setLayout(new BoxLayout(closePanel, BoxLayout.LINE_AXIS));
closePanel.add(Box.createHorizontalGlue());
closePanel.add(closeButton);
closePanel.setBorder(BorderFactory.
createEmptyBorder(0, 0, 5, 5));
JPanel contentPane = new JPanel(new BorderLayout());
contentPane.add(label, BorderLayout.CENTER);
contentPane.add(closePanel, BorderLayout.PAGE_END);
contentPane.setOpaque(true);
dialog.setContentPane(contentPane);
//Show it.
dialog.setSize(new Dimension(400, 200));
dialog.setLocationRelativeTo(frame);
dialog.setVisible(true);
}
public void numberButtons(String i) {
if(typeNum == false) {
display.setText("");
format(i);
} else {
format(i);
}
typeNum = true;
}
public void operatorButtons(int funct) {
if(display.getText().equals("")) {
} else {
temporary[0] = Double.parseDouble(display.getText());
function[funct] = true;
clear();
}
}
public void clearFunction() {
clear();
try {
for(int i = 0; i < 5; i++) {
function[i] = false;
}
for(int i = 0; i < 2; i++) {
temporary[i] = 0;
}
} catch(NullPointerException e) {
}
//For parabola()
Vi = 0;
Vx = 0;
Vy = 0;
T_max = 0;
Y_displ = 0;
X_displ = 0;
h = 0;
k = 0;
a_parab = 0;
}
public void clear() {
display.setText("");
stor = "";
typeDot = true;
initial = true;
}
public static void main(String[] arguments) {
CalcClass c = new CalcClass();
}
}
Ok so now you've seen my mess... I sort-of know what I should do and YES I did some research but I feel it would be much easier to learn organization through example or a nice push than it would be from reading articles that tell you ultra-hypothetical or loosely-analogous examples of what objects are. Note: I tried using methods to organize and my class looks much better than what it did (I also made the whole thing an object to be called upon at the bottom which is pretty much useless).

If you use eclipse, try:
Window > Prefferences > Java > Editor > Save Actions
Check "perform the selected actions on save", "Additional Actions" and click "Configure".
Using eclipse's Save Actions can be really useful in real life coding, but you will probably learn some neat java tricks going through the Save Actions wizard.
Java is an Object Oriented language. You need to take advantage of that fact.
Use classes to separate your code into different logical / structural components. Learn how to use OOP. Follow SOLID design and use design patterns.
Another important thing is to know your language. Start by reading basic classes javadocs and relevant sections of the java spec. I would begin with deeply understanding the different types of java (class, interface, enum and inner / nested / anonymous types) and the different modifiers (private, public, protected, static, abstract, final, default).
Some other eclipse's short cuts:
CTRL-A, CTRL-I ("indentation") will fix your code indentation.
CTRL-SHIFT-O ("organize imports") will omit redundant imports.

You might consider taking a look at Code Complete, which deals with the issues that you're concerned with here, and otherwise is just a classic in our field that every serious developer should read.
In general, when you're organizing code you should do so with a few things in mind: readability and atomicity. These two factors apply to code on every level of an application, from variable naming, routines, methods, classes, packages, and so on.
Readability is a simple idea: can a human being read this code and understand it? To gauge the readability of the code all you have to do is read it! Do variable names help the reader understand what something is? Are routines and classes properly formatted and not needlessly complex? Have you removed all code that isn't being used? Is your code written in a logical progression?
Atomicity is the idea that everything should have one purpose. A function or method should (usually) do one thing and one thing only. A class should usually be a logical grouping of related methods and fields serving some type of unique purpose, and NOT a mish-mash of unrelated stuff. A package should also contain a set of related files. Same with a project, and so on.
The main benefit of atomicity is that once you get into more involved applications it's actually much easier to debug and isolate issues in your code because you know where stuff is. For instance: I have a database access error! Good thing I have a package that's specifically defined for my database access objects.
I know when I was just getting started in the field this was something that threw me off too. It might not be until you do a lot of coding within more significant apps that you really start to understand best practices and why people build stuff a certain way.

