How to improve Jslider

[JohnST]

I'm using the following to control a dimmer. The problem is very slow to react. I would like some suggestions of how to improve this code. I would like to open a socket and keep it open and send str value from slider to output stream. I guess what I would like to do is bind the value from slider to output stream, but only open socket once.

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

public class CreateSlider{
  Socket c4Socket = null;
  JSlider slider;
  JLabel label;
  public static void main(String[] args){
    CreateSlider cs = new CreateSlider();
  }

  public CreateSlider(){
    JFrame frame = new JFrame("Light Dimmer");
    slider = new JSlider();
    slider.setValue(0);
    slider.addChangeListener(new MyChangeAction());
    label = new JLabel("0");
    JPanel panel = new JPanel();
    panel.add(slider);
    panel.add(label);
    frame.add(panel, BorderLayout.CENTER);
    frame.setSize(400, 200);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }

  public class MyChangeAction implements ChangeListener{
    public void stateChanged(ChangeEvent ce){
      int value = slider.getValue();
      String str = Integer.toString(value);
      label.setText(str);
    
      DataOutputStream os = null;
        

// Try to open output stream
        try {
            c4Socket = new Socket("192.168.1.107", 5020);
            os = new DataOutputStream(c4Socket.getOutputStream());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host");
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to controller");
        }
// If everything has been initialized then we want to write some data
// to the socket we have opened a connection to on port 5020
    if (c4Socket != null && os != null) {
            try {
// message

            
                os.writeBytes("<c4soap name=\"SendToDeviceAsync\" session=\"0\" operation=\"RWX\" category=\"composer\" async=\"True\"><param name=\"iddevice\" type=\"number\">218</param><param name=\"data\" type=\"string\"><devicecommand owneridtype=\"\" owneriditem=\"-1\"><command>SET_LEVEL</command><params><param><name>LEVEL</name><value type=\"INTEGER\"><static>");
                os.writeBytes(str);
                os.writeBytes("</static></value></param></params></devicecommand></param></c4soap>\0");
                
                
       
                

// close the socket
        os.close();
             
                c4Socket.close();   
            } catch (UnknownHostException e) {
                System.err.println("Trying to connect to unknown host: " + e);
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
          }
       }
    }         
 }

[quad64bit]

I think the problem lies in that you are trying to create an entirely new output stream every time there is a change -- which can happen several times per second.

I think it would be better to create the server connection when the app is launched. Then on a change event, simply send the updated information.

If you really want to make it efficient, only send the update once the user has let go of the mouse button -- or add an 'Update' button that submits the changes only on click.

[JohnST]

Thanks for the suggestions it's working much better now. My only other question is where should I close the socket or do I need to?

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

public class CreateSlider{
  private static Socket c4Socket = null;
  private static DataOutputStream os = null;
  JSlider slider;
  JLabel label;
  
  public static void main(String[] args){
    try {
  c4Socket = new Socket("192.168.1.107", 5020); 
  os = new DataOutputStream(c4Socket.getOutputStream());
   } catch (UnknownHostException e) {
            System.err.println("Don't know about host");
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to controller");
        }
    CreateSlider cs = new CreateSlider();
  
     }
  public CreateSlider(){
    
    JFrame frame = new JFrame("Light Dimmer " );
    slider = new JSlider(JSlider.VERTICAL);
    slider.setValue(0);
    slider.addChangeListener(new MyChangeAction());
    label = new JLabel("0");
    JPanel panel = new JPanel();
    panel.add(slider);
    panel.add(label);
    frame.add(panel, BorderLayout.CENTER);
    frame.setSize(400, 300);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }

  public class MyChangeAction implements ChangeListener{
    public void stateChanged(ChangeEvent ce){
      int value = slider.getValue();
      String str = Integer.toString(value);
      label.setText(str);
      if (!slider.getValueIsAdjusting()){      
      if (c4Socket != null && os != null) {
            try {

                os.writeBytes("<c4soap name=\"SendToDeviceAsync\" session=\"0\" operation=\"RWX\" category=\"composer\" async=\"True\"><param name=\"iddevice\" type=\"number\">218</param><param name=\"data\" type=\"string\"><devicecommand owneridtype=\"\" owneriditem=\"-1\"><command>SET_LEVEL</command><params><param><name>LEVEL</name><value type=\"INTEGER\"><static>");
                os.writeBytes(str);
                os.writeBytes("</static></value></param></params></devicecommand></param></c4soap>\0");
                
            } catch (UnknownHostException e) {
                System.err.println("Trying to connect to unknown host: " + e);
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
        }
      }
    }
  }
}

[quad64bit]

My only other question is where should I close the socket or do I need to?

Well, you technically don't have to close it, eventually the other end will time out. However, if you have a 'server' listening for a 'client[s]' then it'd be a nice idea to have each client close the socket when closing the client. You could do it when the window closes for example - I believe you can override the default window close behavior and add in a close socket statement before the application terminates -- that way when a user clicks the close button, it disconnects the quits.