Java applet not completing

Question

My applet works for the most part, but there is something askew with it. My code to notify the user that they need to enter a file name WORKS. But that is the end of it, as notifying the user they didn't enter text doesn't work, and neither does the writing of the text to a file.

It's as if my program breaks half way through. I was hopeful someone could just take a look at the code and let me know of anything obvious. I've been starring at it for 6 hours and don't trust my eyes anymore. The applet is pretty basic and straight forward. The user enters a file name of a txt file in the working directory, and whataver they then type in the test field is written to the file.

import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Color;
import java.awt.HeadlessException;
import java.awt.Label;
import java.awt.TextArea;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import javax.swing.JOptionPane;

public class wwalker2 extends Applet {

    Button write = new Button("WriteToFile");
    Label label1 = new Label("Enter the file name:");
    TextField text = new TextField(20);
    Label label2 = new Label("Write your text:");
    TextArea area = new TextArea(10, 20);

    public void init() {
        add(label1);
        label1.setBackground(Color.orange);
        add(text);
        add(label2);
        label2.setBackground(Color.orange);
        add(area);
        add(write, BorderLayout.CENTER);
        write.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent z) {
                WriteText writeText = new WriteText();
            }
        });
    }

    public class WriteText {

        WriteText() {
            try {
                String str = text.getText();
                if (str.equals("")) {
                    JOptionPane.showMessageDialog(null,
                    "It's not that smart... You have to enter the path and filename");
                    text.requestFocus();
                } else {
                    File f = new File(str);
                    if (f.exists()) {
                        BufferedWriter out = new BufferedWriter(new FileWriter(f, true));
                        if (area.getText().equals("")) {
                            JOptionPane.showMessageDialog(null, "You haven't written anything yet!");
                            area.requestFocus();
                        } else {
                            out.write(area.getText());
                            if (f.canWrite()) {
                                JOptionPane.showMessageDialog(null, "There is now some text in " + str);
                                text.setText("");
                                area.setText("");
                                text.requestFocus();
                            } else {
                                JOptionPane.showMessageDialog(null, "There isn't any text in " + str);
                            }
                            out.close();
                        }
                    } else {
                        JOptionPane.showMessageDialog(null, "Error 404 File not found!");
                        text.setText("");
                        text.requestFocus();
                    }
                }
            } catch (HeadlessException | IOException x) {
            }
        }
    }
}

Can't you "try and catch" `HeadlessException` earlier than that? — fge, Jun 30 '13 at 03:51
1) Why code an applet? If it is due due to spec. by teacher, please refer them to [Why CS teachers should stop teaching Java applets](http://programmers.blogoverflow.com/2013/05/why-cs-teachers-should-stop-teaching-java-applets/). 2) Why AWT rather than Swing? See this answer on [Swing extras over AWT](http://stackoverflow.com/a/6255978/418556) for many good reasons to abandon using AWT components. If you need to support older AWT based APIs, see [Mixing Heavyweight and Lightweight Components](http://www.oracle.com/technetwork/articles/java/mixing-components-433992.html). — Andrew Thompson, Jun 30 '13 at 06:24

score 1 · Answer 1 · answered Jun 30 '13 at 04:00

Two things.

One, applets tend to have very strict sand box security restrictions, notably, the ability to to write files.

Two, In your try-catch block, you should be showing some kind of message or logging the exception.

} catch (HeadlessException | IOException x) {
    JOptionPane.showMessageDialog(this, "Failed to write because of " + x.getMessage());
    x.printStackTrace();
}

I would also recommend that you ditch the AWT framework in favor of the Swing framework - IMHO

score 0 · Answer 2 · answered Jun 30 '13 at 03:56

0

Just thinking around a scenario when there is text but empty text something like " ", that may be the case. Using a trim around the input string may help you to avoid this problem. This may be a safer if check:

if("".equals(str.trim()))

answered Jun 30 '13 at 03:56

Juned Ahsan

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Java applet not completing

2 Answers2