Thanks to everyone who contributed to my problem, I completely scrapped this garbage and made it 1000 times better. I knew from the beginning it was poorly made and I wanted to fix it, I just didn't know where to start. After reading all the advice that was given, watching a few tutorials and brushing up on some simple java concepts (modifiers, jswing, etc), I ended up making a new one that is in MVC format (Yay, order and efficiency). Now all my new variables are actually meaningful (Thanks #maaartinus for helping me realize that many of my variables were poorly named and made my whole program unnecessarily complicated). Also, I tried to work on SRP (Not 100% sure if I completely did it but with the program organized it will be easy to change things) and I plan on adding units later for good practice (Thank you, #Robert Snyder). This new GUI is ugly but that can always be changed later and since It is now in MVC format the job will be easier.
Here is what I did (not finished and far from perfect but a step in the right direction):
CalcGui.java
package com.Calculator;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class CalcGui extends JFrame {
private static final long serialVersionUID = 1L;
private String[] operatorsList = { "+", "-", "*", "/", "^" };
// Row 1
private JTextField firstNumber = new JTextField(10);
private JComboBox<String> operator = new JComboBox<>(operatorsList);
private JTextField secondNumber = new JTextField(10);
private JButton calculateButton = new JButton("Calculate");
private JTextField calcSolution = new JTextField(20);
// Row 2
private JLabel sqrtSymbol = new JLabel("√");
private JTextField sqrtNumber = new JTextField(10);
private JButton sqrtCalcButton = new JButton("Calculate");
private JTextField sqrtCalcSolution = new JTextField(20);
// Row 3
private JLabel quadraticLabel1 = new JLabel("A = ");
private JTextField quadraticFirstNumber = new JTextField(5);
private JLabel quadraticLabel2 = new JLabel("B = ");
private JTextField quadraticSecondNumber = new JTextField(5);
private JLabel quadraticLabel3 = new JLabel("C = ");
private JTextField quadraticThirdNumber = new JTextField(5);
private JButton quadraticCalcButton = new JButton("Calculate");
private JLabel quadraticTextBefore = new JLabel("x =");
private JTextField firstQuadraticCalcSolution = new JTextField(3);
private JLabel quadraticTextMiddle = new JLabel("and x =");
private JTextField secondQuadraticCalcSolution = new JTextField(3);
CalcGui() {
JPanel calcPanel = new JPanel(new BorderLayout());
FlowLayout Default = new FlowLayout(FlowLayout.LEFT);
JPanel row1 = new JPanel(Default);
JPanel row2 = new JPanel(Default);
JPanel row3 = new JPanel(Default);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(650, 150);
row1.add(firstNumber);
row1.add(operator);
row1.add(secondNumber);
row1.add(calculateButton);
row1.add(calcSolution);
row2.add(sqrtSymbol);
row2.add(sqrtNumber);
row2.add(sqrtCalcButton);
row2.add(sqrtCalcSolution);
row3.add(quadraticLabel1);
row3.add(quadraticFirstNumber);
row3.add(quadraticLabel2);
row3.add(quadraticSecondNumber);
row3.add(quadraticLabel3);
row3.add(quadraticThirdNumber);
row3.add(quadraticCalcButton);
row3.add(quadraticTextBefore);
row3.add(firstQuadraticCalcSolution);
row3.add(quadraticTextMiddle);
row3.add(secondQuadraticCalcSolution);
calcPanel.add(row1, BorderLayout.NORTH);
calcPanel.add(row2, BorderLayout.CENTER);
calcPanel.add(row3, BorderLayout.SOUTH);
this.add(calcPanel);
}
// basic calculations methods
public double getFirstNumber() {
return Double.parseDouble(firstNumber.getText());
}
public String getOperator() {
return (String) operator.getSelectedItem();
}
public double getSecondNumber() {
return Double.parseDouble(secondNumber.getText());
}
public void setCalcSolution(double solution) {
calcSolution.setText(Double.toString(solution));
}
void addCalculateListener(ActionListener listenForCalcButton) {
calculateButton.addActionListener(listenForCalcButton);
