Threads and Gui

[James]

How can I have the run method append to jTextArea1?


/*
* Chat.java
*
* Created on 7 April 2006, 17:53
*/
import java.io.*;
import java.net.*;
import java.util.*;
/**
*
* @author Glen
*/
public class Chat extends javax.swing.JFrame {

/** Creates new form Chat */
public Chat(Socket socket) {
this.socket=socket;
try
{
out = new PrintStream(socket.getOutputStream());
}
catch(Exception e){}
initComponents();
}

/** This method is called from within the constructor to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
// <editor-fold defaultstate="collapsed" desc=" Generated Code ">
private void initComponents() {
jScrollPane1 = new javax.swing.JScrollPane();
jTextArea1 = new javax.swing.JTextArea();
jPanel1 = new javax.swing.JPanel();
jTextField1 = new javax.swing.JTextField();
jButton1 = new javax.swing.JButton();

setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("Chat");
jTextArea1.setColumns(20);
jTextArea1.setRows(5);
jTextArea1.setFocusable(false);
jScrollPane1.setViewportView(jTextArea1);

getContentPane().add(jScrollPane1, java.awt.BorderLayout.CENTER);

jPanel1.setLayout(new java.awt.GridLayout());

jPanel1.add(jTextField1);

jButton1.setText("Send");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});

jPanel1.add(jButton1);

getContentPane().add(jPanel1, java.awt.BorderLayout.SOUTH);

pack();
}// </editor-fold>

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {


//out = new PrintStream(socket.getOutputStream());
String temp=jTextField1.getText();
jTextArea1.append("You: "+temp+"\n");
out.println(temp);
out.flush();
}

/**
* @param args the command line arguments
*/
public static void main(String args[]) {
try {
Socket socket = new Socket("localhost", PORTNUM);
Chat app= new Chat(socket);
app.setSize(500, 400);
app.setLocation(100, 100);
app.setVisible(true);



readThread t=new readThread(socket);
t.start();


//out.close(); socket.close();
}
catch (IOException e) { System.err.println(e); }




}

private Socket socket;
private PrintStream out;
private static final int PORTNUM = 44130;
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JPanel jPanel1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTextArea jTextArea1;
private javax.swing.JTextField jTextField1;
// End of variables declaration
}

class readThread extends Thread
{
private Socket socket;
private DataInputStream in;

public readThread(Socket soc)
{
socket=soc;
}

public void run()
{
try
{
in = new DataInputStream(socket.getInputStream());
String inStr;
while(true)
{
inStr = in.readLine();
System.out.println(inStr);
if(inStr.compareTo("")==0) break;
}
in.close();
}
catch (IOException e) { System.err.println(e); }
}
}

 

[Thomas Hawtin]

How can I have the run method append to jTextArea1?

Just pass the text area in through the "readThread" class' constructor.

In this case you are lucky. Unusually, JTextArea.append is thread-safe.
In most other cases you would need another Runnable inside your run
method. Something like

String line = in.readLine();
if (line == null) {
break;
}
java.awt.EventQueue.invokeLater( // unnecessary in this case
new Runnable() { public void run() {
textArea.append(line);
}}
);


Not relevant to the question but I would suggest: Ignore the J for
variable names of Swing components. Don't just add meaningless number
suffixes to variable names. Stick to the code conventions - always use
initial caps for class names. Don't use inheritance where you don't have
to - JFrame and Thread should rarely be extended.

Tom Hawtin