java - 防止代码在用户输入之前返回值

Question

我有以下代码通过 JCombo 框从用户获取 2 个输入，然后将获取的输入的值返回给调用函数，但问题是此代码显示框架以获取用户输入，但在用户可以之前按“确定”按钮，它会将空值返回给调用函数。我希望停止此方法中的代码，直到用户按“确定”按钮。 请提出一些建议。

package io;

import java.io.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener;
import java.awt.Insets; 
import java.io.FileNotFoundException;

public class SrcAndTargLangInput implements ActionListener {
    public static JFrame frame;
    public static JComboBox sourcLang;
    public static JComboBox targLang;
    public static JLabel setSrcLang;
    public static JLabel setTargLang;
    public static JButton ok;
    static String[] lang=new String[2];

    public SrcAndTargLangInput(){
        ok = new JButton("Ok");
        ok.setBounds(150,150,100,50);


        frame = new JFrame();
        frame.getContentPane().setLayout(null);

        frame.getContentPane().add(ok);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        Insets ins = frame.getInsets();
        frame.setSize(400+ins.left+ins.right, 200+ins.bottom+ins.top);
        setSrcLang=new JLabel("Source Language");
        frame.getContentPane().add(setSrcLang);
        setSrcLang.setBounds(50, 50, 100, 40);
        setTargLang=new JLabel("Target Language");
        frame.getContentPane().add(setTargLang);
        setTargLang.setBounds(50, 100, 100, 40);
        String[] srcLangList={"English","Spanish","French"};
        sourcLang = new JComboBox(srcLangList);
        frame.getContentPane().add(sourcLang);
        sourcLang.setBounds(250,50,100,40);
        String[] targLangList={"English","Spanish","French"};
        targLang = new JComboBox(targLangList);
        frame.getContentPane().add(targLang);
        targLang.setBounds(250,100,100,40);
        frame.setVisible(true);
        ok.addActionListener(this);

    }
    public static String[] langInfo(){
        SrcAndTargLangInput ob = new SrcAndTargLangInput();
        return lang;
    }

    public void actionPerformed(ActionEvent e){
        lang[0]=(sourcLang.getSelectedItem().toString());
        lang[1]=(targLang.getSelectedItem().toString());
        frame.setVisible(false);
    }
}

调用函数是:

String[] lg = new String[2];
lg = io.SrcAndTargLangInput.langInfo();
System.out.println(lg[0]);
System.out.println(lg[1]);

Answer 1

在代码中，您可以添加一个默认值为 false 的 boolean 变量。

在actionPerformed 方法中将该值设置为true。更新您的 logInfo 方法以使线程 hibernate ，直到不执行任何操作。请看下面的代码。

import java.io.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.Insets; 
import java.io.FileNotFoundException;

public class SrcAndTargLangInput implements ActionListener {
    public static JFrame frame;
    public static JComboBox sourcLang;
    public static JComboBox targLang;
    public static JLabel setSrcLang;
    public static JLabel setTargLang;
    public static JButton ok;
    static String[] lang=new String[2];
    boolean actionPerformed = false;

    public SrcAndTargLangInput(){
        ok = new JButton("Ok");
        ok.setBounds(150,150,100,50);


        frame = new JFrame();
        frame.getContentPane().setLayout(null);

        frame.getContentPane().add(ok);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        Insets ins = frame.getInsets();
        frame.setSize(400+ins.left+ins.right, 200+ins.bottom+ins.top);
        setSrcLang=new JLabel("Source Language");
        frame.getContentPane().add(setSrcLang);
        setSrcLang.setBounds(50, 50, 100, 40);
        setTargLang=new JLabel("Target Language");
        frame.getContentPane().add(setTargLang);
        setTargLang.setBounds(50, 100, 100, 40);
        String[] srcLangList={"English","Spanish","French"};
        sourcLang = new JComboBox(srcLangList);
        frame.getContentPane().add(sourcLang);
        sourcLang.setBounds(250,50,100,40);
        String[] targLangList={"English","Spanish","French"};
        targLang = new JComboBox(targLangList);
        frame.getContentPane().add(targLang);
        targLang.setBounds(250,100,100,40);
        frame.setVisible(true);
        ok.addActionListener(this);

    }
    public static String[] langInfo() throws InterruptedException{
        SrcAndTargLangInput ob = new SrcAndTargLangInput();
        while(!ob.actionPerformed) {
            Thread.sleep(1000);
        }
        return lang;
    }

    public void actionPerformed(ActionEvent e){
        lang[0]=(sourcLang.getSelectedItem().toString());
        lang[1]=(targLang.getSelectedItem().toString());
        actionPerformed = true;
        frame.setVisible(false);
        Thread.currentThread().interrupt();
    }
}