}
void displayErrorMessage(String errorMessage) {
JOptionPane.showMessageDialog(this, errorMessage);
}
// Square root function methods
public double getSqrtNumber() {
return Double.parseDouble(sqrtNumber.getText());
}
public void setSqrtCalcSolution(double solution) {
sqrtCalcSolution.setText(Double.toString(solution));
}
void addSqrtCalcListener(ActionListener listenForSqrtCalcButton) {
sqrtCalcButton.addActionListener(listenForSqrtCalcButton);
}
// Quadratic formula Methods
public double getQuadraticFirstNumber() {
return Double.parseDouble(quadraticFirstNumber.getText());
}
public double getQuadraticSecondNumber() {
return Double.parseDouble(quadraticSecondNumber.getText());
}
public double getQuadraticThirdNumber() {
return Double.parseDouble(quadraticThirdNumber.getText());
}
public void setFirstQuadraticCalcSolution(double solution) {
firstQuadraticCalcSolution.setText(Double.toString(solution));
}
public void setSecondQuadraticCalcSolution(double solution) {
secondQuadraticCalcSolution.setText(Double.toString(solution));
}
void addQuadraticCalcListener(ActionListener listenForQuadraticCalcButton) {
quadraticCalcButton.addActionListener(listenForQuadraticCalcButton);
}
}
CalcModel.java
package com.Calculator;
public class CalcModel {
private double calcValue;
public void calculate(double firstNumber, double secondNumber,
String operator) {
if (operator.equals("+")) {
calcValue = firstNumber + secondNumber;
}
if (operator.equals("-")) {
calcValue = firstNumber - secondNumber;
}
if (operator.equals("*")) {
calcValue = firstNumber * secondNumber;
}
if (operator.equals("/")) {
calcValue = firstNumber / secondNumber;
}
if (operator.equals("^")) {
calcValue = Math.pow(firstNumber, secondNumber);
}
}
public double getCalcValue() {
return calcValue;
}
}
SqrtCalcModel.java
package com.Calculator;
public class SqrtCalcModel {
private double sqrtCalcValue;
public void sqrt(double number) {
sqrtCalcValue = Math.sqrt(number);
}
public double getSqrtCalcValue() {
return sqrtCalcValue;
}
}
QuadraticCalcModel.java
package com.Calculator;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
public class QuadraticCalcModel {
private double firstQuadraticCalcValue;
private double secondQuadraticCalcValue;
public void quadraticFormula(double a, double b, double c) {
double discriminant = (b * b) - (4 * a * c);
if (discriminant >= 0) {
firstQuadraticCalcValue = (Math.sqrt((b * b) - (4 * a * c)) + (-b))
/ (2 * a);
secondQuadraticCalcValue = (Math.sqrt((b * b) - (4 * a * c)) - (-b))
/ (2 * a);
}
else {
JFrame parent = new JFrame();
JOptionPane.showMessageDialog(parent,
"This function has no real roots.");
}
}
public double getFirstQuadraticValue() {
return firstQuadraticCalcValue;
}
public double getSecondQuadraticValue() {
return secondQuadraticCalcValue;
}
}
CalculatorControler.java
package com.Calculator;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class CalculatorController {
private CalcGui theGui;
private CalcModel theCalcModel;
private SqrtCalcModel theSqrtCalcModel;
private QuadraticCalcModel theQuadraticCalcModel;
public CalculatorController(CalcGui theGui, CalcModel theCalcModel,
SqrtCalcModel theSqrtCalcModel,
QuadraticCalcModel theQuadraticCalcModel) {
this.theGui = theGui;
this.theCalcModel = theCalcModel;
this.theSqrtCalcModel = theSqrtCalcModel;
this.theQuadraticCalcModel = theQuadraticCalcModel;
this.theGui.addCalculateListener(new CalcListener());
this.theGui.addSqrtCalcListener(new SqrtCalcListener());
this.theGui.addQuadraticCalcListener(new QuadraticCalcListener());
}
class CalcListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
double firstNumber, secondNumber = 0;
String operator;
try {
firstNumber = theGui.getFirstNumber();
operator = theGui.getOperator();
secondNumber = theGui.getSecondNumber();
theCalcModel.calculate(firstNumber, secondNumber, operator);
theGui.setCalcSolution(theCalcModel.getCalcValue());
}
catch (NumberFormatException ex) {
