public class Gate { private int counter = 0; private String name = "Nobody"; private String address = "Nowhere"; public synchronized void pass(String name, String address) { this.counter++; this.name = name; try { Thread.sleep(1000); } catch (InterruptedException e) { } this.address = address; check(); } public String toString() { return "No." + counter + ": " + name + ", " + address; } private void check() { if (name.charAt(0) != address.charAt(0)) { System.out.println("***** BROKEN ***** " + toString()); } } }
public class UserThread extends Thread { private final Gate gate; private final String myname; private final String myaddress; public UserThread(Gate gate, String myname, String myaddress) { this.gate = gate; this.myname = myname; this.myaddress = myaddress; } public void run() { System.out.println(myname + " BEGIN"); while (true) { gate.pass(myname, myaddress); } } }
public class Main { public static void main(String[] args) { System.out.println("Testing Gate, hit CTRL+C to exit."); Gate gate = new Gate(); new UserThread(gate, "Alice", "Alaska").start(); new UserThread(gate, "Bobby", "Brazil").start(); new UserThread(gate, "Chris", "Canada").start(); } }
Gate 类中的方法,同步关键字的有无。 执行程序看看。