Question

大家好，我正在研究用Java制作的十六进制转储实用程序。我在使用hex / ascii逻辑之前使用的扫描仪时遇到了一些问题。

现在我有逻辑和一些其他的东西被排除在调试的原因，但如果有人知道发生了什么，我想知道！提示非常感谢。

package filedumputility;

import javax.swing.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class FileDump extends JFrame {

public FileDump() throws Exception{
    setTitle("File Dump Utility");
    add(new DumpPanel());
}

//Main method
public static void main(String[] args) throws Exception {
    FileDump frame = new FileDump();
    frame.setSize(500, 250);
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
    frame.setVisible(true);
}
//Class to creaste components
class DumpPanel extends JPanel {
    private JFileChooser fileChooser = new JFileChooser();
    private JTextArea dumpArea = new JTextArea(11, 20);
    private JTextField fileName = new JTextField(16);
    private JButton newButton = new JButton("New File");
    private JButton clearButton = new JButton("Clear");
    private JButton dumpButton = new JButton("Dump File");
    private JScrollPane scrollPane = new JScrollPane(dumpArea);
    private JPanel p = new JPanel();
    private Scanner input;

    //Class to add components and read the file
    public DumpPanel() throws Exception {
        p.setLayout(new FlowLayout());
        setLayout(new BorderLayout());

        add(p, BorderLayout.NORTH);
        p.add(fileName);
        p.add(dumpButton);
        p.add(newButton);
        p.add(clearButton);
        add(scrollPane, BorderLayout.SOUTH);

        dumpArea.setEditable(false);
        fileName.setEditable(false);

        //Create event for the new file button
        newButton.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){                    

                if(fileChooser.showOpenDialog(null)
                        == JFileChooser.APPROVE_OPTION) {

                    //Get the file
                    java.io.File file = fileChooser.getSelectedFile();

                //Set file name bar to the selected file
                fileName.setText(file.getName());
                }
            }
        });

        dumpButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if(fileChooser.showOpenDialog(null)
                        == JFileChooser.APPROVE_OPTION) {

                    //Get the file
                    java.io.File file = fileChooser.getSelectedFile();
                    //Create scanner
                    Scanner input = new Scanner(file);

                }
            }
        });

        clearButton.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                dumpArea.setText(" ");
                fileName.setText(" ");
            }
        });
    }
}
}

Answer 1

为了让您的示例进行编译，您可以将new Scanner行包装在try catch中，如下所示：

            Scanner input = null;
            try {
                input = new Scanner(file);
            } catch(FileNotFoundException ex) {
                // handle this condition appropriately
            }

一旦这样做，您就可以按照预期的方式继续处理文件行。

Answer 2

我能看到的唯一问题是Scanner构造函数throws FileNotFoundException;因此，您需要将其封装在try / catch块中。

看起来应该是这样的（仅限初学者）：

dumpButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        if(fileChooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) {

            //Get the file
            java.io.File file = fileChooser.getSelectedFile();
            //Create scanner
            try {
                Scanner input = new Scanner(file);
            } catch (FileNotFoundException ex) {
                System.err.println("Error opening " + file.getName());
            }
        }
    }
});

您可能还会发现Java Exceptions Tutorial有帮助。

ActionListener / actionPerformed类中的扫描程序错误

2 个答案: