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

Question

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);

                    }
                }

            }
        }
    }

Answer 1

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.