Develop Reference

How to use JButton in Java

I'm trying to create a hangman game using the Swing class and Graphics class for a APCS class I have.
I created a JButton that would take the guess typed in by the user and either add it to the "misses" or fill in all of the corresponding letters in the word. I have a separate txt file where I pick a random word from.
When I run the program, all of the components show up, but the button does not do anything. I have been working on this for a few days and don't know what I am doing wrong. I have only learnt how to use the Swing class recently, so it may be a stupid mistake for all I know. I have put all of the code down below.
public class Hangman extends JFrame {
DrawPanel panel = new DrawPanel();
Graphics g = panel.getGraphics();
JTextField guess;
JTextField outputWord;
JTextField missesString;
boolean play;
JButton button = new JButton();
String output = "";
String word;
int misses = 0;
public Hangman() {
int again = 0;
String[] dictionary = new String[1000];
In words = new In("words.txt");
JFrame app = new JFrame();
app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
app.setVisible(true);
app.setSize(500, 500);
for (int i = 0; i < 1000; i++) {
dictionary[i] = words.readLine();
}
do {
int num = (int) (Math.random() * 1000);
word = dictionary[num].toLowerCase();
String answer = word;
word = "";
for (int i = answer.length(); i > 0; i--) {
word = word + "*";
}
int length = answer.length();
app.setLayout(new BorderLayout());
JLabel letter = new JLabel();
letter.setFont(new Font("Arial", Font.BOLD, 20));
letter.setText("Enter Your guess");
guess = new JTextField(10);
JLabel output = new JLabel();
output.setFont(new Font("Arial", Font.BOLD, 20));
output.setText("The Word is");
outputWord = new JTextField(30);
outputWord.setText(word);
outputWord.setEditable(false);
JLabel misses = new JLabel();
misses.setFont(new Font("Arial", Font.BOLD, 20));
misses.setText("Misses:");
missesString = new JTextField(52);
missesString.setEditable(false);
button = new JButton("Guess");
button.addActionListener(new ButtonListener());
JPanel panels = new JPanel();
panels.setLayout(new BorderLayout());
JPanel panel1 = new JPanel();
panel1.add(letter);
panel1.add(guess);
panel1.add(button);
JPanel panel2 = new JPanel();
panel2.add(output);
panel2.add(outputWord);
JPanel panel3 = new JPanel();
panel3.add(misses);
panel3.add(missesString);
app.add(panel1, BorderLayout.NORTH);
app.add(panel2, BorderLayout.EAST);
app.add(panel3, BorderLayout.SOUTH);
app.add(panels);
app.setVisible(true);
again = JOptionPane.showConfirmDialog(null, "Do you want to play again?");
} while (again == JOptionPane.YES_OPTION);
}
private class ButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (e.getSource() == guess) {
output = "";
}
for (int i = 0; i <= word.length() - 1; i++) {
if (guess.getText().equalsIgnoreCase(word.substring(i, i + 1))) {
output = output.substring(0, i) + guess + output.substring(i + 1, word.length() - 1);
outputWord.setText(output);
} else {
misses++;
missesString.setText(missesString.getText() + guess + " ");
}
}
}
}
}
The components show up perfectly on the screen, it is only the button that is giving me a hard time by not working as expected.

