How to call repository service in main class and use main arguments? - spring

Question

in my spring boot application I'm using main arguments to pass variables and need to call a method to save an object into database based on some code in main class.
I'm using main class like that:
#SpringBootApplication
public class MainClass {
#Autowired
private RecordingService recordingService;
public MainClass(String arg1, String arg2) {
this.setArg1(arg1);
this.setArg2(arg2);
}
public static void main(String args[]) {
String ip = null;
String op = null;
if (args != null & args.length > 0) {
for (int i = 0; i < args.length; i++) {
if (args[i].equalsIgnoreCase("-ip")) {
ip = args[i + 1].trim();
} else if (args[i].equalsIgnoreCase("-op")) {
op = args[i + 1].trim();
}
i++;
}
}
if (ip == null || op == null) {
System.out.println("Invalid input or output path.");
} else {
MainClass reader = new MainClass(ip, op);
Recording recording = new Recording();
.
.
some code...
.
.
this.recordingService.insertIntoDB(recording);
}
}
}
}
And this is service class:
#Service
public class RecordingService {
#Autowired
private RecordingRepository recordingRepository;
public RecordingService() {
}
public void insertToDatabase(Recording recording) {
try {
Recording recording = new Recording();
this.recordingRepository.save(recording);
} catch (Exception e) {
e.printStackTrace();
}
}
}
When I run this code I get NullPointerException, What is the mistake in this code?

Answer 1

You are starting the main method without Spring so Spring won't create RecordingService. It can be changed using CommandLineRunner:
#SpringBootApplication
public class MainClass implements CommandLineRunner {
#Autowired
private RecordingService recordingService;
public static void main(String[] args) {
SpringApplication.run(MainClass.class, args);
}
#Override
public void run(String... args) {
//your main code here
}
}