public class TestDeadLock implements Runnable {
public static int flag =1;
public static Object o1;
public static Object o2;
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("flag = "+flag);
if(flag == 1){
synchronized(o1){
try {
Thread.sleep(5000);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
synchronized (o2) {
System.out.println("1");
}
}
if(flag == 0){
synchronized (o2) {
try {
Thread.sleep(5000);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
synchronized (o1) {
System.out.println("0");
}
}
}
}
public static void main(String[] args) {
TestDeadLock td1 = new TestDeadLock();
TestDeadLock td2 = new TestDeadLock();
td1.flag = 1;
td2.flag = 0;
Thread t1 = new Thread(td1);
Thread t2 = new Thread(td2);
t1.start();
t2.start();
}
}flag = 0Exception in thread "Thread-0" Exception in thread "Thread-1" flag = 0java.lang.NullPointerException at Thread.TestDeadLock.run(TestDeadLock.java:26) at java.lang.Thread.run(Unknown Source)java.lang.NullPointerException at Thread.TestDeadLock.run(TestDeadLock.java:26) at java.lang.Thread.run(Unknown Source)上面是运行结果，编译没有问题，求解释。
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