在需要线程同步的时候如何选择合适的线程锁?
例：选择可以存入到常量池当中的对象，String对象等
public class SyncTest { private String name = "name"; public void method(String flag) { synchronized (name) { System.out.println(flag + ", invoke method ...."); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } public static void main(String[] args) { SyncTest test1 = new SyncTest(); SyncTest test2 = new SyncTest(); MyThread1 myThread1 = new MyThread1(); MyThread1 myThread2 = new MyThread1(); myThread1.syncTest = test1; myThread2.syncTest = test1; MyThread1 myThread3 = new MyThread1(); MyThread1 myThread4 = new MyThread1(); myThread3.syncTest = test2; myThread4.syncTest = test2; myThread1.start(); myThread2.start(); myThread3.start(); myThread4.start(); } }
线程类：
public class MyThread1 extends Thread { SyncTest syncTest; @Override public void run() { syncTest.method(this.getName()); } }
本来应该是要实现线程thread1和thread2同步，线程thread3和thread4同步的，但结果呢?
却是使得线程thread1、thread2、thread3、thread4同步了，很是郁闷。
我推荐选用的同步锁对象：
public class SyncTest { // 特殊的instance变量,用于充当同步锁的对象 private byte[] lock = new byte[0]; public void method(String flag) { synchronized (lock) { System.out.println(flag + ", invoke method f...."); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } public static void main(String[] args) { SyncTest test1 = new SyncTest(); SyncTest test2 = new SyncTest(); MyThread1 myThread1 = new MyThread1(); MyThread1 myThread2 = new MyThread1(); myThread1.syncTest = test1; myThread2.syncTest = test1; MyThread1 myThread3 = new MyThread1(); MyThread1 myThread4 = new MyThread1(); myThread3.syncTest = test2; myThread4.syncTest = test2; myThread1.start(); myThread2.start(); myThread3.start(); myThread4.start(); } }
推荐使用0长度的byte数组充当同步锁对象，不会产生很诧异的错误同时不会占用很大内存。
本文转自Orson博客园博客，原文链接：http://www.cnblogs.com/java-class/p/3145442.html，如需转载请自行联系原作者