Event Handling Swing components

I'm trying to learn Java bit by bit, recreating an application I completed in Python - a library control software, very basic. I am having problems, though, with Event Handling, primarily because (I think) I went full-blown in to Swing without knowing much about it, but figuring it out as I went.
Here's my code, so far:
public class SEHBV extends JFrame{
public SEHBV(){
super("SEHBV Biblio 2.0");
ImageIcon img = new ImageIcon("books.ico");
setIconImage(img.getImage());
JPanel p_ini, locar, devolver, buscar, administrar;
JLabel l_dia, l_mes, l_ano, loca_cs, loca_cl, loca_prazo, loca_cb, locado_state;
JTextField dia, mes, ano, loca_cs_tf, loca_cl_tf, loca_prazo_tf, loca_cb_tf, devolve_cod;
JTextArea loca_prazo_data, loca_oper_res, mostra_multa;
JButton data, loca_cb_bt, loca_commit, ver_multa;
JList<String> loca_s_res, loca_cb_res, atrasos, locados;
p_ini = new JPanel(new GridBagLayout());
GridBagConstraints i = new GridBagConstraints();
l_dia = new JLabel("Dia: ");
l_mes = new JLabel("Mês: ");
l_ano = new JLabel("Ano: ");
dia = new JTextField(6);
mes = new JTextField(6);
ano = new JTextField(6);
data = new JButton("Afirmar Data");
atrasos = new JList<String>();
atrasos.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
atrasos.setLayoutOrientation(JList.VERTICAL);
atrasos.setVisibleRowCount(10);
JScrollPane scroll_atrasos = new JScrollPane(atrasos);
atrasos.setBackground(Color.WHITE);
atrasos.setBorder(BorderFactory.createEtchedBorder(EtchedBorder.LOWERED));
i.fill = GridBagConstraints.HORIZONTAL;
i.gridx = 0;
i.gridy = 0;
p_ini.add(l_dia, i);
i.gridx = 1;
p_ini.add(dia, i);
i.gridx = 2;
p_ini.add(l_mes, i);
i.gridx = 3;
p_ini.add(mes, i);
i.gridx = 4;
p_ini.add(l_ano, i);
i.gridx = 5;
p_ini.add(ano, i);
i.gridx = 6;
p_ini.add(data, i);
i.gridy = 1;
i.gridx = 0;
i.gridwidth = 7;
p_ini.add(scroll_atrasos, i);
//GUI Locação
locar = new JPanel(new GridBagLayout());
GridBagConstraints l = new GridBagConstraints();
l.gridx = 0;
l.gridy = 0;
JPanel loca_socios = new JPanel(new FlowLayout());
JPanel loca_oper = new JPanel(new GridBagLayout());
GridBagConstraints o = new GridBagConstraints();
JPanel loca_busca = new JPanel(new GridBagLayout());
GridBagConstraints b = new GridBagConstraints();
locar.add(loca_socios, l); //Busca de Sócios na janela de Locação
loca_s_res = new JList<String>();
loca_s_res.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
loca_s_res.setLayoutOrientation(JList.VERTICAL);
loca_s_res.setModel(Runner.nome_socios);
loca_s_res.setVisibleRowCount(25);
JScrollPane scroll_loca_s = new JScrollPane(loca_s_res);
loca_s_res.setBorder(BorderFactory.createEtchedBorder(EtchedBorder.LOWERED));
loca_socios.add(scroll_loca_s);
l.gridx = 1;
locar.add(loca_oper, l); //Locação propriamente dita
o.weighty = 1;
o.weightx = 1;
o.anchor = GridBagConstraints.NORTHWEST;
o.insets = new Insets(1,1,1,1);
loca_cs = new JLabel("Código do Sócio: ");
o.fill = GridBagConstraints.HORIZONTAL;
o.gridx = 0;
o.gridy = 0;
loca_oper.add(loca_cs, o);
loca_cs_tf = new JTextField(5);
loca_cs_tf.setEditable(false);
loca_cs_tf.setBackground(Color.WHITE);
o.fill = GridBagConstraints.BOTH;
o.gridx = 1;
o.gridy = 0;
