有三个线程T1 T2 T3，如何保证他们按顺序执行-转载

public class Test {

// 1.现在有T1、T2、T3三个线程，你怎样保证T2在T1执行完后执行，T3在T2执行完后执行


public static void main(String[] args) {

final Thread t1 = new Thread(new Runnable() {

@Override
public void run() {
System.out.println("t1");
}
});
final Thread t2 = new Thread(new Runnable() {

@Override
public void run() {
try {
//引用t1线程，等待t1线程执行完
t1.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("t2");
}
});
Thread t3 = new Thread(new Runnable() {

@Override
public void run() {
try {
//引用t2线程，等待t2线程执行完
t2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("t3");
}
});
t3.start();
t2.start();
t1.start();//这三个线程启动没有先后顺序的
}
}