🚀 go-pugleaf

I'm going to be diving into servlet programming shortly and I feel now is a
good time to wrap my brain around threads and the keyword synchronized.

From the reading I have done and the examples I have seen, I believe I can
summarize the use of synchronized in this way:

"If a method accesses (either reads from or writes to) a variable that one
reasonably expects not be constant and that variable is not local to the
method, the accessing code should be synchronized."

For example, I believe this code to be thread-safe since all of the
variables are local.

public class MyClass {
  public int performCalculation(int x, int y) {
    int temp1 = 0; int temp2 = 0;
    temp1 = y + 5;
    temp2 = x / 3;
    return temp1 + temp2;
  }
}

I believe this code to be thread-unsafe since temp2 is not local to the
method and could potential be modified at any point during any execution of
performCalculation.

public class MyClass {
  int temp2 = 0;
  public void setTemp2(int temp2) {this.temp2 = temp2;}
  public int performCalculation(int x, int y) {
    int temp1 = 0;
    temp1 = y + 5;
    temp2 = x / 3;
    return temp1 + temp2;
  }
}

The second example would be made thread-safe again by wrapping the unsafe
section in a sychronized block.

    synchronized {
      temp2 = x / 3;
      return temp1 + temp2;
    }

Am I on the right track? (Am I in the right newsgroup?) My background is in
VB, so threads are one of the new concepts I'm trying to deal with before I
get to deep. Thanks in advance.

-zoltan