loca_oper.add(loca_cs_tf, o);
loca_cl = new JLabel("Código do Livro: ");
o.fill = GridBagConstraints.BOTH;
o.gridx = 0;
o.gridy = 1;
loca_oper.add(loca_cl, o);
loca_cl_tf = new JTextField(5);
o.fill = GridBagConstraints.BOTH;
o.gridx = 1;
o.gridy = 1;
loca_oper.add(loca_cl_tf, o);
loca_prazo = new JLabel("Prazo para devolução (em dias): ");
o.fill = GridBagConstraints.BOTH;
o.gridx = 0;
o.gridy = 2;
loca_oper.add(loca_prazo, o);
loca_prazo_tf = new JTextField(5);
o.fill = GridBagConstraints.BOTH;
o.gridx = 1;
o.gridy = 2;
loca_oper.add(loca_prazo_tf, o);
loca_prazo_data = new JTextArea();
loca_prazo_data.setBackground(getForeground());
o.gridx = 0;
o.gridy = 3;
o.gridwidth = 3;
loca_oper.add(loca_prazo_data, o);
loca_commit = new JButton("Realizar Locação");
o.fill = GridBagConstraints.BOTH;
o.gridx = 0;
o.gridy = 4;
o.gridwidth = 3;
loca_oper.add(loca_commit, o);
loca_oper_res = new JTextArea();
loca_oper_res.setBackground(getForeground());
o.gridy = 5;
loca_oper.add(loca_oper_res, o);
l.gridx = 2;
locar.add(loca_busca, l);
loca_cb = new JLabel("Chave de Busca: ");
b.fill = GridBagConstraints.HORIZONTAL;
b.gridx = 0;
b.gridy = 0;
loca_busca.add(loca_cb, b);
loca_cb_tf = new JTextField(20);
b.fill = GridBagConstraints.HORIZONTAL;
b.gridx = 1;
b.gridy = 0;
loca_busca.add(loca_cb_tf, b);
loca_cb_bt = new JButton("Busca Rápida");
b.fill = GridBagConstraints.HORIZONTAL;
b.gridx = 2;
b.gridy = 0;
loca_busca.add(loca_cb_bt, b);
loca_cb_res = new JList<String>();
loca_cb_res.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
loca_cb_res.setLayoutOrientation(JList.VERTICAL);
b.fill = GridBagConstraints.HORIZONTAL;
loca_cb_res.setBorder(BorderFactory.createEtchedBorder(EtchedBorder.LOWERED));
b.gridx = 0;
b.gridy = 1;
b.gridwidth = 3;
b.gridheight = 2;
loca_cb_res.setVisibleRowCount(25);
JScrollPane scroll_loca_cb = new JScrollPane(loca_cb_res);
loca_cb_res.setBorder(BorderFactory.createEtchedBorder(EtchedBorder.LOWERED));
loca_busca.add(scroll_loca_cb, b);
// Other Tabs of the GUI
//GUI Geral
JTabbedPane tp = new JTabbedPane();
tp.addTab("Página inicial (Alt+I)", null, p_ini, "pág. inicial");
tp.addTab("Locação (Alt+L)", locar);
tp.addTab("Devolução (Alt+D)", devolver);
tp.addTab("Busca Avançada (Alt+B)", buscar);
tp.addTab("Administração (Alt+A)", administrar);
tp.setMnemonicAt(0, KeyEvent.VK_I);
tp.setMnemonicAt(1, KeyEvent.VK_L);
tp.setMnemonicAt(2, KeyEvent.VK_D);
tp.setMnemonicAt(3, KeyEvent.VK_B);
tp.setMnemonicAt(4, KeyEvent.VK_A);
add(tp);
}
So, lets say I'm trying to handle the clicking of the loca_commit JButton. I'm trying to create an Event Handler - according to Java tutorials and other StackOverflow questions/answers - but the handler does not identify loca_commit. Right now I'm just trying to get it to work, then I'll use it for calling a method, but if I can't make it create a pop up, well, you get my point.
So, my code for the handler so far is this:
private class LocaHandler implements ActionListener{
public void actionPerformed(ActionEvent event){
String string = "";
if(event.getSource()==loca_commit)
string=String.format("Botão Apertado");
JOptionPane.showMessageDialog(null, string);
}
Can you guys shed a light here?

