I am currently working on a J2ME polish application, just enhancing it. I am finding difficulties to get the exact version of the jar file. Is there any way to find the version of the jar file for the imports done in the class? I mean if you have some thing, import x.y.z; can we know the version of the jar x.y package belongs to?

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14 Answers

Decompress the JAR file and look for the manifest file (META-INF\MANIFEST.MF). The manifest file of JAR file might contain a version number (but not always a version is specified).

9

You need to unzip it and check its META-INF/MANIFEST.MF file, e.g.

unzip -p file.jar | head

or more specific:

unzip -p file.jar META-INF/MANIFEST.MF

Just to expand on the answers above, inside the META-INF/MANIFEST.MF file in the JAR, you will likely see a line: Manifest-Version: 1.0 ← This is NOT the jar versions number!

You need to look for Implementation-Version which, if present, is a free-text string so entirely up to the JAR's author as to what you'll find in there. See also Oracle docs and Package Version specificaion

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Just to complete the above answer.

Manifest file is located inside jar at META-INF\MANIFEST.MF path.

You can examine jar's contents in any archiver that supports zip.

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Each jar version has a unique checksum. You can calculate the checksum for you jar (that had no version info) and compare it with the different versions of the jar. We can also search a jar using checksum.

Refer this Question to calculate checksum:What is the best way to calculate a checksum for a file that is on my machine?

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Basically you should use the java.lang.Package class which use the classloader to give you informations about your classes.

example:

String.class.getPackage().getImplementationVersion();
Package.getPackage(this).getImplementationVersion();
Package.getPackage("java.lang.String").getImplementationVersion();

I think logback is known to use this feature to trace the JAR name/version of each class in its produced stacktraces.

see also

Thought I would give a more recent answer as this question still comes up pretty high on searches.

Checking CLi JAR Version:

Run the following on the CLi jar file:

unzip -p jenkins-cli.jar META-INF/MANIFEST.MF

Example Output:

Manifest-Version: 1.0
Built-By: kohsuke
Jenkins-CLI-Version: 2.210 <--- Jenkins CLI Version
Created-By: Apache Maven 3.6.1
Build-Jdk: 1.8.0_144
Main-Class: hudson.cli.CLI

The CLi version is listed above.

To get the Server Version, run the following:

java -jar ./jenkins-cli.jar -s -auth <email>@<domain>.com:<API Token> version

(the above will vary based on your implementation of authentication, please change accordingly)

Example Output:

Dec 23, 2019 4:42:55 PM org.apache.sshd.common.util.security.AbstractSecurityProviderRegistrar getOrCreateProvider
INFO: getOrCreateProvider(EdDSA) created instance of net.i2p.crypto.eddsa.EdDSASecurityProvider
2.210 <-- Jenkins Server Version

This simple program will list all the cases for version of jar namely

• Version found in Manifest file
• No version found in Manifest and even from jar name

• Manifest file not found

  Map<String, String> jarsWithVersionFound = new LinkedHashMap<String, String>();
  List<String> jarsWithNoManifest = new LinkedList<String>();
  List<String> jarsWithNoVersionFound = new LinkedList<String>();
  //loop through the files in lib folder
  //pick a jar one by one and getVersion()
  //print in console..save to file(?)..maybe later
  File[] files = new File("path_to_jar_folder").listFiles();
  for(File file : files)
  { String fileName = file.getName(); try { String jarVersion = new Jar(file).getVersion(); if(jarVersion == null) jarsWithNoVersionFound.add(fileName); else jarsWithVersionFound.put(fileName, jarVersion); } catch(Exception ex) { jarsWithNoManifest.add(fileName); }
  }
  System.out.println("******* JARs with versions found *******");
  for(Entry<String, String> jarName : jarsWithVersionFound.entrySet()) System.out.println(jarName.getKey() + " : " + jarName.getValue());
  System.out.println("\n \n ******* JARs with no versions found *******");
  for(String jarName : jarsWithNoVersionFound) System.out.println(jarName);
  System.out.println("\n \n ******* JARs with no manifest found *******");
  for(String jarName : jarsWithNoManifest) System.out.println(jarName);

It uses the javaxt-core jar which can be downloaded from

2

I'm late this but you can try the following two methods

using these needed classes

import java.util.jar.Attributes;
import java.util.jar.Manifest;

These methods let me access the jar attributes. I like being backwards compatible and use the latest. So I used this

public Attributes detectClassBuildInfoAttributes(Class sourceClass) throws MalformedURLException, IOException { String className = sourceClass.getSimpleName() + ".class"; String classPath = sourceClass.getResource(className).toString(); if (!classPath.startsWith("jar")) { // Class not from JAR return null; } String manifestPath = classPath.substring(0, classPath.lastIndexOf("!") + 1) + "/META-INF/MANIFEST.MF"; Manifest manifest = new Manifest(new URL(manifestPath).openStream()); return manifest.getEntries().get("Build-Info");
}
public String retrieveClassInfoAttribute(Class sourceClass, String attributeName) throws MalformedURLException, IOException { Attributes version_attr = detectClassBuildInfoAttributes(sourceClass); String attribute = version_attr.getValue(attributeName); return attribute;
}

This works well when you are using maven and need pom details for known classes. Hope this helps.

For Linux, try following:

find . -name "YOUR_JAR_FILE.jar" -exec zipgrep "Implementation-Version:" '{}' \;|awk -F ': ' '{print $2}'

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If you have winrar, open the jar with winrar, double-click to open folder META-INF. Extract MANIFEST.MF and CHANGES files to any location (say desktop).

Open the extracted files in a text editor: You will see Implementation-Version or release version.

You can filter version from the MANIFEST file using

unzip -p my.jar META-INF/MANIFEST.MF | grep 'Bundle-Version'

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Just rename the extension with .zip instead of .jar. Then go to META-INF/MANIFEST.MF and open the MANIFEST.MF file with notepad. You can find the implementation version there.

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It can be checked with a command java -jar jarname

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