个人中心
gpt4 book ai didi

java - 无法获取 JTextField 用户输入来搜索文本文件以进行工作

转载 作者：行者123 更新时间：2023-11-30 08:00:40 24 4
gpt4 key购买 nike

似乎无法让扫描仪将 JTextField 中的用户输入与文本文件相匹配。例如:搜索员工号1121，看看是谁。文本文件中的号码和姓名

更新:包含以下更改的完整代码

public class custSearch extends JFrame{
private static final long serialVersionUID = 1L;
public JTextField userInput;

// Declaring Window Name, Size & Functions
public custSearch(){
    super ("Customer Records");
    setSize(630,250);
    setDefaultCloseOperation(EXIT_ON_CLOSE);

    //NumberFormat integerFieldFormatter = NumberFormat.getIntegerInstance();
    //integerFieldFormatter.setGroupingUsed(false);

// Declaring JPanels & New FlowLayouts  
    JPanel p1 = new JPanel();
    p1.setLayout(new FlowLayout(-2));

// Declaring JLabels    
    JLabel cs = new JLabel("Search Phone Number:"); 

// Declaring JButtons
    JButton sb1 = new JButton("Search");

// Declaring JFormattedTextFields
    //JFormattedTextField cNumber = new JFormattedTextField(integerFieldFormatter);
    //cNumber.setColumns(7);
    JTextField cNumber = new JTextField();
    cNumber.setColumns(7);

// Declaring JPanel Layout
    p1.add(cs);
    p1.add(cNumber);
    p1.add(sb1);
    add(p1, BorderLayout.NORTH);

    //Create File & Save Details
    //sb.addActionListener(new ActionListener() {

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

    //      File file = new File("Customers.txt");
    //      try{
    //      if(file.exists()==false){
    //              file.createNewFile();
    //      }
    //      PrintWriter pw = new PrintWriter(new FileWriter(file, true));
    //      pw.println(cNumber.getText());
    //      pw.close();
    //      }catch(IOException e1){
    //          JOptionPane.showMessageDialog(null,"<html>Customer File Could Not Be Created<p>Make Sure Program Has File Write Perssions");
    //      }

    //}
    //});
    sb1.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            try(Scanner sc = new Scanner(new File("Customers.txt"))) {
                while(sc.hasNextInt()) {
                    int cNumber = sc.nextInt();
                    if(cNumber == Integer.parseInt(userInput.getText()))
                        JOptionPane.showMessageDialog(null, "Customer Found" + cNumber);
                    break;
                }
            }
            catch(IOException e1) {
                    JOptionPane.showMessageDialog(null,"Error");

            }

        }

    });
}
}

收到此错误

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at custSearch$1.actionPerformed(custSearch.java:83)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

最佳答案

很难根据您提供的代码找出问题所在。您能提供整个类(class)以及您遇到的错误吗？您似乎还在 if 语句中使用了赋值运算符:

if(sc = cNumber);

if 语句的正确形式是:

if() {

}

或者:

if()
    only one line allowed;

并且您似乎将 Scanner 分配给 int 变量。 cNumber 包含您的下一个 token ，所以我想您要做的就是执行类似

的操作 
if(cNumber == 1121) etc..

如果你有

private JTextField userInput;

它必须对您的 actionPerformed() 可见，然后您可以执行以下操作:

if(cNumber == Integer.parseInt(userInput.getText())) {
     JOptionPane.showMessageDialog(null, "Customer Found" + cNumber);
}

所以尝试写这样的东西:

      @Override
        public void actionPerformed(ActionEvent e) {
            try(Scanner sc = new Scanner(new File("Customers.txt"))) {
                while(sc.hasNextInt()) {
                    int cNumber = sc.nextInt();
                    if(cNumber == Integer.parseInt(userInput.getText()))
                        JOptionPane.showMessageDialog(null, "Customer Found" + cNumber);
                }
            }
            catch(IOException e1) {
                    JOptionPane.showMessageDialog(null,"Error");
            }

更新尝试创建类似代码:抱歉，您的代码很难理解，因为我没有其他组件，例如它继承的类，所以我创建的是一个简单版本你可能需要，抱歉，我有点匆忙，所以我无法很好地发表评论，如果你有任何问题，请随时提出!基本上它可以满足您的要求，只需确保 Customer.txt 与 src 文件夹位于同一文件夹中即可。

所以这里是:

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;

public class Test extends JFrame implements ActionListener {

    private static final long serialVersionUID = 1L;

    private JTextField numberTextField;
    private JButton submitButton;

    public Test() {
        setTitle("Get Phone Number");
        setLayout(new FlowLayout());
        setSize(600, 300);
        setResizable(true);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create TextField, Label and Button
        add(new JLabel("Search Phone Number:"));
        numberTextField = new JTextField(10);
        add(numberTextField);
        submitButton = new JButton("Search");
        add(submitButton);

        //Adding action listener to the button
        submitButton.addActionListener(this);

        setVisible(true);
        pack();
    }

    public static void main(String[] args) {
        new Test();
    }

    public void findNumber(String path, int number) {
        File file = new File(path);

        try {
            Scanner sc = new Scanner(file);

            while(sc.hasNextInt()) {
                int i = sc.nextInt();
                if(i == number) {
                    JOptionPane.showMessageDialog(null, "Phone Number: " + number + " is found!");
                    break;
                }
                else {
                    if(!sc.hasNextInt()) {
                        JOptionPane.showMessageDialog(null, "Sorry  phone number: " + number + " is not found!");
                        break;
                    }
                    continue;
                }
            }
        }
        catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        findNumber("Customers.txt", Integer.parseInt(numberTextField.getText()));
    }
}

关于java - 无法获取 JTextField 用户输入来搜索文本文件以进行工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/31971784/

24 4 0
文章推荐： java - 使用数组解析 Json 对象并在 Java 中使用 Apache Spark 映射到多个对
文章推荐： javascript - 使用 jquery 格式化一个值
文章推荐： javascript - Angularjs 类型错误 :Cannot read property 'GET()' of undefined
文章推荐： javascript - 这是什么意思？ getData([渲染数据]);
行者123
个人简介

我是一名优秀的程序员,十分优秀！

滴滴打车优惠券免费领取
滴滴打车优惠券
全站热门文章
Copyright 2021 - 2024 cfsdn All Rights Reserved 蜀ICP备2022000587号
广告合作:1813099741@qq.com 6ren.com