The core issue is probably one of context, the LocaHandler probably doesn't have any context to SEHBV or the loca_commit button, so you can't reference it (it's out of context).
There are couple of ways you might fix this...
You could...
Pass a reference of loca_commit to the instance of LocaHandler, but unless you intended to make use of LocaHandler to handle multiple actions, it really doesn't make sense, which means...
You could...
Make LocaHandler responsible for only doing one thing, what ever loca_commit needs it to. This leads you into the realm of the Actions API
How ever...
You could...
Make use of the actionCommand property support of JButton and ActionEvent
loca_commit = new JButton("Realizar Locação");
loca_commit.setActionCommand("locaCommit");
//...
private class LocaHandler implements ActionListener{
public void actionPerformed(ActionEvent event){
String string = "";
if("locaCommit".equals(event.getActionCommand()))
string=String.format("Botão Apertado");
JOptionPane.showMessageDialog(null, string);
}
This means that you could use the same instance of LocaHandler to handle multiple commands (by expanding the if statement)
My personal preference is to use the Actions API or anonymous classes, focusing on the handlers to a single responsibility, if done well, it will increase the reusability of the classes

One way of making it work is to attach action listener on button after initializing it. In your case, try the following:
loca_commit = new JButton("Realizar Locação");
//other code
loca_commit.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null, "Hello");
}
});
loca_oper.add(loca_commit, o);
Remember, this is just one way of doing it. There are multiple other ways to achieve the same result.

