等待并通知等待按钮按下导致 jframe 无法加载

Question

我正在编写一个由我的程序的主要 class 调用的方法（getInfo）。 有一种情况，用户需要从列表（在 JComboBox 中）中 select 来确定该方法返回的内容，所以我希望该方法等到用户做出选择。 我正在尝试使用等待和通知来执行此操作，但是当弹出包含用户选择的 JComboBox 的 jframe 时，它是空的。 我怀疑这是因为调用 wait() 会暂停我的整个程序，所以我怎样才能等待按钮被按下以完成该方法并让它返回一些东西。 这是有问题的 class：

package sm;

import org.jsoup.Jsoup;
//import org.jsoup.*;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JLabel;
import javax.swing.JComboBox;
import javax.swing.JButton;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


public class ScrapingManager {
    
    String courseName;
    String courseType;
    String site;
    Element row;
    Elements allWithName;
    JComboBox<String> options;
    JFrame frame;
    String slots;
    String location;
    public static final Object obj = new Object();

    public ScrapingManager(String name) {
        courseName = name;
        try {
        courseType = name.substring(0, 4);
        } catch(Exception e) {System.out.println("Error: Course code must be at least 4 characters");};
        //getInfo(searchFirstPage());
    }
    
    public String searchFirstPage() {
        Document page;
        String result = "error";
        try {
            page = Jsoup.connect("https://app.stfx.ca/web/Forms/shared/Registrar_website_Timetable.htm").get();
            Element link = page.getElementsContainingOwnText(courseType).first();
            //System.out.println(link.attr("href"));
            result = link.attr("href");
        } catch(Exception e) {/*e.printStackTrace();*/System.out.println("Error: Course code not recognized");}
        return result;
    }
    
    public String[] getInfo() { 
        Document doc;
        slots = "Error";
        location = "Error";
        try {
            doc = Jsoup.connect(searchFirstPage()).get();
            allWithName = doc.getElementsContainingOwnText(courseName).select(":not(:contains('L'))");//it works without select part but shows labs too
            if(allWithName.size() > 1) {
                //give warning that it might be the wrong times
                frame = new JFrame("Warning");
                JPanel panel = new JPanel();
                JLabel warning1 = new JLabel("There are multiple classes with that name,");
                JLabel warning2 = new JLabel("select yours from the list below:");
                String[] array = new String[allWithName.size()];
                for(int i = 0; i < allWithName.size(); i++) {
                    array[i] = allWithName.get(i).parent().child(8).text();
                }
                options = new JComboBox<String>(array);
                JButton ok = new JButton("Select");
                ok.addActionListener(new SubmitListener());
                panel.add(warning1);
                panel.add(warning2);
                panel.add(options);
                panel.add(ok);
                frame.getContentPane().add(panel);
                frame.setSize(400, 300);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
                synchronized(obj) {
                    try {
                    obj.wait();
                    } catch(Exception e) {}
                }
            } else {
                row = doc.getElementsContainingOwnText(courseName).first().parent();
            }
            
            slots = row.child(8).text();
            location = row.child(9).text();
            //System.out.println(slots + " " + location);
        } catch(Exception e) {e.printStackTrace();}
        return new String[] {slots, location};
    }
    
    public class SubmitListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {    
              row = allWithName.get(options.getSelectedIndex());
              frame.dispose();
              synchronized(obj) {
                  obj.notify();
              }
        }    
    }
}

提前致谢！

Answer 1

而不是wait() ，使用JOptionPane.showInputDialog(...) ，就像这里：

import javax.swing.JOptionPane;

public class LanguagesSelector{
    public static void main(String[] args) {
        String[] languages = {"Spanish", "English", "Italian", "Other"};
        Object language = JOptionPane.showInputDialog(null,
                "Choose Language", "language", JOptionPane.PLAIN_MESSAGE,
                null, languages, languages[0]);
        System.out.println("Selected " + language);
    }
}

在JOptionPane class 中，AWT（swing 基于）线程等待用户选择一个选项，因此它应该在您的问题中工作。