I am having difficulty understanding the behavior of inner class threads.
I have this simple test program.
public class Test {
private static Random rand = new Random(System.currentTimeMillis());
public class TestThread extends Thread {
@Override
public void start() {
System.out.println("in start " + Thread.currentThread().getName());
try {
Thread.sleep(rand.nextInt(5000));
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static void main(String[] args){
System.out.println(Thread.currentThread().getName());
for(int i = 0; i < 5; ++i){
new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(rand.nextInt(5000));
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName());
}
}).start();
}
System.out.println("new run");
Test test = new Test();
for(int i = 0; i < 5; ++i){
(test. new TestThread()).start();
}
}
}
When the first for loop runs, the threads behaves as I expected. Total of 6 threads, main, thread-0, thread-1, thread-2, thread-3, and thread-4. Thread 0 - 4 are printed out of order as I expected.
The result for second for loop has me confused.
system.out.println("in start " + Thread.currentThread().getName());
It always prints out "main," and the threads are executed sequentially. Why is the execution of the inner class thread carried out by the main thread?
Thanks!