JButton and GUI freezes after click

When Eclipse compiles this code everything works fine except the GUI freezes after the user clicks the "add" button. The answer is displayed and the work is shown. Can anyone shine some light on this problem and maybe give me some advice for the layout as well?
import Aritmathic.MathEquation;
public class GUI extends JFrame implements ActionListener{
private JTextField field1;
private JTextField field2;
private JButton add, subtract, multiply, divide;
private JLabel lanswer, label1, label2;
private String input1, input2, sanswer;
private int answer = 0;
JPanel contentPanel, answerPanel;
public GUI(){
super("Calculator");
field1 = new JTextField(null, 15);
field2 = new JTextField(null, 15);
add = new JButton("add");
subtract = new JButton("subtract");
multiply = new JButton("multiply");
divide = new JButton("divide");
lanswer = new JLabel("", SwingConstants.CENTER);
label1 = new JLabel("Value 1:");
label2 = new JLabel("Value 2:");
add.addActionListener(this);
Dimension opSize = new Dimension(110, 20);
Dimension inSize = new Dimension(200, 20);
lanswer.setPreferredSize(new Dimension(200,255));
field1.setPreferredSize(inSize);
field2.setPreferredSize(inSize);
add.setPreferredSize(opSize);
subtract.setPreferredSize(opSize);
multiply.setPreferredSize(opSize);
divide.setPreferredSize(opSize);
contentPanel = new JPanel();
contentPanel.setBackground(Color.PINK);
contentPanel.setLayout(new FlowLayout());
answerPanel = new JPanel();
answerPanel.setPreferredSize(new Dimension(230, 260));
answerPanel.setBackground(Color.WHITE);
answerPanel.setLayout(new BoxLayout(answerPanel, BoxLayout.Y_AXIS));
contentPanel.add(answerPanel);
contentPanel.add(label1); contentPanel.add(field1);
contentPanel.add(label2); contentPanel.add(field2);
contentPanel.add(add); contentPanel.add(subtract); contentPanel.add(multiply); contentPanel.add(divide);
this.setContentPane(contentPanel);
}
public void actionPerformed(ActionEvent e) {
JButton src = (JButton)e.getSource();
if(src.equals(add)){
add();
}
}
private void add(){
input1 = field1.getText();
input2 = field2.getText();
MathEquation problem = new MathEquation(input1, input2);
Dimension lineSize = new Dimension(10, 10);
JPanel line1 = new JPanel(); line1.setBackground(Color.WHITE);
JPanel line2 = new JPanel(); line2.setBackground(Color.WHITE);
JPanel line3 = new JPanel(); line3.setBackground(Color.WHITE);
JPanel line4 = new JPanel(); line4.setBackground(Color.WHITE);
JPanel line5 = new JPanel(); line4.setBackground(Color.WHITE);
JLabel[] sumLabels = problem.getSumLabels();
JLabel[] addend1Labels = problem.getAddend1Labels();
JLabel[] addend2Labels = problem.getAddend2Labels();
JLabel[] carriedLabels = problem.getCarriedLabels();
for(int i = 0; i < carriedLabels.length; i++){
line1.add(carriedLabels[i]);
}
for(int i = 0; i < addend1Labels.length; i++){
line2.add(addend1Labels[i]);
}
for(int i = 0; i < addend2Labels.length; i++){
line3.add(addend2Labels[i]);
}
String answerLine = "__";
for(int i = 0; i < sumLabels.length; i++){
answerLine += "__";
}
line4.add(new JLabel(answerLine));
for(int i = 0; i < sumLabels.length; i++){
line5.add(sumLabels[i]);
}
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(line1);
answerPanel.add(line1);
answerPanel.add(line2);
answerPanel.add(line3);
answerPanel.add(line4);
answerPanel.add(line5);
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
this.setContentPane(answerPanel);
}
}