System.out.println(ex);
theGui.displayErrorMessage("You Need to Enter 2 Numbers");
}
}
}
class SqrtCalcListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
double number = 0;
try {
number = theGui.getSqrtNumber();
theSqrtCalcModel.sqrt(number);
theGui.setSqrtCalcSolution(theSqrtCalcModel.getSqrtCalcValue());
}
catch (NumberFormatException ex) {
System.out.println(ex);
theGui.displayErrorMessage("You Need to enter a Number");
}
}
}
class QuadraticCalcListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
double a, b, c = 0;
try {
a = theGui.getQuadraticFirstNumber();
b = theGui.getQuadraticSecondNumber();
c = theGui.getQuadraticThirdNumber();
theQuadraticCalcModel.quadraticFormula(a, b, c);
theGui.setFirstQuadraticCalcSolution(theQuadraticCalcModel
.getFirstQuadraticValue());
theGui.setSecondQuadraticCalcSolution(theQuadraticCalcModel
.getSecondQuadraticValue());
}
catch (NumberFormatException ex) {
System.out.println(ex);
theGui.displayErrorMessage("You need to enter 3 numbers.");
}
}
}
}
MVCCalculator.java
package com.Calculator;
public class MVCCalculator {
public static void main(String[] args) {
CalcGui theGui = new CalcGui();
CalcModel theCalcModel = new CalcModel();
SqrtCalcModel theSqrtCalcModel = new SqrtCalcModel();
QuadraticCalcModel theQuadraticCalcModel = new QuadraticCalcModel();
new CalculatorController(theGui, theCalcModel, theSqrtCalcModel,
theQuadraticCalcModel);
theGui.setVisible(true);
}
}

Java: Moving arrays to different methods in regards to text

I need help tweaking my code. I need to write a program that outputs the count of individual ascii characters in a txt file that the user uploads, but I'm having a lot of problems trying to get the array that I count into the GUI portion of the program that "draws" the data on the screen.
I have the output looking how I want, but I can't figure out how to get the character count up there
I want to put the number of times a character/punction/number is used in a file that the user uploads on a graphic display. For instance, 33 or ! there are 3 instances. Or 65 A there are 4354 instances in the file. However I'm having a large problem with getting the counter to count the characters in the word correctly, and even more trouble getting the stored array of numbers of characters to the GUI (g.draw) section of the program.
Instead of a number, I just get a blank output column.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.FileReader; // both needed
import java.io.BufferedReader;
import java.io.IOException;
public class textreader extends Frame implements ActionListener
{
String dataFilePath = null;
String dataFileName = null;
int[] counter = new int[256];
String command = "";
public static void main(String[] args)
{
Frame frame = new textreader();
frame.setResizable(true);
frame.setSize(1000,850);
frame.setVisible(true);
}
public textreader()
{
setTitle("Text File Processing");
// Menu Creation
MenuBar mn = new MenuBar();
setMenuBar(mn);
// Create "File" and add it
Menu fileMenu = new Menu("File");
mn.add(fileMenu);
// Create Menu Items, Add action Listener, Add to "File" Menu Group
// Open file
MenuItem miOpen = new MenuItem("Open");
miOpen.addActionListener(this);
fileMenu.add(miOpen);
// Process file
MenuItem miProcess = new MenuItem("Process");
miProcess.addActionListener(this);
fileMenu.add(miProcess);
// Exit program
MenuItem miExit = new MenuItem("Exit");
miExit.addActionListener(this);
fileMenu.add(miExit);
// To Terminate
WindowListener d = new WindowAdapter()
{
public void windowClosing(WindowEvent ev)
{
System.exit(0);
}
public void windowActivated(WindowEvent ev)
{
repaint();
}
public void windowStateChanged(WindowEvent ev)
{
repaint();
}
};
ComponentListener k = new ComponentAdapter()
{
public void componentResized(ComponentEvent e)
{
repaint();
}
};
// listener registry
this.addWindowListener(d);
this.addComponentListener(k);
}
public void actionPerformed (ActionEvent ev)
{
// which command was issued?
