（1）使用join()方法
在多个线程的执行过程中，若需要对于线程之间的执行顺序有要求的话，可以使用Thread类的join()方法，简单地对于join线程进行解释的话就是：
调用线程要等待join线程执行完成之后才可以继续向下执行
比如我们需要让主线程得到一个Thread1的输出值，这样子就得让Thread1执行完成之后，主线程的内容再继续执行：
package thread.test;
public class JoinFunctionTest {
public static void main(String[] args) throws InterruptedException {
// 测试join()
Thread thread1 = new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("Thread1执行");
}
});
thread1.start();
thread1.join();
System.out.println("等thread1执行完再执行主线程");
}
}
package thread.test;
public class JoinFunctionTest {
public static void main(String[] args) throws InterruptedException {
// 测试join()
final Thread thread1 = new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("Thread1执行");
}
});
final Thread thread2 = new Thread(new Runnable() {
@Override
public void run() {
try {
thread1.join();
System.out.println("Thread2执行");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
Thread thread3 = new Thread(new Runnable() {
@Override
public void run() {
try {
thread2.join();
System.out.println("Thread3执行");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
System.out.println("开始：");
System.out.println("Thread1上线...");
thread3.start();
System.out.println("Thread2上线...");
thread1.start();
System.out.println("Thread3上线...");
thread2.start();
}
}
（2）使用wait()方法和notify()方法
package thread.test;
/**
*
* wait():是Object的方法，作用是让当前线程进入等待状态，同时，wait()也会让当前线程释放它所持有的锁。“直到其他线程调用此对象的
* notify() 方法或 notifyAll() 方法”，当前线程被唤醒(进入“就绪状态”)
*
* notify()和notifyAll():是Object的方法，作用则是唤醒当前对象上的等待线程；notify()是唤醒单个线程，而notifyAll()是唤醒所有的线程。
*
* wait(long timeout):让当前线程处于“等待(阻塞)状态”，“直到其他线程调用此对象的notify()方法或 notifyAll()
* 方法，或者超过指定的时间量”，当前线程被唤醒(进入“就绪状态”)。
*
* 应用场景：Java实现生产者消费者的方式。
*/
public class WaitTest {
private static Object myLock1 = new Object();
private static Object myLock2 = new Object();
/**
* 为什么要加这两个标识状态? 如果没有状态标识，当t1已经运行完了t2才运行，t2在等待t1唤醒导致t2永远处于等待状态
*/
private static Boolean t1Run = false;
private static Boolean t2Run = false;
public static void main(String[] args) {
final Thread thread1 = new Thread(new Runnable() {
@Override
public void run() {
synchronized (myLock1) {
System.out.println("Thread1开始执行...");
t1Run = true;
myLock1.notify();
}
}
});
final Thread thread2 = new Thread(new Runnable() {
@Override
public void run() {
synchronized (myLock1) {
try {
if (!t1Run) {
System.out.println("Thread2休息会...");
myLock1.wait();
}
synchronized (myLock2) {
System.out.println("Thread2开始执行..");
myLock2.notify();
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
});
Thread thread3 = new Thread(new Runnable() {
@Override
public void run() {
synchronized (myLock2) {
try {
if (!t2Run) {
System.out.println("Thread3先休息会...");
myLock2.wait();
}
System.out.println("Thread3开始执行..");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
});
System.out.println("开始：");
System.out.println("Thread1来了...");
thread3.start();
System.out.println("Thread2来了...");
thread1.start();
System.out.println("Thread3来了...");
thread2.start();
}
}
