多线程(多线程-死锁)_JAVA_编程开发_程序员俱乐部

class="java">
/**
 * 线程同步死锁问题
 * 
 * 造成原因：线程持a持有一个锁，线程b也持有一个锁，a线程想进入b线程中运行，b线程想
 * 进入a线程中运行，a线程不释放锁，b线程也不释放锁。就这样就成为死锁，程序没有了反应。
 * */
class Test implements Runnable
{
	private boolean flag;
	public Test(boolean flag) {
		this.flag=flag;
	}
	@Override
	public void run() 
	{
		if(flag)
		{
			synchronized (Mylock.locka) {
				System.out.println("if locka");
				synchronized (Mylock.lockb) {
					System.out.println("if lockb");
				}
			}
		}
		else 
		{
			synchronized (Mylock.lockb) {
				System.out.println("else lockb");
				synchronized (Mylock.locka) {
					System.out.println("else locka");
				}
			}
		}
	}
}
//锁类
class Mylock
{
	static Object locka = new Object();
	static Object lockb = new Object();
}
//测试
class DeathLockDemo{
	public static void main(String[] args) {
		Thread t1 = new Thread(new Test(true));
		Thread t2 = new Thread(new Test(false));
		
		t1.start();
		t2.start();
	}
}