command = ev.getActionCommand();
// act
if("Open".equals(command))
{
dataFilePath = null;
dataFileName = null;
JFileChooser chooser = new JFileChooser();
chooser.setDialogType(JFileChooser.OPEN_DIALOG );
chooser.setDialogTitle("Open Data File");
int returnVal = chooser.showOpenDialog(null);
if( returnVal == JFileChooser.APPROVE_OPTION)
{
dataFilePath = chooser.getSelectedFile().getPath();
dataFileName = chooser.getSelectedFile().getName();
}
repaint();
}
else
if("Process".equals(command))
{
try
{
// Initialize
int[] aCount = new int[256];
// "Instantiate" streams
BufferedReader inputStream = new BufferedReader(new FileReader(dataFilePath));
// read the file line by line and count the characters read
String line = null;
char c = 0;
int lineLength = 0;
int charValue = 0;
while ((line = inputStream.readLine()) != null)
{
// ********* process line
for (int i = 0; i < line.length(); i++)
{
char ch = line.charAt(i);
if (ch >= 0 && ch <= 255)
{
counter[(int)ch]++;
}
else
{ // silently ignore non-ASCII characters
}
// count newline at the end
counter['\n']++;
}
}
}
catch(IOException ioe)
{
System.out.print("You want to run that by me again?");
}
repaint();
}
else
if("Exit".equals(command))
{
System.exit(0);
}
}
//********************************************************
//called by repaint() to redraw the screen
//********************************************************
public void paint(Graphics g)
{
if("Open".equals(command))
{
// Acknowledge that file was opened
if (dataFileName != null)
{
g.drawString("File -- "+dataFileName+" -- was successfully opened", 400, 400);
}
else
{
g.drawString("NO File is Open", 400, 400);
}
return;
}
else
if("Process".equals(command))
{
for(int i = 0; i < 256; i++)
{
int x = 100;
int y = 100;
g.drawString("Int", x, y);
g.drawString("Char", x+50, y);
g.drawString("Count", x+100, y);
g.drawLine(100, y+15, x+120, y+15);
y = y + 30;
int line = 0;
for(int j = 0; j < 256; j++)
{
line++;
g.drawString(Integer.toString(j), x, y);
g.drawString(Character.toString((char)j), x + 50, y);
// Converts the # to a char, then to a String
// This part of the code adds a new column when the flag reaches 43
if(line == 45)
{
x = x + 150;
y = 100;
g.drawString("Int", x, y);
g.drawString("Char", x+50, y);
g.drawString("Count", x+100, y);
g.drawLine(100, y+15, x+120, y+15);
y = y + 15;
line = 0;
}
y = y+15;
}
}
return;
}
}
}

just add this to your code:
g.drawString(Integer.toString(counter[j]), x + 120, y);
right here (int the paint method):
g.drawString(Integer.toString(j), x, y);
g.drawString(Character.toString((char)j), x + 50, y);
g.drawString(Integer.toString(counter[j]), x + 120, y);

Java hangman game with gui, problems with incrementing/decrementing numbers

The following part of the code doesn't work, as the won/lost count keeps incrementing by more than 1 for each word, and sometimes I get a nullpointerexception with the string length. Moreover, although the player is supposed to get 7 tries(int no), sometimes he gets more, sometimes less. The Strings are taken from a text file "Hangeng.txt". The whole game is inside a keyboard keytyped listener that is inside a button listener. Any tips on how the layout of the game should generally be arranged so as to avoid errors are welcome, as I am only beginning to work with swing and gui stuff.
