code: public final void findCallingMethodsInJar(final File file) throws IOException {
  
          try (final JarFile jarFile = new JarFile(file)) {
  
              final Enumeration<JarEntry> entries = jarFile.entries();
  
              while (entries.hasMoreElements()) {
                  final JarEntry entry = entries.nextElement();
  
                  if (entry.getName().endsWith(".class")) {
                      final InputStream in = new BufferedInputStream(jarFile.getInputStream(entry), 1024);
                      try {
                          new ClassReader(in).accept(cv, 0);
                      } finally {
                          in.close();
                      }
                  }
              }
  
          }
      }
docs: Locate method calls in classes of a JAR file.
  
  @param file
  File to search.
  
  @throws IOException
  Error reading the file.