在多线程中有多种方法让线程按特定顺序执行，可以用线程类的join()方法在一个线程中启动另一个线程，另外一个线程完成该线程继续执行。
为了确保三个线程的顺序你应该先启动最后一个(T3调用T2，T2调用T1)，这样T1就会先完成而T3最后完成。实际上先启动三个线程中哪一个都行，因为在每个线程的run方法中用join方法限定了三个线程的执行顺序。
实例一public static void main(String[] args) {
final Thread t1 = new Thread(() -> System.out.println("A"));
final Thread t2 = new Thread(() -> {
try {
// 引用t1线程，等待t1线程执行完
t1.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("B");
});
Thread t3 = new Thread(() -> {
try {
// 引用t2线程，等待t2线程执行完
t2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("C");
});
t3.start();//这里三个线程的启动顺序可以任意
t2.start();
t1.start();
}
t1
t2
t3
实例二public static class T1 implements Runnable {
@Override
public void run() {
new Thread(new T2()).start();
System.out.println("A");
}
}
public static class T2 implements Runnable {
@Override
public void run() {
new Thread(new T3()).start();
System.out.println("B");
}
}
public static class T3 implements Runnable {
@Override
public void run() {
System.out.println("C");
}
}
public static void main(String[] args) {
new Thread(new T1()).start();
}
实例三public static class T1 extends Thread {
@Override
public void run() {
System.out.println("A");
}
}
public static class T2 extends Thread {
@Override
public void run() {
System.out.println("B");
}
}
public static class T3 extends Thread {
@Override
public void run() {
System.out.println("C");
}
}
public static void main(String[] args) throws Exception{
T1 t1 = new T1();
T2 t2 = new T2();
T3 t3 = new T3();
t1.start();
t1.join();
t2.start();
t2.join();
t3.start();
t3.join();
}