public class test{
static int won = 0;
static int lost = 0;
static String key = "";
static String word = null;
static int no = 0;
static StringBuffer toguess;
public static void main(String[] args) throws IOException{
JFrame frame = new JFrame();
frame.setLayout(new GridLayout(3,1));
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
JPanel panel3 = new JPanel();
JButton button = new JButton();
JLabel label = new JLabel();
JLabel label2 = new JLabel();
panel1.add(label);
panel2.add(button);
panel3.add(label2);
frame.setSize(800,600);
frame.add(panel1);
frame.add(panel2);
frame.add(panel3);
frame.setVisible(true);
//the button that starts the game or gets a new word
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
frame.requestFocus();
no = 0;
label2.setText("won " + won + ", lost " + lost);
button.setText("Next");
//get random word from file
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(
"hangeng.txt"));
} catch (FileNotFoundException e1) {
e1.printStackTrace();
}
int lineno = (int) (Math.random() * 100);
for (int i = 0; i < lineno; i++) {
try {
reader.readLine();
} catch (IOException e1) {
e1.printStackTrace();
}
}
try {
word = reader.readLine().replace(" ", "");
} catch (IOException e1) {
e1.printStackTrace();
}
String missing = "";
for (int u = 0; u < (word.length() - 2); u++) {
missing = missing + "*";
}
final String guess = word.charAt(0) + missing
+ word.charAt((word.length() - 1));
toguess = new StringBuffer(guess);
label.setText(toguess.toString());
final ArrayList<String> tried = new ArrayList<String>();
//keylistener that listens to key clicks by the user
frame.addKeyListener(new KeyListener() {
public void keyPressed(KeyEvent arg0) {
}
public void keyReleased(KeyEvent arg0) {
}
public void keyTyped(KeyEvent arg0) {
key = "" + arg0.getKeyChar();
String guessing = null;
boolean k = false;
if ((no < 6)) {
guessing = key;
System.out.println(guessing);
if (!(tried.contains(guessing))) {
tried.add(guessing);
for (int length = 1; length < (guess
.length() - 1); length++) {
if (guessing.equals(String.valueOf(word.charAt(length)))) {
toguess.replace(length,
(length + 1),
String.valueOf(word.charAt(length)));
k = true;
}
}
if (k == true) {
label.setText(toguess.toString());
} else {
no = no + 1;
}
k = false;
}
label.setText(toguess.toString());
if (toguess.toString().equals(word)) {
label.setText("Correct! The word was " + word);
no = 6;
won = won + 1;
}
}
else if ((no == 6)
&& (!(toguess.toString().equals(word)))) {
label.setText("Sorry, but the word was " + word);
lost = lost + 1;
}
}
});
}
});
}
}

+1 to all comments....
Adding to them:
Do not use KeyListener use a KeyAdapter however as you are using Swing and not AWT you should use KeyBindings for Swing see here for example.
Dont forget to create and manipulate Swing components on Event Dispatch Thread via SwingUtiltities.invokeLater(..) block see here for more.
Check class naming schemes they shuld start with capital letter, i.e test should be Test and every new word after that should be capitalized.
Do not call setSize on JFrame rather use appropriate LayoutManager and/or override getPreferredSize() of JPanel and return a size which fits its content and call pack() on JFrame instance after adding all components.
Also SSCCE should be compilable from copy and paste this is not.... i.e variables needed to be changed to final and I dont have a sample of Hangeng.txt so cant test
Lastly use the #Override annotation to ensure you are overriding the correct methods, i.e
#Override
public void actionPerformed(ActionEvent e) {
}

Hangman masking string, unhiding character

I'm writing a hangman application and I'm at the point where I have to write the code to Hide each char in the string (the word being guessed) with "-"... And I've posted a lot of questions on hoe to do it and one of my replies was:Hangman - hide String and then unhide each char if guessed correct
public class HangmanWord {
private static final char HIDECHAR = '_';
private String original;
private String hidden;
public HangmanWord(String original) {
this.original = original;
this.hidden = this.createHidden();
}
private String createHidden() {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < this.original.length; i++) {
sb.append(HIDECHAR);
}
return sb.toString();
}
public boolean check(char input) {
boolean found = false;
for (int i = 0; i < this.original.length; i++) {
if (this.original[i].equals(input)) {
found = true;
this.hidden[i] = this.original[i];
}
}
return found;
}
//getter and setter
}
public class TestClass() {
public static void main(String[] args) {
String secret = "stackoverflow";
int wrongGuesses = 0;
HangmanWord hngm = new HangmanWord(secret);
System.out.println(hngm.getHidden()); // _____________
if (hngm.check('a')) {
System.out.println(hngm.getHidden()); // __a_________
}
else {
wrongGuesses++;
}
//... and so on...
