Android Kotlin java.lang.ClassCastException

Question

When I run the code, I this Exception

And this is the part that has problem.

for every 60 seconds, it does function broadcastTEK, which is sending string generatedtek to other activity (AppCompatActivity()), which is BLEAdvertiser.

The code where it gets string generatedtek on BLEAdvertiser is below:

So it is supposed to print received string on Logcat, but the app throws exception. Why is it? I have google searched about this exception, and some people say it happens because the variable type that I have sent doesn't match the type when I get the variable. But on my code, they are all String... What could be the problem?

Dharmender Manral · Accepted Answer · 2021-06-22 18:10:34Z

1

Try with the following code it will help you.

class TestActivity : AppCompatActivity(), BTFragment.BLEAdvertiser {

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_test)

    //Make sure your BTFragment calling from this activity
}

override fun receiveData(encryptedtk: String) {
    toast(encryptedtk)
 }

}


class BTFragment : Fragment() {
private lateinit var  bleAdvertiser: BLEAdvertiser
override fun onAttach(context: Context) {
    super.onAttach(context)
    if (context is BLEAdvertiser) this.bleAdvertiser = context
}


fun broadcastTEk(text: String) {
 this.bleAdvertiser.receiveData(text)
}


interface BLEAdvertiser {
    fun receiveData(encryptedtk: String)
}
}

answered Jun 22, 2021 at 18:10

Dharmender Manral

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3 Comments

Hally Over a year ago

Does it mean I have to create one new kotlin class named Test activity?

Eselfar Over a year ago

No, you need your MainActivity to implement BLEAdvertiser. At the moment this is not the case that's why the cast fails (when you do activity as BLEAdvertiser)

Hally Over a year ago

But in this case, isn't the encrytpedtek passed to MainActivity? I want to use the variable on BLEAdvertiser. If I have receiveData on MainActivity, how do I use that passed encrytpedtek in BLEAdvertiser?

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