多线程通信的简单实践

一直觉得对多线程的理解不够深刻，今天抱以学习的心态写了一个多线程的简单示例，话不多说，直接上代码（高手请绕行，谢谢）

public class ThreadTest {
public static int num = 0;
public static void main(String[] args) {
final ThreadTest test = new ThreadTest();
for (int j = 0; j < 5; j++) {
new Thread(new Runnable() {
@Override
public void run() {
test.increase();
}
}).start();
}
for (int j = 0; j < 5; j++) {
new Thread(new Runnable() {
@Override
public void run() {
test.decrease();
}
}).start();
}
}
public synchronized void increase() {
try {
while(num != 0) {
wait();
System.out.println("increase wait 完毕");
}
num++;
System.out.println(num);
notifyAll();
System.out.println("increase notify");
Thread.sleep(new Random().nextInt(2000));
System.out.println("increase sleep完毕");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized void decrease() {
try {
while (num == 0) {
wait();
System.out.println("decrease wait 完毕");
}
num--;
System.out.println(num);
notifyAll();
System.out.println("decrease notify");
Thread.sleep(new Random().nextInt(2000));
System.out.println("decrease sleep完毕");
} catch (InterruptedException e) {
e.printStackTrace();
}
}

}

多个线程对同一变量加减（五个加，五个减），顺序不定，当变量值等于0时，减线程等待，当变量大于0时，加线程等待，以此达到变量值始终介于0和1之间