【面试回顾】面试和多线程的一点心得 - 黑马程序员技术交流社区

public class Test02 {
public static void main(String[] args) {
// 测试
final Person p1 = new Person("张三", 1);
final Person p2 = new Person("李四", 0);
Thread t1 = new Thread() {
public void run() {
while (true) {
try {
if (Person.getFlag() == p1.getTargetFlag()) {
p1.savingMoney();
Person.setFlag(0);
p1.notifyAll(); //错误1：锁对象已经在执行完savingMoney后被释放了，发生IllegalMonitorState异常
} else {
p1.wait(); //错误2：锁对象已经在执行完savingMoney后被释放了，发生IllegalMonitorState异常
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
};
Thread t2 = new Thread() {
public void run() {
while (true) {
try {
if (Person.getFlag() == p2.getTargetFlag()) {
p2.savingMoney();
Person.setFlag(1);
p2.notifyAll(); //错误1a同上
} else {
p2.wait(); //错误2a同上
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
};
t1.start();
t2.start();
}
}
class Person {
private String name;
private static int flag;
private int targetFlag;
static {
flag = 0;
}
Person(String name, int targetFlag) {
this.name = name;
this.targetFlag = targetFlag;
}
public String getName() {
return name;
}
public int getTargetFlag() {
return targetFlag;
}
public synchronized void savingMoney() throws Exception { //此处的synchronzied关键字的锁对象是this
System.out.print(this.getName());
System.out.println("向银行存入500元");
}
public static int getFlag() {
return flag;
}
public static void setFlag(int flag) {
Person.flag = flag;
}
}

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Can you pass a Thread object to Executor.execute? Would such an invocation make sense?
能否将Thread对象传入Executor并且运行？这样做是否有意义？

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Compile and run BadThreads.java:
public class BadThreads {
static String message;
private static class CorrectorThread
extends Thread {
public void run() {
try {
sleep(1000);
} catch (InterruptedException e) {}
// Key statement 1:
message = "Mares do eat oats.";
}
}
public static void main(String args[])
throws InterruptedException {
(new CorrectorThread()).start();
message = "Mares do not eat oats.";
Thread.sleep(2000);
// Key statement 2:
System.out.println(message);
}
}
The application should print out "Mares do eat oats." Is it guaranteed to always do this? If not, why not? Would it help to change the parameters of the two invocations of Sleep? How would you guarantee that all changes to message will be visible in the main thread?

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