Re: I need to know if a java class import a package

From:
=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>
Newsgroups:
comp.lang.java.programmer
Date:
Sat, 28 Apr 2007 22:43:05 -0400
Message-ID:
<463405fc$0$90275$14726298@news.sunsite.dk>
Daniel wrote:

I need that some users fill with code in page to solve a task, this
task involves the sorting of an array of integers, this could be
easily solved with Collections.sort, but I gave them as a
precondition, they couldn't use the Collections class (because I want
to test if they can iterate an order an array by themselves).
To correct this tasks, I have a Junit class that test against the
submitted code, so I was searching for some mechanism that could help
me with this.


You need to get the classloader used to tell you.

Here are a starting point:

import java.net.URL;
import java.net.URLClassLoader;

public class TraceClassLoader extends URLClassLoader {
     public TraceClassLoader(String cp) throws Exception {
         super(new URL[] { new URL(cp) });
     }
     protected Class<?> loadClass(String name, boolean resolve) throws
ClassNotFoundException {
         System.out.println(name);
         return super.loadClass(name, resolve);
     }
     public static void main(String[] args) throws Exception {
         Class.forName(args[0], true, new
TraceClassLoader(args[1])).getMethod("main", new Class[] {
String[].class }).invoke(null, new Object[] { new String[0] });
     }
}

import java.util.*;

public class Foobar {
    public static void main(String[] args) throws Exception {
        List lst = new ArrayList();
        lst.add("CCC");
        lst.add("BB");
        lst.add("A");
        for(int i = 0; i < lst.size(); i++) {
            System.out.println(lst.get(i));
        }
        Collections.sort(lst);
        for(int i = 0; i < lst.size(); i++) {
            System.out.println(lst.get(i));
        }
    }
}

java TraceClassLoader Foobar file:/C:/

Foobar
java.lang.Object
java.util.List
java.lang.String
java.lang.Exception
java.util.ArrayList
java.lang.System
java.io.PrintStream
CCC
BB
A
java.util.Collections
A
BB
CCC

Arne

PS: It is important that Foobar.class is not in the classpath where
     TraceClassLoader is running.

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