据我所知,当我希望当前线程停止工作直到另一个线程对同一个互斥对象调用 notify() 时,我想在互斥对象上调用 wait()。这似乎不起作用。
我正在尝试打印线程 1-10。然后等待另一个线程打印 11-20。然后第一个线程将再次打印 21-30
主.java
public class Main {
public static void main(String[] args) throws InterruptedException {
Object mutex = 1;
Thread child1 = new Thread(new Child1(mutex));
Thread child2 = new Thread(new Child2(mutex));
child1.start();
child2.start();
}
}
Child1.java
public class Child1 implements Runnable {
Object mutex;
public Child1(Object mutex){
this.mutex = mutex;
}
public void run() {
synchronized (mutex) {
for(int c = 0; c < 10; c++){
System.out.println(c+1);
}
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
for(int c = 20; c < 31; c++){
System.out.println(c+1);
}
}
}
Child2.java
public class Child2 implements Runnable {
Object mutex;
public Child2(Object mutex) {
this.mutex = mutex;
}
public void run() {
synchronized (mutex) {
for (int c = 11; c < 21; c++) {
System.out.println(c);
}
notify();
}
}
}
输出
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17Exception in thread "Thread-0"
18
19
20
Exception in thread "Thread-1" java.lang.IllegalMonitorStateException
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:502)
at task42.Child1.run(Child1.java:18)
at java.lang.Thread.run(Thread.java:745)
java.lang.IllegalMonitorStateException
at java.lang.Object.notify(Native Method)
at task42.Child2.run(Child2.java:15)
at java.lang.Thread.run(Thread.java:745)
我错过了什么?
最佳答案
您必须将 mutex
引用添加到 wait()
和 notify()
;即,将 wait()
更改为 mutex.wait()
并将 notify()
更改为 mutex.notify()
.
如果没有这个,您将在 this
上调用等待/通知(method()
等同于 this.method()
)
这是您的代码,并进行了适当的更改:
子1.java
public class Child1 implements Runnable {
Object mutex;
public Child1(Object mutex){
this.mutex = mutex;
}
public void run() {
synchronized (mutex) {
for(int c = 0; c < 10; c++){
System.out.println(c+1);
}
try {
mutex.wait(); // Changed here
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
for(int c = 20; c < 31; c++){
System.out.println(c+1);
}
}
}
Child2.java
public class Child2 implements Runnable {
Object mutex;
public Child2(Object mutex) {
this.mutex = mutex;
}
public void run() {
synchronized (mutex) {
for (int c = 11; c < 21; c++) {
System.out.println(c);
}
mutex.notify(); // Changed here
}
}
}
关于java - 如何在 Java 中使用 wait() 和 notify()?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29378687/