Interesting. IIUC, not all implementations are so well behaved, though.
For some years, Michael B. Feldman has taught students of Ada and Java
about threads using code similar to that below, which he kindly shares
with us.

<code>
import  java.util.Random;

/**---------------------------------------------------------------
 * Demo of simple thread class
 * Last Modified: March 2008
 * @author Michael B. Feldman, mfeldman at gwu.edu
 *--------------------------------------------------------------*/

public class ShowThreads {

  public static void main(String args[]) {
    SimpleThread ThreadA = new SimpleThread("A", 5, 1);
    SimpleThread ThreadB = new SimpleThread("B", 7, 21);
    SimpleThread ThreadC = new SimpleThread("C", 4, 41);

    SafeScreen.clearScreen();
    ThreadA.start();
    ThreadB.start();
    ThreadC.start();
  }

class SimpleThread extends Thread {

  private static final Random random = new Random();
  private String name = "Default";
  private int count = 0;
  private int column = 0;

  // constructor
  public SimpleThread(String name, int count, int column) {
    this.name = name;
    this.count = count;
    this.column = column;
  }

  // run method invoked when 'start' called
  public void run() {
    for(int i = 1; i <= count; i++) {
      int nap = random.nextInt(7) + 1;
      SafeScreen.write(name + " naps " + nap + " secs", i, column);
      try {
        sleep(nap * 1000);
      }
      catch(InterruptedException e) {} // ignored
    }
  }

class SafeScreen {

  public static synchronized void clearScreen() {
    System.out.print("\033" + "[2J");
  }

  public static synchronized void write(
      String item, int row, int col) {
    System.out.println("\033" + "[" + row + ";" + col + "f" + item);
  }

[The code is Professor Feldman's; any errors are mine.]