public class SyncBlockThread extends Thread {
  SyncBlock block;
  boolean counter1;
  public SyncBlockThread(SyncBlock block, boolean counter1) {
    this.block = block;
    this.counter1 = counter1;
  }
  
  public void run() {
    if(counter1)
      block.inc1();
    else
      block.inc2();
  }
  
  public static void main(String []args) {
    SyncBlock block = new SyncBlock();
    new SyncBlockThread(block, true).start();
    new SyncBlockThread(block, false).start();
  }
}