java - How to make an On/off 'signal lamp' using DataInputStream? -

i'd make program can send signal through network using datainputstream have trouble algorithm.

the program simple actually. need making 2 guis. 1 color button (red, yellow, , blue button), 1 3 shapes changes color when click button.

so here client (signal buttons) code

connect.addactionlistener(new actionlistener(){     public void actionperformed(actionevent e){         try{                 string str = tf.gettext();                 s = new socket(str,54321);                 out = s.getoutputstream();                 dos = new dataoutputstream(out);                 system.out.println("connection succeeded");             }catch(exception ex){                 system.out.println("connection error");             }         }     });     jbutton disconnect = new jbutton ("切断");     disconnect.addactionlistener(new actionlistener(){         public void actionperformed(actionevent e){             try{                 dos.close();                 out.close();                 s.close();                 system.out.println("connection closed");             }catch(exception ex){                 system.err.println("error -" +ex.tostring());             }         }        }); 

and here server (signal lamps). problem. sorry if code not efficient.

import javax.swing.jpanel; import javax.swing.*; import java.awt.event.*; import java.awt.*; import java.net.*; import java.io.*;  public class lamp extends jframe{     serversocket ss = null;     socket s = null;     inputstream in = null;     datainputstream dis = null;     string iro;     int s1,s2,s3;     private container contentpane;     public lamp(string title){         super(title);             addwindowlistener(new windowadapter(){             public void windowclosing(windowevent we){                 system.exit(0);             }         });         setsize(670,300);         setresizable(false);         setvisible(true);     }     public void paint(graphics g){         g.setcolor(color.blue);         g.drawoval(10,50,200,200);         g.setcolor(color.yellow);         g.drawoval(220,50,200,200);         g.setcolor(color.red);         g.drawoval(430,50,200,200);         try{             ss = new serversocket(54321);             s = ss.accept();             in = s.getinputstream();             dis = new datainputstream(in);             iro = dis.readutf();             s1 = 0;             s2 = 0;             s3 = 0;             if(iro=="1"){                 if(s1==0){                     s1=1;                     g.setcolor(color.blue);                     g.filloval(10,50,200,200);                     system.out.println("received blue");                 }else{                     s1=0;                     g.setcolor(color.blue);                     g.filloval(10,50,200,200);                     system.out.println("received blue");                 }                    }             //its same statement yellow , red         }catch(exception e){             system.out.println("error");         }      }     public static void main(string []args){         new lamp("lamp");     } } 

the result

error error error error error 

any idea?