Hello everyone I have question about Kotlin and room kotlinlang #android

Yeah You are right. java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter author

How can I solve this one ?

gildor

01/25/2018, 8:29 AM

don’t use

!!

you can specify default value instead

Copy code

title = it.title ?: "Some default value"

!!

is unsafe operation, you should always try to avoid use of

!!

!!

means “I sure this value is not null, so allow me to use it” so if value actually

null

your code will throw exception

Alternatively you can make

News.author

nullable, so in this case just assign null

Nizzle94

01/25/2018, 8:32 AM

Wooow thank you bro. You saved my day. I used this one “title = it.title ?: “Some default value”"

gildor

01/25/2018, 8:33 AM

You should read this part of official reference for better understanding: https://kotlinlang.org/docs/reference/null-safety.html

👍 1

Actually, according your error message you have null not on

title

but on

author

Nizzle94

01/25/2018, 8:35 AM

Yeah I changed all fields based on “title = it.title ?: “Some default value”"

By the way how can I auto increment primary key in room ?

@Entity(tableName = “news”) data class News constructor( @PrimaryKey(autoGenerate = true) var id: Int, var title: String, var author: String, var publishedAt: String ) { }

gildor

01/25/2018, 8:37 AM

https://developer.android.com/reference/android/arch/persistence/room/PrimaryKey.html#autoGenerate()

Yes, like this

autoGenerate should work

Nizzle94

01/25/2018, 8:38 AM

newsDao.insert( News( title = it.title ?: “”, author = it.author ?: “”, publishedAt = it.date ?:“” ) )

If i do like that there error I need to add id

gildor

01/25/2018, 8:38 AM

just make your id nullable

and assign null value there

var id: Int

var id: Int? = null

👍 1

also you should move this property from constructor to body of the class

Nizzle94

01/25/2018, 8:41 AM

@Entity(tableName = “news”) data class News constructor( var title: String, var author: String, var publishedAt: String ) { @PrimaryKey(autoGenerate = true) var id: Int? = null }

like that ?

gildor

01/25/2018, 8:41 AM

yes

Nizzle94

01/25/2018, 8:42 AM

Thank you

👌 1

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