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display error message on applet

Posted on 2004-04-07
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Last Modified: 2010-03-31
Trying to display error message on applet if wrong text file name is typed in the myTxtBox

My code so far:-



//<APPLET code=Lou2.class width=400 height=200> </APPLET>


import java.applet.*;
import java.awt.*;
import java.io.*;
import java.net.*;
import java.awt.event.*;
public class Lou2 extends Applet implements ActionListener {
     Label myLabel;
     TextArea myBox;
     TextField myTxtbox; //Added new textbox onto applet into which file name can be typed for 23a.
     Button mybtn;
     public void init() {
          myLabel = new Label(
          "The text area shows the information read from the file on the server");
          myBox = new TextArea("", 4, 20);
          myTxtbox = new TextField(20);
          myTxtbox.setText("readthis.txt");
          mybtn = new Button("Load File into Text Area");
          add(myLabel);
          add(myBox);
          add(myTxtbox);
          add(mybtn);
          mybtn.addActionListener(this);
     } // end of init()
     public void actionPerformed(ActionEvent e) {
          loadFile();
     }//end action performed
     public void loadFile() {
          try {
               URL myURL = new URL(getDocumentBase(), myTxtbox.getText());
               // open file on server
               URLConnection myConn = myURL.openConnection();
               InputStreamReader isr = new InputStreamReader(myConn
                         .getInputStream());
               BufferedReader bufr = new BufferedReader(isr);
               String line;
               line = bufr.readLine(); // read ahead  
               while (line != null) {
                    myBox.append(line + "\n");
                    line = bufr.readLine();
               } // end of while          
          } // end of try
          catch (MalformedURLException me) {
               System.out.println("Bad URL encountered" + me);
          } catch (IOException ioe) {
               System.out.println("IO Exception" + ioe);

          }
     }
} // end of Applet

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Question by:buglouie
  • 3
3 Comments
 
LVL 86

Accepted Solution

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CEHJ earned 500 total points
ID: 10778307
a. you should be doing loadFile in a separate thread
b. you should make loadFile be boolean then
c. you can do if (!loadFile) ....... (set a label text to show error result)
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LVL 86

Expert Comment

by:CEHJ
ID: 10778334
public void actionPerformed(ActionEvent e) {
      Thread fileLoader = new Thread(new Runnable() {
            public void run() {
                  if (!loadFile()) {
                        label.setText("Fileload failed");
                  }
            }    
      });
      fileLoader.start()

}//end action performed
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 10778416
8-)
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