Question

Java 请帮帮忙,下面这个程序错在哪？

import org.omg.PortableServer.ThreadPolicyOperations;

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/

/**
*
* @author stud
*/
public class Java_2 extends Thread{

public static void main(String args[]) {
Hello h = new Hello();
//*********Found********
Thread t = Thread(h);
t.start();
}
}

//*********Found********
class Hello implements ThreadPolicy {

int i = 0;

public void run() {
while (true) {
System.out.println("Hello!");
if (i++ == 5) {
break;
}
}
}
}

Answer 1

有几个问题：
1. Thread t = Thread(h); 这行少了new
2. Hello要implement Runnable，才能放到Thread()里面（也就是上面第1点提到的那个行那种用法）
3. ThreadPolicy的很多其他method没有实现。我下面的代码加了，但是每个method里面没实际代码

下面程序运行结果为：
Hello!
Hello!
Hello!
Hello!
Hello!
Hello!

import org.omg.CORBA.Context;
import org.omg.CORBA.ContextList;
import org.omg.CORBA.DomainManager;
import org.omg.CORBA.ExceptionList;
import org.omg.CORBA.NVList;
import org.omg.CORBA.NamedValue;
import org.omg.CORBA.Object;
import org.omg.CORBA.Policy;
import org.omg.CORBA.Request;
import org.omg.CORBA.SetOverrideType;
import org.omg.PortableServer.ThreadPolicy;
import org.omg.PortableServer.ThreadPolicyValue;

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/

/**
*
* @author stud
*/
public class Java_2 extends Thread{

public static void main(String args[]) {
Hello h = new Hello();
//*********Found********
Thread t = new Thread(h);
t.start();
}
}

//*********Found********
class Hello implements ThreadPolicy, Runnable {

/**
*
*/
private static final long serialVersionUID = -112603238151033723L;
int i = 0;

public void run() {
while (true) {
System.out.println("Hello!");
if (i++ == 5) {
break;
}
}
}

public ThreadPolicyValue value() {
// TODO Auto-generated method stub
return null;
}

public Policy copy() {
// TODO Auto-generated method stub
return null;
}

public void destroy() {
// TODO Auto-generated method stub

}

public int policy_type() {
// TODO Auto-generated method stub
return 0;
}

public Request _create_request(Context arg0, String arg1, NVList arg2,
NamedValue arg3) {
// TODO Auto-generated method stub
return null;
}

public Request _create_request(Context arg0, String arg1, NVList arg2,
NamedValue arg3, ExceptionList arg4, ContextList arg5) {
// TODO Auto-generated method stub
return null;
}

public Object _duplicate() {
// TODO Auto-generated method stub
return null;
}

public DomainManager[] _get_domain_managers() {
// TODO Auto-generated method stub
return null;
}

public Object _get_interface_def() {
// TODO Auto-generated method stub
return null;
}

public Policy _get_policy(int arg0) {
// TODO Auto-generated method stub
return null;
}

public int _hash(int arg0) {
// TODO Auto-generated method stub
return 0;
}

public boolean _is_a(String arg0) {
// TODO Auto-generated method stub
return false;
}

public boolean _is_equivalent(Object arg0) {
// TODO Auto-generated method stub
return false;
}

public boolean _non_existent() {
// TODO Auto-generated method stub
return false;
}

public void _release() {
// TODO Auto-generated method stub

}

public Request _request(String arg0) {
// TODO Auto-generated method stub
return null;
}

public Object _set_policy_override(Policy[] arg0, SetOverrideType arg1) {
// TODO Auto-generated method stub
return null;
}
}

Answer 2

看你这个结构应该是想使用多线程的
但是你这里 用实现ThreadPolicy来完成多线程我就不明白你什么意思了

不妨将这段代码改成这样：
public static void main(String args[]) {
Hello h = new Hello();
Thread t = new Thread(h);
t.start();
}
}

class Hello implements Runnable {
int i = 0;
public void run() {
while (true) {
System.out.println("Hello!");
if (i++ == 5) {
break;
}
}
}

Answer 3

Thread t = Thread(h);要改成Thread t =new Thread(h);

然后在t.start();后面加上t.join();
不然主线程执行完t.start就结束了，程序也就随即结束了，等不到t线程输出