title: change compile version of existing jar file in java
body: <p>I have bccapi-1.2.0.jar file which i want to run on linux server but it could not run because of its compile version. </p>
  
  <p>Compile version of jar file is jdk1.7 which i downloaded from URL: <a href="http://www.antepedia.com/detail/p/bccapi.html" rel="nofollow noreferrer">http://www.antepedia.com/detail/p/bccapi.html</a> </p>
  
  <p>Server's jdk is jdk1.5. So how can i recompile existing jar with jdk1.5 environment.
  When i am trying to run that it give error like that  </p>
  
  <blockquote>
    <p>java.lang.UnsupportedClassVersionError: Bad version number in .class
    file (unable to load class com.lambdaworks.crypto.SCryptUtil)
      org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:2858)
      org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:1159)
      org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1647)
      org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
      java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
      com.elitecore.activation.utilities.CryptUtilities.validateScryptPassword(CryptUtilities.java:135)
      inventory.Application.CUsers.getUserBeanByNameandPassword(CUsers.java:131)
      inventory.modes.ChkLogin.process(ChkLogin.java:55)
      inventory.servlet.UserServlet.doPost(UserServlet.java:62)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:643)</p>
  </blockquote>
  
  <p>This error occured when i am executing jar file on server.</p>
  
  <p><img src="https://i.stack.imgur.com/Pwurt.png" alt="This error occured when i am executing jar file on server">  </p>