StringBuffer when used with multi thread show output in UnSynchronize way.

Question

below is my code :-
public class Two implements Runnable
     //thread safe
static StringBuffer builder=new StringBuffer("output:1");
Two(StringBuffer builder)
          this.builder=builder;
     public void run()
          System.out.println("Printed by "+Thread.currentThread().getName()+" : "+builder.append(" output:5"));
public static void main(String s[])
     builder.append(" output:2");
     Two d1=new Two(builder);
     Thread t1=new Thread(d1);
     Thread t2=new Thread(d1);
     Thread t3=new Thread(d1);
     t1.start();
     t2.start();
     t3.start();
     builder.append(" output:3");
     builder.append(" output:4");
     System.out.println("Printed by "+Thread.currentThread().getName()+" : "+builder);
when the program is executed it show different output in corresponds to the order of call and it is not showing thread saftey.

Answer 1

thanks tolls ,
below is my output : -
first time when i run the progra"_
Printed by Thread-1 : output:1 output:2 output:5 output:5 output:5
Printed by Thread-0 : output:1 output:2 output:5
Printed by main : output:1 output:2 output:5 output:5 output:5 output:3 output:4
Printed by Thread-2 : output:1 output:2 output:5 output:5
second time when i run the program_
Printed by Thread-0 : output:1 output:2 output:5
Printed by Thread-2 : output:1 output:2 output:5 output:5 output:3 output:4 output:5
Printed by Thread-1 : output:1 output:2 output:5 output:5
Printed by main : output:1 output:2 output:5 output:5 output:3 output:4
see the order of output. there is no synchronization among threads . Where as StringBuffer is thread safe but the order of output is different at each time. My question is just that
how to achieve synchronization among threads.