功能性错误，请各位帮忙！ - JAVA论坛

楼主

已结贴√ 问题点数：20 回复次数：5

功能性错误，请各位帮忙！

运行后，弹出的窗口输入数字会实现一个简单的加法运算，但总会把第一个加数丢失，请朋友们帮忙看看是什么原因！

程序代码：

package 练习代码;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.InputMismatchException;
import java.util.Scanner;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class Example9_17 {
    public static void main(String args[]) {
        WindowInput win = new WindowInput();
        win.setTitle("带输入对话框的窗口");
        win.setBounds(80, 90, 280, 300);
    }
}

class WindowInput extends JFrame implements ActionListener {
    JTextArea showResult;
    JButton openInput;
    String regex = "[\\d\\s]+";
    
    WindowInput() {
        openInput = new JButton("弹出输入对话框");
        showResult = new JTextArea();
        add(openInput, BorderLayout.NORTH);
        add(new JScrollPane(showResult), BorderLayout.CENTER);
        openInput.addActionListener(this);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        
        String str = JOptionPane.showInputDialog(this, "输入数字，用空格隔开", "输入对话框", JOptionPane.PLAIN_MESSAGE);
        if(str != null) {
            Scanner scanner = new Scanner(str);
            double sum = 0;
            int k = 0;
            String i = scanner.next();
            if(i.matches(regex)) {
                while(scanner.hasNext()) {
                    try{
                        double number = scanner.nextDouble();
                        if(k == 0)
                            showResult.append(""+number);
                        else
                            showResult.append("+"+number);
                        sum += number;
                        k++;
                    }
                    catch(InputMismatchException exp){
                        String t = scanner.next();
                    }
                }
                showResult.append("="+sum+"\n");
            }
            else
                JOptionPane.showMessageDialog(this, "请输入数字好吗", "警告", JOptionPane.WARNING_MESSAGE);
                
        }
    }
}

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第 2 楼

得分:0

因为你的 String i = scanner.next();已经把空格前的读出来了，我改了一下，还是有点小bug，暂时没想出更好的方法
class WindowInput extends JFrame implements ActionListener {
     JTextArea showResult;
     JButton openInput;
     String regex = "[\\d\\s]+";

     WindowInput() {
         openInput = new JButton("弹出输入对话框");
         showResult = new JTextArea();
         add(openInput, BorderLayout.NORTH);
         add(new JScrollPane(showResult), BorderLayout.CENTER);
         openInput.addActionListener(this);
         setVisible(true);
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     }

     @Override
     public void actionPerformed(ActionEvent e) {
         // TODO Auto-generated method stub

         String str = JOptionPane.showInputDialog(this, "输入数字，用空格隔开", "输入对话框", JOptionPane.PLAIN_MESSAGE);
         if(str != null) {
             Scanner scanner = new Scanner(str);
             double sum = 0;
             int k = 0;
             //String i = scanner.nextLine();
             //if(i.matches(regex)) {
                 while(scanner.hasNext()) {
                     if (!scanner.hasNext(regex))
                     {
                         JOptionPane.showMessageDialog(this, "请输入数字好吗", "警告", JOptionPane.WARNING_MESSAGE);
                         return;
                     }
                     try{
                         double number = scanner.nextDouble();
                         if(k == 0)
                             showResult.append(""+number);
                         else
                             showResult.append("+"+number);
                         sum += number;
                         k++;
                     }
                     catch(InputMismatchException exp){
                         String t = scanner.next();
                     }
                 }
                 showResult.append("="+sum+"\n");
             //}
             //else
            //     JOptionPane.showMessageDialog(this, "请输入数字好吗", "警告", JOptionPane.WARNING_MESSAGE);

         }
     }
}

第 3 楼

得分:20

这样改了下，比较完美了
class WindowInput extends JFrame implements ActionListener {
     JTextArea showResult;
     JButton openInput;
     String regex = "[\\d\\s]+";

     WindowInput() {
         openInput = new JButton("弹出输入对话框");
         showResult = new JTextArea();
         add(openInput, BorderLayout.NORTH);
         add(new JScrollPane(showResult), BorderLayout.CENTER);
         openInput.addActionListener(this);
         setVisible(true);
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     }

     @Override
     public void actionPerformed(ActionEvent e) {
         // TODO Auto-generated method stub

         String str = JOptionPane.showInputDialog(this, "输入数字，用空格隔开", "输入对话框", JOptionPane.PLAIN_MESSAGE);
         if(str != null) {
             Scanner scanner = new Scanner(str);
             double sum = 0;
             int k = 0;
             String i = scanner.nextLine();
             if(i.matches(regex)) {
                 Scanner scanner2 = new Scanner(i);
                 while(scanner2.hasNext()) {
                     try{
                         double number = scanner2.nextDouble();
                         if(k == 0)
                             showResult.append(""+number);
                         else
                             showResult.append("+"+number);
                         sum += number;
                         k++;
                     }
                     catch(InputMismatchException exp){
                         String t = scanner2.next();
                     }
                 }
                 showResult.append("="+sum+"\n");
             }
             else
                 JOptionPane.showMessageDialog(this, "请输入数字好吗", "警告", JOptionPane.WARNING_MESSAGE);

         }
     }
}

第 4 楼

得分:0

既然是浮点数，那么正则应该改为String regex = "[\\d\\s\\.]+";
另外每个数还是要判断小数点的位置和个数

第 5 楼

得分:0

回复 4楼 grmmylbs

嗯，你这样确实是解决了问题，不过步骤繁琐了一下。你说的小数点确实是我忘记啦哈哈，多谢前辈提醒！！另一位前辈帮我改了一下，我觉着这个方法是不错的，你看一下代码

程序代码：

package 练习代码;

 
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.InputMismatchException;
import java.util.Scanner;

 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

 
public class Example9_17 {
    public static void main(String args[]) {
        WindowInput win = new WindowInput();
        win.setTitle("带输入对话框的窗口");
        win.setBounds(80, 90, 280, 300);
    }
}

 
class WindowInput extends JFrame implements ActionListener {
    JTextArea showResult;
    JButton openInput;
    String regex = "[\\d\\s]+";
     
    WindowInput() {
        openInput = new JButton("弹出输入对话框");
        showResult = new JTextArea();
        add(openInput, BorderLayout.NORTH);
        add(new JScrollPane(showResult), BorderLayout.CENTER);
        openInput.addActionListener(this);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

 
    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
         
        String str = JOptionPane.showInputDialog(this, "输入数字，用空格隔开", "输入对话框", JOptionPane.PLAIN_MESSAGE);
        if(str != null) {
            Scanner scanner = new Scanner(str);
            double sum = 0;
            int k = 0;
          //  String i = scanner.next();
            if(str.matches(regex)) {
                while(scanner.hasNext()) {
                    try{
                        double number = scanner.nextDouble();
                        if(k == 0)
                            showResult.append(""+number);
                        else
                            showResult.append("+"+number);
                        sum += number;
                        k++;
                    }
                    catch(InputMismatchException exp){
                        String t = scanner.next();
                    }
                }
                showResult.append("="+sum+"\n");
            }
            else
                JOptionPane.showMessageDialog(this, "请输入数字好吗", "警告", JOptionPane.WARNING_MESSAGE);
                 
        }
    }
}

第 6 楼

得分:0

哦，我陷入Scanner scanner = new Scanner(System.in);里面了，没想到这个。