code: public void insertCode() throws IOException, ParseException {
          CompilationUnit cuResult = JavaParser.parse(baseFile);
          if (cuResult.getImports() != null) {
              List<ImportDeclaration> importsFromBaseFile = cuResult.getImports();
              for (ImportDeclaration eachImport : importsFromExtendedFile) {
                  if (!importAlreadyPresent(importsFromBaseFile, eachImport)) {
                      importsFromBaseFile.add(eachImport);
                  }
              }
              cuResult.setImports(importsFromBaseFile);
          }
  
          String code = cuResult.toString();
  
          BufferedWriter b = new BufferedWriter(new FileWriter(baseFile));
          b.write(code);
          b.close();
      }
docs: This method will add methods, fields and import statement to existing java file
  
  @throws IOException
  @throws ParseException