我不能让我的程序等到 GUI 完成收集请求的信息 (Java)

Question

我对 Java 还是很陌生，在我最终提出这个问题之前，我搜索并搜索了 SO，但我似乎并没有完全理解它。 如您所见，我有一个创建 GUI 的类，请求一些输入并将该输入存储在可返回的 String[] 中。

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class InputConsole {
final static boolean shouldFill = true;
final static boolean shouldWeightX = true;
final static boolean RIGHT_TO_LEFT = false;
public static String[] details = new String[3];
public static JButton btn2013;
public static JButton btn2014;
public static JButton btn2015;
public static JButton btn2016;
public static JButton btnGo;
public static JTextField textField2;
public static JTextField textField4;

public static void addComponentsToPane(Container pane) {
    if (RIGHT_TO_LEFT) {
        pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
    }

    pane.setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();
    if (shouldFill) {
        c.fill = GridBagConstraints.HORIZONTAL;
    }

    btn2013 = new JButton("ZMR 2013");
    btn2013.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            details[2] = "2013";
            btn2014.setEnabled(false);
            btn2015.setEnabled(false);
            btn2016.setEnabled(false);
            textField2.requestFocusInWindow();

        }
    });
    if (shouldWeightX) {
        c.weightx = 0.0;
    }
    c.fill = GridBagConstraints.HORIZONTAL;
    c.insets = new Insets(10, 0, 0, 0);
    c.gridx = 0;
    c.gridy = 0;
    pane.add(btn2013, c);

    btn2014 = new JButton("ZMR 2014");
    btn2014.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            details[2] = "2014";
            btn2013.setEnabled(false);
            btn2015.setEnabled(false);
            btn2016.setEnabled(false);
            textField2.requestFocusInWindow();
        }
    });
    c.fill = GridBagConstraints.HORIZONTAL;
    c.insets = new Insets(10, 10, 0, 0);
    c.weightx = 0.0;
    c.gridx = 1;
    c.gridy = 0;
    pane.add(btn2014, c);

    btn2015 = new JButton("ZMR 2015");
    btn2015.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            details[2] = "2015";
            btn2013.setEnabled(false);
            btn2014.setEnabled(false);
            btn2016.setEnabled(false);
            textField2.requestFocusInWindow();
        }
    });
    c.fill = GridBagConstraints.HORIZONTAL;
    c.weightx = 0.0;
    c.gridx = 2;
    c.gridy = 0;
    pane.add(btn2015, c);

    btn2016 = new JButton("ZMR 2016");
    btn2016.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            details[2] = "2016";
            btn2013.setEnabled(false);
            btn2014.setEnabled(false);
            btn2015.setEnabled(false);
            textField2.requestFocusInWindow();
        }
    });
    c.fill = GridBagConstraints.HORIZONTAL;
    c.weightx = 0.0;
    c.gridx = 3;
    c.gridy = 0;
    pane.add(btn2016, c);

    JLabel textField1 = new JLabel("What was your Bib number? : ");
    c.fill = GridBagConstraints.HORIZONTAL;
    c.gridx = 0;
    c.gridy = 2;
    c.gridwidth = 2;
    pane.add(textField1, c);

    textField2 = new JTextField(10);
    textField2.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            details[0] = textField2.getText();
            textField4.requestFocusInWindow();

        }

    });

    c.fill = GridBagConstraints.HORIZONTAL;
    c.gridx = 2;
    c.gridy = 2;
    pane.add(textField2, c);

    JLabel textField3 = new JLabel("What is your email address : ");

    c.fill = GridBagConstraints.HORIZONTAL;
    c.gridx = 0;
    c.gridy = 3;
    c.gridwidth = 2;
    pane.add(textField3, c);

    textField4 = new JTextField(15);
    textField4.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            details[1] = textField4.getText();
            btnGo.setEnabled(true);
            btnGo.requestFocusInWindow();

        }
    });
    c.fill = GridBagConstraints.HORIZONTAL;
    c.gridx = 2;
    c.gridy = 3;
    pane.add(textField4, c);

    btnGo = new JButton("Go And Get Me My Diploma!");
    btnGo.setEnabled(false);
    btnGo.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {

            JOptionPane.showMessageDialog(null, details[0] + " " + details[1] + " " + details[2]);
        }
    });
    c.fill = GridBagConstraints.HORIZONTAL;
    c.ipady = 0;
    c.weighty = 1.0;
    c.anchor = GridBagConstraints.PAGE_END;
    c.insets = new Insets(10, 0, 0, 0);
    c.gridx = 0;
    c.gridwidth = 4;
    c.gridy = 4;
    pane.add(btnGo, c);
}

private static void createAndShowGUI() {
    JFrame frame = new JFrame("Zagori Mountain Running Diploma Maker");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    addComponentsToPane(frame.getContentPane());

    frame.pack();
    frame.setSize(500, 250);
    frame.setVisible(true);
}

public String[] inputBib() {

    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });

    return details;

}

但是当我在另一个类中调用这个 GUI 时

public class CheckFiles {
InputConsole bibInput = new InputConsole();

String[] detailsInput = bibInput.inputBib();
private static Scanner scanner;

public String bibCorrected()  {

    String yearToCheck = null;
    {

        if (detailsInput[2] == "2016") {
            yearToCheck = "ZMR2016.txt";
        } else if (detailsInput[2] == "2015") {
            yearToCheck = "ZMR2015.txt";
        } else if (detailsInput[2] == "2014") {
            yearToCheck = "ZMR2014.txt";
        } else {
            yearToCheck = "ZMR2013.txt";

为了获得那个String[]，我得到了一个java.lang.NullPointerException。我知道我得到这个是因为程序不会等待 GUI 获取所有输入并将可返回的 String[] 归档为 null。我想我知道我必须对 wait() 和 notify() 做一些事情，但我似乎不明白到底是什么。 提前感谢您的任何建议。 （对于长线程非常抱歉）

Answer 1

您可以在 GUI 上添加一个按钮，该按钮将调用 bibCorrected() 方法。目前您正在显示然后返回，因此数组为空，并且 arg 2 不存在因此抛出 NPE。这可能是解决问题的最简单方法。

另外，最好使用 String.equals(String) 而不是 ==。阅读这篇 StackOverflow 帖子What is the difference between == vs equals() in Java?