如何使用SwingWorker避免冻结GUI

Question

I'm doing a program that creates some Excel files (.xlsx) in an specific folder and I've got a problem with GUI because it's freeze when I call to the method that creates this files.

I want that in the GUI there was a progress bar indeterminate that doesn't stot except there was an exception and a JLabel to show the excel file that it's in creation.

MailPanel class: it's the interface, when I click in a button called "Generate" calls to the method "generateExcel" of the class GenerateExcel()

public class MainPanel extends JPanel {
        .....
        .....
        btnGenerate.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

                jsonFileIssues = ..... ;
                jsonFileProject = ..... ;
                Project project = ..... ;
                key = project.getKey();
                category = project.getCategory();

                String ruta = "C:\\JIRA\\JIRA-Proyectos\\" + category + "\\";   

                .....
                GenerateExcelExterno gee = new GenerateExcelExterno(jsonFileProject, jsonFileIssues, key, ruta, excelFile);
                gee.execute();
                .....
            }
        }
        .....
        .....
    }

---

GenerateExcel class: where it's the importante method to generate the files

I know that I've to add SwingWorker to the GenerateExcel class to unfreeze the GUI, but I can't get it!

The method CREATES the documents, so the doInBackground works, but the progress bar in the panel continues freezed...

public class GenerateExcel extends SwingWorker<Integer, Void> {

    String jsonFileProject, jsonFileIssues, key, ruta, excelFile;

    public GenerateExcel(String jsonFileProject, String jsonFileIssues,
            String key, String ruta, String excelFile) {
        super();
        this.jsonFileProject = jsonFileProject;
        this.jsonFileIssues = jsonFileIssues;
        this.key = key;
        this.ruta = ruta;
        this.excelFile = excelFile;
    }

    public static void generateExcel(String jsonFileProject, String jsonFileIssues, String key, String ruta, String excelFile) {
        .....
        .....
        .....
    }

    @Override
    protected Integer doInBackground() throws Exception {
        // TODO Auto-generated method stub
        generateExcelExterno(jsonFileProject, jsonFileIssues, key, ruta, excelFile);
        return 100; //for example
    }
}

Answer 1

I think that our ability to answer in detail is hampered by the limited information provided, but the gist of your problem is simply that you need to set up your SwingWorker in your control class -- the ActionListener, and then execute it. Inside of the SwingWorker's doInBackground() method should go your long-running code call. Don't make any Swing calls from within doInBackground.

Some useful links:

• JProgressBar without JButton and PropertyChangeListener
• Understanding Java ExecutorService : I like this one most of all.
• Cant get JProgressBar to update from SwingWorker class