Re: Quiz Question: Classpath Search Rules & JARs

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.help

Date:

Thu, 3 Feb 2011 13:00:30 -0800 (PST)

Message-ID:

<0a2da252-4288-461d-a2bd-8c742fe01df9@q2g2000pre.googlegroups.com>

Steve wrote:

Hi. I took a quiz question in a book concerning the use of classpath
and JARs. The answers given by the book seem inconsistent with the
rules and with other answers in the same question. I think there is
a special rules for JARs and class paths that I missed?

Yep.

Okay.

The current directory is "test" which has MyJar.jar in it.

test -|
        MyJar.jar
        MyProgram.java
        |
        | ____ myApp ( a subdirectory )|
                                    =

|__ Foo.java

MyProgram.java calls Foo.java. It is dependent on Foo.java and must
find it to run

The book said that these two commands will compile and run
MyProgram.java if the current directory is "test"

javac -classpath MyJar.jar MyProgram.java
java MyProgram

1. I don't understand how "java" finds the MyProgram class since the
book says that the JVM will not search the current directory for class
files unless it is listed in the classpath.

The default CLASSPATH is ".".

This is in the documentation.

2. I don't understand how javaC [sic] is finding MyJar.jar. In an =

earlier

example the book stated the compiler will not search the current
directory if the classpath is relative and starts with the current
directory. Is the rule different for JARs? WIll the compiler searc=

the current directory for JAR if the JAR is listed in a relative ( and
correct for the current dir ) classpath?

You told it where to find the JAR in your command line!

With the "-classpath" option!

Which specifies the classpath!

That's not a different rule, that's the rule. You specified the
classpath, that's how "javac" knew where the classpath was.

--
Lew