You have to revalidate your JFrame after you change the content pane.
After
this.setContentPane(answerPanel);
add
revalidate();
Java docs about revalidate()
Your add() method should now look like:
private void add(){
input1 = field1.getText();
input2 = field2.getText();
MathEquation problem = new MathEquation(input1, input2);
Dimension lineSize = new Dimension(10, 10);
JPanel line1 = new JPanel(); line1.setBackground(Color.WHITE);
JPanel line2 = new JPanel(); line2.setBackground(Color.WHITE);
JPanel line3 = new JPanel(); line3.setBackground(Color.WHITE);
JPanel line4 = new JPanel(); line4.setBackground(Color.WHITE);
JPanel line5 = new JPanel(); line4.setBackground(Color.WHITE);
JLabel[] sumLabels = problem.getSumLabels();
JLabel[] addend1Labels = problem.getAddend1Labels();
JLabel[] addend2Labels = problem.getAddend2Labels();
JLabel[] carriedLabels = problem.getCarriedLabels();
for(int i = 0; i < carriedLabels.length; i++){
line1.add(carriedLabels[i]);
}
for(int i = 0; i < addend1Labels.length; i++){
line2.add(addend1Labels[i]);
}
for(int i = 0; i < addend2Labels.length; i++){
line3.add(addend2Labels[i]);
}
String answerLine = "__";
for(int i = 0; i < sumLabels.length; i++){
answerLine += "__";
}
line4.add(new JLabel(answerLine));
for(int i = 0; i < sumLabels.length; i++){
line5.add(sumLabels[i]);
}
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(line1);
answerPanel.add(line1);
answerPanel.add(line2);
answerPanel.add(line3);
answerPanel.add(line4);
answerPanel.add(line5);
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
answerPanel.add(new JLabel(" "));
this.setContentPane(answerPanel);
this.revalidate();//
}
When I tested this it works. By works I mean did not freeze and set the content pane to the answerPanel.

