Thread嵌套Thread

public class Test1 {
private static Thread t4;
static Thread t1 = new Thread(){
@Override
public void run(){
System.out.println("1");
}
};
static Thread t2 = new Thread(){
@Override
public void run(){
try {
t4 = new Thread(){
@SuppressWarnings("static-access")
@Override
public void run(){
try {
t4.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("4");
}
};
t4.start();
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("2");
}
};
public static void main(String[] args){
t2.start();
try {
t2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
t1.start();

}
}