plume

Class ClassFileVersion

java.lang.Object

plume.ClassFileVersion

public final class ClassFileVersion
extends java.lang.Object

Given a list of .class files, print the class file version and also the JDK/JRE version required to run it. A .jar file can also be supplied, in which case each .class file within it is processed. Example use:

  java ClassFileVersion MyClass.class

Supplying the "-min JDKVER" argument suppresses output except for .class files that require at least that JDK version. For instance, to list all the .class/.jar files that require JDK 6 or later, in this or any subdirectory, run

find . \( -name '*.class' -o -name '*.jar' \) -print | xargs java ClassFileVersion -min 6
 

Method Summary

Modifier and Type	Method and Description
static void	main(java.lang.String[] args) Main method for the ClassFileVersion program.
static void	processClassFile(java.lang.String filename, java.io.InputStream is) Print, to standard out, the version number for the class file found in is.
static double[]	versionNumbers(java.io.InputStream is) Return an array of the major vernios, minor version, and JDK version of the class read from the input stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

Main method for the ClassFileVersion program.

Parameters:

args - command-line arguments

Throws:

java.io.IOException - if a file cannot be read

processClassFile

public static void processClassFile(java.lang.String filename,
                                    java.io.InputStream is)

Print, to standard out, the version number for the class file found in is.

Parameters:

filename - file name to appear in printed messages

is - input stream from which to read classfile bytes to process

versionNumbers

public static double[] versionNumbers(java.io.InputStream is)

Return an array of the major vernios, minor version, and JDK version of the class read from the input stream. Return null if there is an error or the input isn't a class file.

Parameters:

is - input stream from which to read a class

Returns:

array of three version numbers