}
}
I tried to use this code with mine and I had a lot of errors and conclusion it didn't work with my code. In my code i've created an array buttons where if the person clicks on a button I get an message saying if the letter is in the word or not... Now I want to replace this code with where it doesn't give me an message but unhides the char and if there's no char it has to change the image
If possible can anyone explain why it didn't work with my code or can anyone please explain to me what to do...
my button array:
public JButton getButton(final String text){
final JButton button = new JButton(text);
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
if(original.toUpperCase().indexOf(button.getText())!=-1){
JOptionPane.showMessageDialog(null, "Your word does contain " + text );
}
else{
JOptionPane.showMessageDialog(null, "There is no " + text );
error++;
if(error >= 0) imageName = "hangman1.jpg";
if(error >= 1) imageName = "hangman2.jpg";
if(error >= 2) imageName = "hangman3.jpg";
if(error >= 3) imageName = "hangman4.jpg";
if(error >= 4) imageName = "hangman5.jpg";
if(error >= 5) imageName = "hangman6.jpg";
if(error >= 7) imageName = "hangman7.jpg";
}
}
});
return button;
}
my full code:
import java.awt.*;
import java.awt.event.*;
import java.util.Arrays;
import javax.swing.*;
import java.io.*;
import java.util.ArrayList;
import java.util.Random;
import java.util.List;
public final class Hangman extends JFrame implements ActionListener{
String original = readWord();
int error;
String imageName;
JButton btnAddWord = new JButton("Add New Word");
JButton btnRestart = new JButton("Restart");
JButton btnHelp = new JButton("Help");
JButton btnExit = new JButton("Exit");
JLabel word = new JLabel(original);
static JPanel panel1 = new JPanel();
static JPanel panel2 = new JPanel();
static JPanel panel3 = new JPanel();
static JPanel panel4 = new JPanel();
public Hangman(){
Container content =getContentPane();
content.setLayout(new GridLayout(0,1));
btnAddWord.addActionListener(this);
btnRestart.addActionListener(this);
btnHelp.addActionListener(this);
btnExit.addActionListener(this);
ImageIcon icon = null;
if(imageName != null){
icon = new ImageIcon(imageName);
}
JLabel image = new JLabel();
image.setIcon(icon);
panel2.add(image);
panel3.add(word);
panel4.add(btnAddWord);
panel4.add(btnRestart);
panel4.add(btnHelp);
panel4.add(btnExit);
for(char i = 'A'; i <= 'Z'; i++){
String buttonText = new Character(i).toString();
JButton button = getButton(buttonText);
panel1.add(button);
}
}
public JButton getButton(final String text){
final JButton button = new JButton(text);
button.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
if(original.toUpperCase().indexOf(button.getText())!=-1){
JOptionPane.showMessageDialog(null, "Your word does contain " + text );
}
else{
JOptionPane.showMessageDialog(null, "There is no " + text );
error++;
if(error >= 0) imageName = "hangman1.jpg";
if(error >= 1) imageName = "hangman2.jpg";
if(error >= 2) imageName = "hangman3.jpg";
if(error >= 3) imageName = "hangman4.jpg";
if(error >= 4) imageName = "hangman5.jpg";
if(error >= 5) imageName = "hangman6.jpg";
if(error >= 7) imageName = "hangman7.jpg";
}
}
});
return button;
}
public String readWord(){
try{
BufferedReader reader = new BufferedReader(new FileReader("Words.txt"));
String line = reader.readLine();
List<String> words = new ArrayList<String>();
while(line != null){
String[] wordsLine = line.split(" ");
boolean addAll = words.addAll(Arrays.asList(wordsLine));
line = reader.readLine();
}
Random rand = new Random(System.currentTimeMillis());
String randomWord = words.get(rand.nextInt(words.size()));
return randomWord;
}catch (Exception e){
return null;
}
}
public void actionPerformed(ActionEvent e){
if(e.getSource() == btnAddWord){
try{
FileWriter fw = new FileWriter("Words.txt", true);
PrintWriter pw = new PrintWriter(fw, true);
String word = JOptionPane.showInputDialog("Please enter a word: ");
pw.println(word);
pw.close();
}
catch(IOException ie){
System.out.println("Error Thrown" + ie.getMessage());
}
}
if(e.getSource() == btnRestart){
}
if(e.getSource() == btnHelp){
String message = "The word to guess is represented by a row of dashes, giving the number of letters and category of the word."
