how to check the jdk version used to compile a class file

Question

Possible Duplicate    Tool to read and display Java  class versions       I m trying to debug a       Bad version number in  class file     error in java  is there a way for me to check which version the  class files are   I m using JRE1 5 0 6  but my JDK is version 1 6 0 13   I m compiling with compatibility mode set to 1 5 in eclipse which I thought would work

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Does the -verbose flag to your java command yield any useful info   If not  maybe java -X reveals something specific to your version that might help

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You can try jclasslib   https   github com ingokegel jclasslib  It s nice that it can associate itself with   class extension

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You re looking for this on the command line  for a class called MyClass    On Unix Linux   javap -verbose MyClass   grep  major    On Windows   javap -verbose MyClass   findstr  major    You want the major version from the results  Here are some example values    Java 1 2 uses major version 46 Java 1 3 uses major version 47 Java 1 4 uses major version 48 Java 5 uses major version 49 Java 6 uses major version 50 Java 7 uses major version 51 Java 8 uses major version 52 Java 9 uses major version 53 Java 10 uses major version 54 Java 11 uses major version 55

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Btw  the reason that you re having trouble is that the java compiler recognizes two version flags  There is -source 1 5  which assumes java 1 5 level source code  and -target 1 5  which will emit java 1 5 compatible class files  You ll probably want to use both of these switches  but you definitely need -target 1 5  try double checking that eclipse is doing the right thing

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Free JarCheck tool here

[java] how to check the jdk version used to compile a .class file

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