死锁示例程序

public class deadlock {/**一个简单的死锁类 * 在一个Runnable实现类中模拟两个进程的执行内容； * 当flag == true时模块1（线程1）执行，先执行锁外程序（不受锁限制），再锁定锁1 * （str对象）执行100到1的输出, * 然后锁定锁2（str1对象），即需要得到锁2才能继续执行； * 当flag == false时模块2（线程2）执行，先锁定锁2（str1对象）执行1到100的输出, * 然后锁定锁1（str对象），即需要得到锁1才能继续执行； * 所以此时两个线程互相等待对方释放手里的锁，导致程序阻塞，造成死锁。 */public static void main(String[] args) {// TODO 自动生成方法存根deadtest tt0 = new deadtest();// TxtThread tt1 = new TxtThread();// TxtThread tt2 = new TxtThread();// TxtThread tt3 = new TxtThread();tt0.flag = false;new Thread(tt0).start();deadtest tt1 = new deadtest();tt1.flag = true;new Thread(tt1).start();// new Thread(tt0).start();// new Thread(tt0).start();// new Thread(tt1).start();// new Thread(tt2).start();// new Thread(tt3).start();}}class deadtest implements Runnable {static String str = new String();static String str2 = new String();boolean flag;public void run() {if (flag == true) {for (int i = 1; i <= 20; i++) {try {Thread.sleep(10);} catch (Exception e) {e.getMessage();}System.out.println("鎖之外");}synchronized (str) {int num = 100;while (num > 0) {try {Thread.sleep(10);} catch (Exception e) {e.getMessage();}System.out.println(Thread.currentThread().getName()+ "this is 模块1锁1 " + num--);}synchronized (str2) {int num2 = 100;for (int j = 0; j <= num2; j++) {try {Thread.sleep(10);} catch (Exception e) {e.getMessage();}System.out.println(Thread.currentThread().getName()+ "this is 模块1锁2 " + j);}}}}if (flag == false) {synchronized (str2) {int num2 = 100;for (int j = 0; j <= num2; j++) {try {Thread.sleep(10);} catch (Exception e) {e.getMessage();}System.out.println(Thread.currentThread().getName()+ "this is 模块2锁2 " + j);}synchronized (str) {int num = 100;while (num > 0) {try {Thread.sleep(10);} catch (Exception e) {e.getMessage();}System.out.println(Thread.currentThread().getName()+ "this is模块2锁1 " + num--);}}}}}}