# Spring Tutorial

**URL:** <https://discuss.kotlinlang.org/t/spring-tutorial/334>\
**Category:** Uncategorized\
**Created:** [February 12, 2015, 2:20pm UTC](https://discuss.kotlinlang.org/t/spring-tutorial/334 "2015-02-12T14:20:14Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![evacchi](https://avatars.discourse-cdn.com/v4/letter/e/bc8723/32.png) [@evacchi](https://discuss.kotlinlang.org/u/evacchi)\
**Post date:** [February 12, 2015, 2:20pm UTC](https://discuss.kotlinlang.org/t/spring-tutorial/334/1 "2015-02-12T14:20:14Z")

</div>

I have played a bit with the Spring tutorial, mainly because I find the Application class definition/main method quite cumbersome and wanted to see if there was a better way to do that. I do understand all of it, so it is clear to me what each element does. It's just that it looks much more busy than I thought it should be.

Compare:

&nbsp;

```kotlin
ComponentScan
EnableAutoConfiguration
public class Application {
    class object {
        platformStatic public fun main(args: Array<String>) {
           SpringApplication.run(javaClass<Application>(), *args)
        }
    }
}
```

vs. Java's

```kotlin
@ComponentScan
@EnableAutoConfiguration
public class Application {
    static public void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}
```

I mean, this is terrible. Java's version is shorter and, I may dare to say, even prettier to look at. This is unacceptable to me :-) Kotlin is supposed to look much nicer than Java (it usually does!)

So, here are my attemps (which all failed horribly):

1. There is no need for the **main()** method to be inside the Application class. That is just a Spring convention. So, let’s move it outside:

```kotlin

```

`
but then gradle fails with:
`

```kotlin
Execution failed for task ':findMainClass'.
> Unable to find a single main class from the following candidates [_DefaultPackage, _DefaultPackage$Application$e0b08dc9]
 
```

So, apparently there's something wrong with using the default package.

1. Fine let’s move it to **com.example;** it’s better, anyway.

```kotlin
> Unable to find a single main class from the following candidates [com.example.ExamplePackage, com.example.ExamplePackage$Application$05fdfa5c]
```

Nope, it's not working. So, let's inspect the first class with **javap** It is in fact defining a main() static method which, in turn, invokes another static method inside **ExamplePackage$Application$05fdfa5c**

```kotlin
  public static final void main(java.lang.String[]);
    flags: ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    Code:tf8           Lorg/jetbrains/annotations/NotNull;
      stack=1, locals=1, args_size=1le/ExamplePackage$Application$05fdfa5c
         0: aload_0   #24           //  com/example/ExamplePackage$Application$05fdfa5c
         1: invokestatic  #27           // Method com/example/ExamplePackage$Application$05fdfa5c.main:([Ljava/lang/String;)V
 
```

```kotlin

```

`
so that is why :findMainClass gets confused.
`

`Now, I’m wondering: why are these two methods generated at all? Why do we have more than one main() method?`

`
thanks!
PS: the problem can be easily fixed by adding the following lines inside build.gradle
`

```kotlin
springBoot {
    mainClass = '_DefaultPackage'
}
```

or, in the case of the **com.example** package:

```kotlin
springBoot {
    mainClass = 'com.example.ExamplePackage'
}
```

---

<div class="post-metadata">

**Author:** ![MarioArias](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/marioarias/32/1488_2.png) [@MarioArias](https://discuss.kotlinlang.org/u/MarioArias)\
**Post date:** [February 12, 2015, 4:48pm UTC](https://discuss.kotlinlang.org/t/spring-tutorial/334/2 "2015-02-12T16:48:29Z")

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There is another way to do it, using the main class at package level

Check this example, is based on Kotlin M8 (before platformStatic support)

[https://github.com/MarioAriasC/gs-relational-data-access/tree/master/kotlin](https://github.com/MarioAriasC/gs-relational-data-access/tree/master/kotlin)

---

<div class="post-metadata">

**Author:** ![MarioArias](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/marioarias/32/1488_2.png) [@MarioArias](https://discuss.kotlinlang.org/u/MarioArias)\
**Post date:** [February 12, 2015, 4:57pm UTC](https://discuss.kotlinlang.org/t/spring-tutorial/334/3 "2015-02-12T16:57:08Z")

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This is probably closer to the thing that you want to achieve

[https://github.com/MarioAriasC/gs-rest-service/tree/master/kotlin](https://github.com/MarioAriasC/gs-rest-service/tree/master/kotlin)