| type | layout | category | title |
|---|---|---|---|
doc |
reference |
Syntax |
Packages and Imports |
A source file may start with a package declaration:
``` kotlin
package foo.bar
fun baz() { ... } class Goo { ... }
// ...
</div>
All the contents (such as classes and functions) of the source file are contained by the package declared.
So, in the example above, the full name of `baz()` is `foo.bar.baz`, and the full name of `Goo` is `foo.bar.Goo`.
If the package is not specified, the contents of such a file belong to "default" package that has no name.
## Default Imports
A number of packages are imported into every Kotlin file by default:
- [kotlin.*](/api/latest/jvm/stdlib/kotlin/index.html)
- [kotlin.annotation.*](/api/latest/jvm/stdlib/kotlin.annotation/index.html)
- [kotlin.collections.*](/api/latest/jvm/stdlib/kotlin.collections/index.html)
- [kotlin.comparisons.*](/api/latest/jvm/stdlib/kotlin.comparisons/index.html) (since 1.1)
- [kotlin.io.*](/api/latest/jvm/stdlib/kotlin.io/index.html)
- [kotlin.ranges.*](/api/latest/jvm/stdlib/kotlin.ranges/index.html)
- [kotlin.sequences.*](/api/latest/jvm/stdlib/kotlin.sequences/index.html)
- [kotlin.text.*](/api/latest/jvm/stdlib/kotlin.text/index.html)
Additional packages are imported depending on the target platform:
- JVM:
- java.lang.*
- [kotlin.jvm.*](/api/latest/jvm/stdlib/kotlin.jvm/index.html)
- JS:
- [kotlin.js.*](/api/latest/jvm/stdlib/kotlin.js/index.html)
## Imports
Apart from the default imports, each file may contain its own import directives.
Syntax for imports is described in the [grammar](grammar.html#import).
We can import either a single name, e.g.
<div class="sample" markdown="1" theme="idea" data-highlight-only>
``` kotlin
import foo.Bar // Bar is now accessible without qualification
or all the accessible contents of a scope (package, class, object etc):
``` kotlin
import foo.* // everything in 'foo' becomes accessible
```
If there is a name clash, we can disambiguate by using as{: .keyword } keyword to locally rename the clashing entity:
``` kotlin
import foo.Bar // Bar is accessible
import bar.Bar as bBar // bBar stands for 'bar.Bar'
```
The import keyword is not restricted to importing classes; you can also use it to import other declarations:
- top-level functions and properties;
- functions and properties declared in object declarations;
- enum constants.
Unlike Java, Kotlin does not have a separate "import static" syntax; all of these declarations are imported using the regular import keyword.
If a top-level declaration is marked private{: .keyword }, it is private to the file it's declared in (see Visibility Modifiers).