Which And What Utilities

This essay does not describe an existing computer program, just one that should exist. This essay is about a suggested student project in Java programming. This essay gives a rough overview of how it might work. I have no source, object, specifications, file layouts or anything else useful to implementing this project. Everything I have to say to help you with this project is written below. I am not prepared to help you implement it; I have too many other projects of my own.

I do contract work for a living, which could include writing a program such as this. However, I don’t do people’s homework for them. That just robs them of an education.

You have my full permission to implement this project in any way you please and to keep all the profits from your endeavor.

This is similar to the PathTool project. These are some simple command line diagnostic tools:

which p.exe This searches the current path for the given executable file (fully qualified). It then displays all the occurences it finds, i.e. the fully qualified directories where it found that file, and sets the return code to the number of instances it finds.
which X.Y.P.class does the same thing, but search the classpath, including any jars in the classpath for instances of X.Y.P.class. You can use simple wildcards such as *.P.class to look for the class in any package. *.*.class would get you a list of all classes available on the classpath. The search is case insensistive, but since Java is case sensitive, only case sensitive matches appear in the count. Case mismatches are highlighted.
which getSize.method does the same thing, but search the classpath, including any jars in the classpath for instances of classes containing a getSize method. More elaborate versions would let you specify a more specific method signature. The utility should take a -cp option on the command line, defaulting to the SET classpath if there is none.
what C:\temp\ThisFile.class Displays the fully qualified classname of the class corresponding to the file.
what C:\temp\ThisJar.jar Displays the fully qualified classnames of all the classes in the jar.

Your what utility might be expanded to tell you interesting facts about other types of file. Eg.

exe : what OS/memory model is it for. Look for file signatures for various Windows, Linux, etc executable file formats. You can look for bytes without needing platform-specific code.
txt: word and line count.
doc: which version of MS Word created it.

Ideally this is runs on any platform unmodified, though if you find yourself needing JNI, try at least to support both Windows and Linux, using JWS to select the correct native class.

Interface Finder: find classes on classpath implementing a given inteface
jar
jar verifier Project
JarCheck
JarLook
Java class finder: searches local disk jars for classes
Java Jar Catalog Project
Path and Classpath tool project

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