Program enters infinite loop.

Question

this is the first program i'm writing with sockets and is also a step towards making a chat application. my problem is that the program enters infinite loop.
package server;
import java.net.*;
import java.io.*;
class Server
    public static void main(String[] args) throws Exception
        ServerSocket ss = new ServerSocket(9090);
        Socket soc = ss.accept();
        BufferedReader in = new BufferedReader(new InputStreamReader(soc.getInputStream()));
        String str = in.readLine();
        while(str!="")
            System.out.println(str);
            str = in.readLine();
        soc.close();
        ss.close();
}this was the server - a seperate application. below is a part of the client - a seperate application
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        try
            InetAddress ip = InetAddress.getByName("127.0.0.1");
            Socket soc = new Socket(ip,9090);
            PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(soc.getOutputStream())),true);
            str_out = jTextArea2.getText();
            while(str_out!="")
                out.println(str_out);
                str_out = jTextArea2.getText();
            soc.close();
        catch(Exception e)
            System.out.println("Error sending message");
    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        str_out = "";
        jTextArea2.setText(str_out);
    }  when i press button send (jButton1) the text from the text area jTextArea2 is supposed to go to the server and then the server should display it in its out put screen. i tried sending hello and the server went on printing hello continously.
pleas help.

Answer 1

String str = in.readLine();
while(str!="")
System.out.println(str);
str = in.readLine();
}You need to test for (str != null) above too, or instead of str != "".