retrofit Give kotlin.KotlinNullPointerException - kotlin

Question

Data get from the Sql server and get data json. this json data parsing retofit2.
Created Login Activity but its give error
MainActivity.kt
class MainActivity : AppCompatActivity() {
internal lateinit var api : APIInterface
private var compositeDisposable : CompositeDisposable? = null
var userName : String? = null
var password : String? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
btnLogin.setOnClickListener {
userName = tvUsername.text.toString()
password = tvPassword.text.toString()
getUserName(userName!!,password!!)
}
}
fun getUserName(user : String, pass : String){
val retrofit = APIClient.apIClient
if (retrofit != null) {
api = retrofit.create(APIInterface::class.java)
}
compositeDisposable!!.add(api.getLoginData(user, pass)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe({
if (it.success.equals(1)){
val intent = Intent(this,Company::class.java)
startActivity(intent)
Toast.makeText(this,"Login Successfully!!!",Toast.LENGTH_LONG).show()
}else{
Toast.makeText(this,"UserName or Password is Wrong!!!",Toast.LENGTH_LONG).show()
}
},{
Toast.makeText(this, it.message, Toast.LENGTH_LONG).show()
})
)
}
}
when Debbuger reached on compositeDisposable!!.add(api.getLoginData(user, pass) it's give Error kotlin.kotlinNullPointerException
RestApi Url :
http://localhost/Account/Login.php?user=ABC&pass=1
APIClient.kt
object APIClient {
val BASE_URL = "http://10.0.2.2/Account/"
var retrofit:Retrofit? = null
val apIClient:Retrofit?
get() {
if (retrofit == null)
{
retrofit = Retrofit.Builder().
baseUrl(BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.addCallAdapterFactory(RxJava2CallAdapterFactory.create())
.build()
}
return retrofit
}
}
APIInterface.kt
interface APIInterface {
#GET("Login.php")
fun getLoginData(#Query("user") user : String,
#Query("pass") pass : String) : Observable<LoginList>
}

Answer 1

The most likely cause for the NullPointerException is that compositeDisposable is null.
At the beginning of MyActivity that variable is initialised to null and then it's never changed, so when you use the !! operator the exception is thrown.
I think you can initialise compositeDisposable directly with the correct value, i.e. something like val compositeDisposable = CompositeDisposable().
Also, val should be preferred over var whenever possible – as immutability is easier to control – and userName and password could probably be local variable or at least private