Exemplo de testabilidade - Chamada Assíncrona

MyMath.java

class TaskResult {
  double value;
  public synchronized void set(double value) {
    this.value = value;
  }
  public double get() {
    return value;  
  }
}


public class MyMath {
	
  public double syncPI (int prec) {
    return 3.1415926;
  }
	
  public void asyncPI(int prec, TaskResult task) {
    new Thread (new Runnable() {
               public void run() { 
                 double pi = syncPI(prec); // compute PI 
            	 task.set(pi); 
               }     
        }).start();
  }
	
  public static void main (String [] args) {
    MyMath m = new MyMath();
    TaskResult task = new TaskResult();
    m.asyncPI(10, task);
    try { Thread.sleep (1000); } catch (InterruptedException ex) {}
    System.out.println(task.get());
  }

}