Name: akC45999 Date: 02/16/98



The JVM spec 2.15.14 The Classes Exception and RuntimeException reads:

A Java Virtual Machine throws ... LinkageError when loading ... error occurs.
The Loading process is described in (2.16.2). The errors ClassFormatError,
ClassCircularityError, and NoClassDefFoundError are described there.

Note that ClassNotFoundException is not in this list.
But VM throws ClassNotFoundException when an instruction which may cause
class resolution (such as anewarray, checkcast, getstatic, invokespecial,
and so on) causes loading unexistent class and current
classloader is user-defined one.

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Name: akC45999 Date: 02/17/98



This example illustrates the bug.
Place file Example.java in a working directory.
Make there a directory named "store" and place file TestClass.java in it.
Compile files in their directories.
In the working directory, run java Example, just to test installation.
You must get message:
fantom.field==123

Remove file store/fantom.class and rerun java Example.

You'll get the message:
TestClass: java.lang.ClassNotFoundException: fantom

which is thrown by getstatic instruction.

================================ Example.java
import java.io.*;

class Example extends ClassLoader {
    File store;
    Example(File store) {
        this.store=store;
    }

    void debug(String msg) {
 // System.out.println(msg);
    }

    byte readClass(String className)[] {
        byte result[];
        try {
            FileInputStream fi
                = new FileInputStream(new File(store, className+".class"));
            result = new byte[fi.available()];
            fi.read(result);
            debug(" >> readClass("+className+") OK");
            return result;
        } catch (Exception e) {
            debug(" >> readClass("+className+"):"+e);
            return null;
        }
    }

    public Class loadClass(String className, boolean resolve) throws ClassNotFoundException {
       Class result;
        byte classData[];

        debug("> Load class : "+className);

        /* Try to load it from our repository */
        classData = readClass(className);
        if (classData == null) {
         /* Check with the primordial class loader */
            result = super.findSystemClass(className);
            debug(" >> returning class in CLASSPATH.:"+result);
            return result;
        }

        /* Define it (parse the class file) */
        result = defineClass(classData, 0, classData.length);
        if (result == null) {
            throw new ClassFormatError();
        }

        debug(" >> Returning newly loaded class:"+className);
        return result;
    }

    public static void main(String args[]) {
        File store=new File("store");
        Example sc = new Example(store);
        try {
            (sc.loadClass("TestClass")).newInstance();
        } catch (Throwable e) {
            System.out.println("Example: "+e);
        }
    }
}
================================ end Example.java
================================ TestClass.java
class fantom {
    static int field=123;
}

public class TestClass {
    public TestClass() {
        try {
            System.out.println("fantom.field=="+fantom.field);
        } catch (Throwable e) {
            System.out.println("TestClass: "+e);
        }
    }
}

================================ end TestClass.java

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Name: akC45999 Date: 02/17/98



This bug also causes failures of the following JCK tests
while they are run under JavaOS (see bug 4073835):

vm/constantpool/ClassInterf/ClassInterf009/ClassInterf00901
vm/instr/anewarray/anewarray008/anewarray00801
vm/instr/checkcast/checkcast010/checkcast01001
vm/instr/invokestatic/invokestatic008/invokestatic00801
vm/instr/putstatic/putstatic009/putstatic00903
vm/instr/getstatic/getstatic008/getstatic00803

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