Mysterious newInstance method

Posted by songsungkyun on Stack Overflow See other posts from Stack Overflow or by songsungkyun
Published on 2010-05-07T09:16:26Z Indexed on 2010/05/07 9:18 UTC
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First I show some code.

library: axis.jar, dom4j.jar jdk1.5, windowsXP


T.java

import java.io.StringWriter;

import org.apache.axis.utils.StringUtils;
import org.dom4j.DocumentHelper;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;


public class T {
public T() {
    System.out.println("constructor");
}

public void test() {
    System.out.println(StringUtils.unescapeNumericChar("1"));
}

public String getPrettyXML(String xml) throws Exception {
    System.out.println("getPrettyXML");
    StringWriter sw = new StringWriter();
    XMLWriter writer = null;
    try {
        OutputFormat format = OutputFormat.createPrettyPrint();
        org.dom4j.Document document = DocumentHelper.parseText(xml);
        writer = new XMLWriter(sw, format);
        writer.write(document);
    } catch (Exception e) {
        throw e;
    } finally {
        if (writer != null) {
            try {
                writer.close();
            } catch (Exception e) {
            }
        }
    }
    return sw.toString();
}

public void a() {
    System.out.println("a");
}

public static void main(String[] args) {
    new T().test();
}

}


T2.java

public class T2 {
public static void main(String[] args) throws Exception {
    System.out.println("T2");
    T t = (T) Class.forName("T").newInstance();     
}
}

Ok, here we go... run as (Of course, I'm run at the directory where T.class, T1.class is)

java T2

as you can see, not exist class path.

==console==
T2
constructor

OK... Now delete

throw e

line at the catch block on the "getPrettyXML" method of T.

Ok, here we go.. run one more time without classpath

java T2

You can see below...

==console==
T2
Exception in thread "main" java.lang.NoClassDefFoundError: org/dom4j/io/OutputFormat
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at T2.main(T2.java:5)

I know that it's not very important for my life or your life. But it's so mysterisou to me, and my all curiosity. thanks.. ^^

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