Synchronized Block demo : Lock Synchronize « Threads « Java

Synchronized Block demo

Synchronized Block demo
public class SyncBlock extends Object {
  private Object longLock;

  public SyncBlock() {
    longLock = new Object();

  public void doStuff() {
    print("about to try to get exclusive access " + "to longLock");

    synchronized (longLock) {
      print("got exclusive access to longLock");
      try {
      } catch (InterruptedException x) {
      print("about to relinquish exclusive access to " + "longLock");

  private static void print(String msg) {
    String name = Thread.currentThread().getName();
    System.err.println(name + ": " + msg);

  private static Thread launch(final SyncBlock sb, String name) {

    Runnable r = new Runnable() {
      public void run() {
        print("in run()");

    Thread t = new Thread(r, name);

    return t;

  public static void main(String[] args) {
    try {
      SyncBlock sb = new SyncBlock();

      Thread t1 = launch(sb, "T1");

      Thread t2 = launch(sb, "T2");
      Thread t3 = launch(sb, "T3");


      print("about to interrupt T2");
      print("just interrupted T2");

    } catch (InterruptedException x) {


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