+ "\nIf the guessing player suggests a letter which occurs in the word, the other player writes it in all its correct positions."
+ "\nIf the suggested letter does not occur in the word, the other player draws one element of the hangman diagram as a tally mark."
+ "\n"
+ "\nThe game is over when:"
+ "\nThe guessing player completes the word, or guesses the whole word correctly"
+ "\nThe other player completes the diagram";
JOptionPane.showMessageDialog(null,message, "Help",JOptionPane.INFORMATION_MESSAGE);
}
if(e.getSource() == btnExit){
System.exit(0);
}
}
public static void main (String [] args){
Hangman frame = new Hangman();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 600);
frame.add(panel1, BorderLayout.NORTH);
frame.add(panel2, BorderLayout.CENTER);
frame.add(panel3, BorderLayout.SOUTH);
frame.add(panel4, BorderLayout.SOUTH);
}
}

You've had a good start with your code, but first you need to get the design clear in your mind, before writing code. Let's think about it, in steps:
When the application is launched, you load all the words in the file. So that's a step that is performed only once, and its result (the words in the file) should be saved.
The previous step does not seem to be related to your GUI code, so you may want to do it in your main method, and then pass the results to your GUI class. You can even extract this functionality into a separate class, along with choosing a random word.
Once the GUI is shown, you show a label symbolizing the hidden word. The text of this label should contain as many hidden characters ('-') as the word's characters.
Whenever a correct button is pressed, all matching characters in the word should be shown.
Whenever a wrong button is pressed, an error counter is incremented and an image is shown.
When the whole word is uncovered, character buttons should be disabled.
This leads to a design where you have a separate helper class with a method for reading the words file and another for choosing a random word. Possibly something along the lines of this:
class WordsReader {
public String[] readWords(String filename) {
// ...
}
public String chooseWord(String[] words) {
// ...
}
}
Once a new word is chosen, you should update the label. This is where the HangmanWord class suggested above comes in handy. It stores both the original word and its hidden representation. This allows you to call the check method in the buttons' handler, and update the label's text with the updated hidden representation. The rest of your code should work fine, although it can still be improved.

You could get the chars of the string, and replace the guessed letters with '-' in a new string, and display that (while behind the scenes you still have the full one)
public [static] String hideString(String string, int[] guessedLetterIndices) {
char[] chars = string.toCharArray();
for(int index : guessedLetterIndices)
chars[i] = '-';//Replace this with any letter
for(int i = 0; i < chars.length; i++) {
char c = '-';
for(int index : guessedLetterIndices)
if(index == i)
c = chars[i];
chars[i] = c;
}
return new String(chars);
}
or if you currently have an array of chars that they have chosen, as opposed to indices of characters...
public [static] String hideString(String string, char[] guessedLetters) {
char[] chars = string.toCharArray();
char[] hidden = (string.replaceAll("(.|\n)", "-").toCharArray();
for(int i=0;i<chars.length;i++) {
for(char c : guessedLetters)
if(chars[i] == c) {
hidden[i] = chars[i];
break;
}
]
return new String(chars);
}
That's what I'd do. As far as why yours does not work, could you tell me the errors you're getting? Make sure you're importing StringBuilder and stuff (whatever else they use)