Opening a file with JFileChooser, reading it, and setting values

What I'm trying to do with this GUI is having the person browse for a txt file, and then reading it. When the person clicks the "Read File" button, they should be prompted to choose a file, and then it will read the file and set various values. I am having a few problems with this. First, I'm using scanner to try and set the values, though I am not sure that is the best way. Second, I'm not sure if the file is even being read. I can get the browse for file dialogue to open, but then it freezes, and I have to restart eclipse. How can I use JFileChooser to read a file and set values by reading it?
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Display extends JFrame implements ActionListener {
private static final int FRAME_WIDTH = 400;
private static final int FRAME_HEIGHT = 350;
private static final int FRAME_X_ORIGIN = 100;
private static final int FRAME_Y_ORIGIN = 75;
private JFrame mainFrame;
private JCheckBox avgHSCheckBox;
private JCheckBox avgTSCheckBox;
private JCheckBox homeworkSDCheckBox;
private JCheckBox testSDCheckBox;
private JRadioButton firstClass;
private JRadioButton secondClass;
private JRadioButton thirdClass;
private JRadioButton fourthClass;
private JButton readFileButton;
private JButton exitButton;
private JButton statsButton;
private JButton clearButton;
static int numberOfClasses = 3;
static int numberOfAssignments = 6;
static int numberOfStudents;
static int numberOfLabs = 15;
static int totalHomeworkScore = 0;
static int totalTestScore = 0;
static String classYear;
static String semester;
public static void main(String[] args) {
Display frame = new Display();
frame.setVisible(true);
}
public Display() {
setSize(FRAME_WIDTH, FRAME_HEIGHT);
setResizable(false);
setTitle("CSCE155A Course Offering Viewer");
setLocation(FRAME_X_ORIGIN, FRAME_Y_ORIGIN);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLayout(new BorderLayout());
// header
JPanel header = new JPanel();
header.setLayout(new GridLayout(2, 1));
header.setSize(350, 75);
header.setBorder(BorderFactory.createLineBorder(Color.BLACK));
header.add(new JLabel("CSCE155A Course Offering Viewer"));
header.add(new JLabel("First Last"));
add(header, BorderLayout.NORTH);
// select stats
JPanel statsSelect = new JPanel();
statsSelect.setLayout(new GridLayout(5, 1));
statsSelect.setSize(100, 100);
statsSelect.setBorder(BorderFactory.createLineBorder(Color.BLACK));
statsSelect.add(new JLabel("Please Select: "));
avgHSCheckBox = new JCheckBox("View Average Homework Score");
statsSelect.add(avgHSCheckBox);
avgTSCheckBox = new JCheckBox("View Average Test Score");
statsSelect.add(avgTSCheckBox);
homeworkSDCheckBox = new JCheckBox("View SD for Homework Scores");
statsSelect.add(homeworkSDCheckBox);
testSDCheckBox = new JCheckBox("View SD for Test Scores");
statsSelect.add(testSDCheckBox);
add(statsSelect, BorderLayout.WEST);
// Course offerings
JPanel courseOfferings = new JPanel();
courseOfferings.setLayout(new GridLayout(5, 1));
courseOfferings.setSize(100, 100);
courseOfferings.setBorder(BorderFactory.createLineBorder(Color.BLACK));
courseOfferings.add(new JLabel("Please Select: "));
firstClass = new JRadioButton(semester + classYear);
courseOfferings.add(firstClass);
secondClass = new JRadioButton(semester + classYear);
courseOfferings.add(secondClass);
thirdClass = new JRadioButton(semester + classYear);
courseOfferings.add(thirdClass);
fourthClass = new JRadioButton(semester + classYear);
courseOfferings.add(fourthClass);
add(courseOfferings, BorderLayout.EAST);
// statistics
JPanel statistics = new JPanel();
statistics.setLayout(new GridLayout(5, 1));
statistics.setSize(200, 150);
statistics.setBorder(BorderFactory.createLineBorder(Color.BLACK));
statistics.add(new JLabel("Statistics:"));
add(statistics, BorderLayout.CENTER);
// buttons
JPanel buttons = new JPanel();
buttons.setLayout(new FlowLayout());
buttons.setSize(200, 150);
buttons.setBorder(BorderFactory.createLineBorder(Color.BLACK));
readFileButton = new JButton("Read File");
buttons.add(readFileButton);
exitButton = new JButton("Exit");
buttons.add(exitButton);
statsButton = new JButton("Stats");
buttons.add(statsButton);
clearButton = new JButton("Clear");
buttons.add(clearButton);
add(buttons, BorderLayout.SOUTH);
avgHSCheckBox.addActionListener(this);
avgTSCheckBox.addActionListener(this);
homeworkSDCheckBox.addActionListener(this);
testSDCheckBox.addActionListener(this);
firstClass.addActionListener(this);
secondClass.addActionListener(this);
thirdClass.addActionListener(this);
fourthClass.addActionListener(this);
readFileButton.addActionListener(this);
exitButton.addActionListener(this);
statsButton.addActionListener(this);
clearButton.addActionListener(this);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent event) {
Scanner scanner = new Scanner(System.in);
CourseOffering myCourseOffering = new CourseOffering();
ComputeStatistics myComputeStatistics = new ComputeStatistics();
JButton clickedButton = (JButton) event.getSource();
String buttonText = clickedButton.getText();
if (buttonText.equals("Read File")) {
// Create a file chooser
String filename = File.separator;
JFileChooser fc = new JFileChooser(new File(filename));
fc.showOpenDialog(this);
File selFile = fc.getSelectedFile();
numberOfClasses = scanner.nextInt();
for (int i = 0; i < numberOfClasses; i++) {
myCourseOffering.setDescription(scanner.next()); // CSCE
myCourseOffering.setDescription(scanner.next()); // 155A
myCourseOffering.setDescription(scanner.next()); // -
myCourseOffering.setDescription(scanner.next()); // Semester
semester = myCourseOffering.getDescription();
myCourseOffering.setDescription(scanner.next()); // Year
classYear = myCourseOffering.getDescription();
numberOfStudents = scanner.nextInt(); // Number Of Students
myCourseOffering.students = new Student[numberOfStudents];
for (int j = 0; j < numberOfStudents; j++) {
myCourseOffering.students[j] = new Student();
totalTestScore = 0;
totalHomeworkScore = 0;
// Sets first and last name
myCourseOffering.students[j].setFirstName(scanner.next());
myCourseOffering.students[j].setLastName(scanner.next());
// call assignscores array
int[] assignScores = new int[numberOfAssignments];
for (int k = 0; k < numberOfAssignments; k++) {
assignScores[k] = scanner.nextInt();
totalHomeworkScore += assignScores[k];
}
myCourseOffering.students[j]
.setAssignmentScores(assignScores);
int[] labScores = new int[numberOfLabs];
for (int l = 0; l < numberOfLabs; l++) {
labScores[l] = scanner.nextInt();
totalHomeworkScore += labScores[l];
}
myCourseOffering.students[j].setLabScores(labScores);
myCourseOffering.students[j].setMidTerm1(scanner.nextInt());
totalTestScore += myCourseOffering.students[j]
.getMidterm1();
myCourseOffering.students[j].setMidterm2(scanner.nextInt());
totalTestScore += myCourseOffering.students[j]
.getMidterm2();
myCourseOffering.students[j]
.setFinalExam(scanner.nextInt());
totalTestScore += myCourseOffering.students[j]
.getFinalExam();
myCourseOffering.students[j]
.setQuizScore(scanner.nextInt());
totalTestScore += myCourseOffering.students[j]
.getQuizScore();
myCourseOffering.students[j].setAttendanceScore(scanner
.nextInt());
totalHomeworkScore += myCourseOffering.students[j]
.getAttendanceScore();
myCourseOffering.students[j].setPatScore(scanner.nextInt());
totalTestScore += myCourseOffering.students[j]
.getPatScore();
myCourseOffering.students[j].setZyanteScore(scanner
.nextInt());
totalTestScore += myCourseOffering.students[j]
.getZyanteScore();
myCourseOffering.students[j]
.setTotalHomeworkScore(totalHomeworkScore);
myCourseOffering.students[j]
.setTotalTestScore(totalTestScore);
}
}
}
}
}

