最终的程序代码如下：
public class ThreadTest {
public static void main(String[] args) {
new ThreadTest().init();
}
public void init() {
final Business business = new Business();
new Thread(new Runnable() {
public void run() {
for (int i = 0; i < 50; i++) {
business.SubThread(i);
}
}
}).start();
for (int i = 0; i < 50; i++) {
business.MainThread(i);
}
}
private class Business {
boolean bShouldSub = true;// 这里相当于定义了控制该谁执行的一个信号灯
public synchronized void MainThread(int i) {
if (bShouldSub)
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
for (int j = 0; j < 5; j++) {
System.out.println(Thread.currentThread().getName() + ":i=" + i + ",j=" + j);
}
bShouldSub = true;
this.notify();
}
public synchronized void SubThread(int i) {
if (!bShouldSub)
try {
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
for (int j = 0; j < 10; j++) {
System.out.println(Thread.currentThread().getName() + ":i=" + i + ",j=" + j);
}
bShouldSub = false;
this.notify();
}
}
}
备注：不可能一上来就写出上面的完整代码，最初写出来的代码如下，问题在于两个线程的代码要参照同一个变量，即这两个线程的代码要共享数据，所以，把这两个线程的执行代码搬到同一个类中去：
package com.huawei.interview.lym;
public class ThreadTest {
private static boolean bShouldMain = false;
public static void main(String[] args) {
new Thread(new Runnable() {
public void run() {
for (int i = 0; i < 50; i++) {
synchronized (ThreadTest.class) {
if (bShouldMain) {
try {
ThreadTest.class.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
for (int j = 0; j < 10; j++) {
System.out.println(Thread.currentThread().getName() + "i=" + i + ",j=" + j);
}
bShouldMain = true;
ThreadTest.class.notify();
}
}
}
}).start();
for (int i = 0; i < 50; i++) {
synchronized (ThreadTest.class) {
if (!bShouldMain) {
try {
ThreadTest.class.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
for (int j = 0; j < 5; j++) {
System.out.println(Thread.currentThread().getName() + "i=" + i + ",j=" + j);
}
bShouldMain = false;
ThreadTest.class.notify();
}
}
}
}
下面使用jdk5中的并发库来实现的：
import java.util.concurrent.Executors;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.Condition;
public class ThreadTest {
private static Lock lock = new ReentrantLock();
private static Condition subThreadCondition = lock.newCondition();
private static boolean bBhouldSubThread = false;
public static void main(String[] args) {
ExecutorService threadPool = Executors.new FixedThreadPool(3);
threadPool.execute(new Runnable() {
public void run() {
for (int i = 0; i < 50; i++) {
lock.lock();
try {
if (!bBhouldSubThread)
subThreadCondition.await();
for (int j = 0; j < 10; j++) {
System.out.println(Thread.currentThread().getName() + ",j=" + j);
}
bBhouldSubThread = false;
subThreadCondition.signal();
} catch (Exception e) {
} finally {
lock.unlock();
}
}
}
});
threadPool.shutdown();
for (int i = 0; i < 50; i++) {
lock.lock();
try {
if (bBhouldSubThread)
subThreadCondition.await();
for (int j = 0; j < 10; j++) {
System.out.println(Thread.currentThread().getName() + ",j=" + j);
}
bBhouldSubThread = true;
subThreadCondition.signal();
} catch (Exception e) {
} finally {
lock.unlock();
}
}
}
}
