Question

I had a quiz for Threads last week and I got these 2 questions wrong. I was wondering if anyone can help me get the right answer for these. Thanks.

Are there any results that CANNOT be the output of this program?
I get confused with these sort of questions. I ran the program and found that Bbccaa is possible, aaccbb is possible, ccbbaa is possible and aabbcc is possible.

public class Test4 extends Thread { //8
  public Test4(String name) { 
   super(name); 
  } 
  public void run() { 
   print(getName()); 
  } 
  public static synchronized void print(String n) { 
   System.out.print(n); 
   try { sleep(...); } catch (Exception ex) {} // unspecified random time 
   System.out.print(n); 
  } 
  public static void main(String argv[]) throws Exception { 
   Test4 ta = new Test4("a"); 
   Test4 tb = new Test4("b"); 
   Test4 tc = new Test4("c"); 
   ta.start(); 
   tb.start(); 
   tc.start(); 
   ta.join(); 
   tb.join(); 
   tc.join(); 
  } 
}

Same question for this code
Abab is possible, baab is possible, baba is possible. I get confused with these sort of questions. Is there any tricks or tips that will help me understand which output is not possible.

public class Test3 extends Thread { 
  public Test3(String name) { 
   super(name); 
  } 
  public void run() { 
   print(getName()); 
  } 
  public static void print(String n) { 
   System.out.print(n); 
   try { sleep(...); } catch (Exception ex) {} 
   System.out.print(n); 
  } 
  public static void main(String argv[]) throws Exception { 
   Test3 ta = new Test3("a"); 
   Test3 tb = new Test3("b"); 
   Test3 tc = new Test3("c"); 
   ta.start(); 
   tb.start(); 
   ta.join(); 
   tb.join(); 
  } 
}

Answer 1

Matthew is right for the first. So it can have anything like aabbcc or ccbbaa as long as it is consecutive, hence the synchronized term.

The second one I think the code wont print out aacc. Tell me if I am wrong