The scanner you created uses System.in. You need to create a scanner that operates on the file: Scanner scanner = new Scanner(selFile);.
Also, just FYI, that is an atrocious way to do ActionListeners. I know that tons of examples do that, including the ones from Sun/Oracle, but it's just awful. Attach separate listeners to each button so you're not creating one giant listener that's responsible for everything.

Strings not being, correctly, written to JTextField/Area on selection of row in JList

I'm using a vector to store the information displayed in the JList and I want to use the index of the selected index to copy the data of that row into the JTextField and JTextArea. I am having some issues where the selected item isn't be shown in the JTextField/Area but instead showing the data of a previous selected index. Every second index has an issue of showing the wrong data, 2, 4, 6, 8, 10 and then 11. Each of them will only show the right data if you select first when the program has just been executed. The print lines that I have added to the ListSelectionEvent listener shows the correct data of the selected index but it doesn't correctly copy it into the JTextArea/JTextField.
Selected right after the program was executed.
I selected a few other indices then tried to select it again
code:
public class EditFlashcardGui implements ListSelectionListener {
private JFrame frame;
private JPanel listPanel;
private Vector<Vector> flashcardMasterVector = new Vector<Vector>();
private JList list;
private JPanel tablePanel, dataPanel, textFieldPanel;
private JButton submitButton, cancelButton;
private JTextField frontTextField;
private JTextArea reverseTextArea;
private GridBagLayout gridBagLayout;
private GridBagConstraints constraints;
private JLabel frontTextLabel, reverseTextLabel;
Vector<Vector> masterVector = new Vector<Vector>();
public EditFlashcardGui() {
frame = new JFrame("Edit / Delete Flashcards");
frame.setSize(500, 200);
Container con = frame.getContentPane();
con.setLayout(new BorderLayout());
listPanel = new JPanel(new BorderLayout());
Vector<String> columnNames = new Vector<String>();
columnNames.add("id");
columnNames.add("front text");
columnNames.add("reverse text");
list = new JList(populateList());
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.addListSelectionListener(this);
Font font1 = new Font("SansSerif", Font.BOLD, 20);
list.setFont(font1);
tablePanel = new JPanel();
tablePanel.add(list);
JScrollPane scrollPane = new JScrollPane(list);
con.add(scrollPane, BorderLayout.NORTH);
// south panel
gridBagLayout = new GridBagLayout();
constraints = new GridBagConstraints();
textFieldPanel = new JPanel(gridBagLayout);
// cancelButton = new JButton("Cancel");
// dataPanel.add(cancelButton, BorderLayout.SOUTH);
frontTextLabel = new JLabel("Front Text");
constraints.ipadx = 1;
constraints.ipady = 1;
constraints.gridx = 0;
constraints.gridy = 0;
gridBagLayout.setConstraints(frontTextLabel, constraints);
textFieldPanel.add(frontTextLabel);
frontTextField = new JTextField();
frontTextField.setColumns(30);
constraints.ipadx = 1;
constraints.ipady = 1;
constraints.gridx = 0;
constraints.gridy = 1;
gridBagLayout.setConstraints(frontTextField, constraints);
textFieldPanel.add(frontTextField);
reverseTextLabel = new JLabel("Reverse Text");
constraints.ipadx = 1;
constraints.ipady = 1;
constraints.gridx = 0;
constraints.gridy = 2;
gridBagLayout.setConstraints(reverseTextLabel, constraints);
textFieldPanel.add(reverseTextLabel);
reverseTextArea = new JTextArea(3, 30);
constraints.ipadx = 1;
constraints.ipady = 1;
constraints.gridx = 0;
constraints.gridy = 3;
gridBagLayout.setConstraints(reverseTextArea, constraints);
textFieldPanel.add(reverseTextArea);
submitButton = new JButton("Submit");
constraints.ipadx = 1;
constraints.ipady = 1;
constraints.gridx = 0;
constraints.gridy = 4;
gridBagLayout.setConstraints(submitButton, constraints);
textFieldPanel.add(submitButton);
con.add(textFieldPanel, BorderLayout.CENTER);
frame.setResizable(false);
frame.pack();
frame.setVisible(true);
}
public Vector<Vector> populateList() {
//flashcardMasterVector = flashcardDB.getList();
//Vector<String> flashcardVector = new Vector<String>();
Integer temp = 0;
for(int i = 0; i <= 20; i++) {
Vector<String> flashcardVector = new Vector<String>();
flashcardVector.add(temp.toString());
flashcardVector.add(temp.toString());
flashcardVector.add(temp.toString());
masterVector.add(i, flashcardVector);
temp++;
}
return masterVector;
}
public static void main(String[] args) {
EditFlashcardGui gui = new EditFlashcardGui();
}
#Override
public void valueChanged(ListSelectionEvent e) {
if (! e.getValueIsAdjusting())
{
System.out.print("id : " );
System.out.println(masterVector.get(list.getSelectedIndex()).get(0));
System.out.print("front text : ");
System.out.println(masterVector.get(list.getSelectedIndex()).get(1));
frontTextField.setText(masterVector.get(e.getFirstIndex())
.get(1).toString());
System.out.print("reverse text : ");
System.out.println(masterVector.get(list.getSelectedIndex()).get(2));
reverseTextArea.setText(masterVector.get(e.getFirstIndex())
.get(2).toString());
}
}
}

have to read Oracles tutorial about How to Use JList
you can't put Vector<Vector> to the JList directly,
put value and to use XxxListModel only, but in this case have to create crazy workaround for AbstractListModel, use simple array instead
JList is based on one dimensional array have to use Vector<Object (or String or Double...)>
don't complicate simple things put this array to the JTable (to the XxxTableModel), remove all synchronizations columns, remove JTableHeader if required, then output to the GUI looks like as JList
JTable.removeColumn remove only column from view, all data are still presented and stored into XxxTableModel without any changes
then selected (have to test for -1 == none of row is selected) row (have to convertViewToModel in the case that JTable is sorted or filtered) returns all required data from XxxTableModel

Use list.getSelectedIndex() instead of e.getFirstIndex() method.
Code :
frontTextField.setText( masterVector.get(list.getSelectedIndex() ).get(1).toString() );
reverseTextArea.setText(masterVector.get( list.getSelectedIndex()).get(2).toString() );
Clean Code:
public void valueChanged(ListSelectionEvent e) {
if (!e.getValueIsAdjusting()) {
Vector masterVec = masterVector.get( list.getSelectedIndex() );
System.out.print("id : ");
System.out.println(masterVec.get(0));
System.out.print("front text : ");
System.out.println(masterVec.get(1));
System.out.print("reverse text : ");
System.out.println(masterVec.get(2));
frontTextField.setText(masterVec.get(1).toString());
reverseTextArea.setText(masterVec.get(2).toString());;
}
}