Kotlin 多平台应用程序在启动时崩溃

Question

When I run my app, it is supposed to show a screen for a user to create an account or sign in. I had the code working as a regular kotlin app and decided to make a multiplatform app instead so I remade the project as multiplatform. KMM does not support this code:

import kotlinx.android.synthetic.main.activity_sign_in.*

so I had to change to ViewBinding. Here is the code I used previously and what I changed it to:

Before:

import android.content.Intent
import android.os.Bundle
import android.widget.EditText
import com.cj.globekotlin.Extensions.toast
import com.cj.globekotlin.FirebaseUtils.firebaseAuth
import kotlinx.android.synthetic.main.activity_sign_in.*

class SignInActivity : AppCompatActivity() {
    lateinit var signInEmail: String
    lateinit var signInPassword: String
    lateinit var signInInputsArray: Array<EditText>

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

        signInInputsArray = arrayOf(etSignInEmail, etSignInPassword)
        btnCreateAccount2.setOnClickListener {
            startActivity(Intent(this, CreateAccountActivity::class.java))
            finish()
        }

        btnSignIn.setOnClickListener {
            signInUser()
        }
    }

    private fun notEmpty(): Boolean = signInEmail.isNotEmpty() && signInPassword.isNotEmpty()

    private fun signInUser() {
        signInEmail = etSignInEmail.text.toString().trim()
        signInPassword = etSignInPassword.text.toString().trim()

        if (notEmpty()) {
            firebaseAuth.signInWithEmailAndPassword(signInEmail, signInPassword)
                .addOnCompleteListener { signIn ->
                    if (signIn.isSuccessful) {
                        startActivity(Intent(this, HomeActivity::class.java))
                        toast("signed in successfully")
                        finish()
                    } else {
                        toast("sign in failed")
                    }
                }
        } else {
            signInInputsArray.forEach { input ->
                if (input.text.toString().trim().isEmpty()) {
                    input.error = "${input.hint} is required"
                }
            }
        }
    }
}

Current:

import android.content.Intent
import android.os.Bundle
import android.widget.EditText
import com.cj.globemultiplatform.android.Extensions.toast
import com.cj.globemultiplatform.android.FirebaseUtils.firebaseAuth
import com.cj.globemultiplatform.android.databinding.ActivitySignInBinding

class SignInActivity : AppCompatActivity() {
    lateinit var signInEmail: String
    lateinit var signInPassword: String
    lateinit var signInInputsArray: Array<EditText>

    private lateinit var binding: ActivitySignInBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivitySignInBinding.inflate(layoutInflater)
        setContentView(R.layout.activity_sign_in)

        signInInputsArray = arrayOf(binding.etSignInEmail, binding.etSignInPassword)
        binding.btnCreateAccount2.setOnClickListener {
            startActivity(Intent(this, CreateAccountActivity::class.java))
            finish()
        }

        binding.btnSignIn.setOnClickListener {
            signInUser()
        }
    }

    private fun notEmpty(): Boolean = signInEmail.isNotEmpty() && signInPassword.isNotEmpty()

    private fun signInUser() {
        signInEmail = binding.etSignInEmail.text.toString().trim()
        signInPassword = binding.etSignInPassword.text.toString().trim()

        if (notEmpty()) {
            firebaseAuth.signInWithEmailAndPassword(signInEmail, signInPassword)
                .addOnCompleteListener { signIn ->
                    if (signIn.isSuccessful) {
                        startActivity(Intent(this, HomeActivity::class.java))
                        toast("signed in successfully")
                        finish()
                    } else {
                        toast("sign in failed")
                    }
                }
        } else {
            signInInputsArray.forEach { input ->
                if (input.text.toString().trim().isEmpty()) {
                    input.error = "${input.hint} is required"
                }
            }
        }
    }
}

Initially, I thought that this would work but now whenever I open the app, it crashes. I think this change is what's causing the crashes. Is that possible? If so, how can I fix this?

Answer 1

There are a couple of problems with your android code:

1. There is no connection between your inflated binding and the content you are setting, you should use

binding = ActivitySignInBinding.inflate(layoutInflater)
setContentView(binding.root) 

2. Your lateinit var iables for the inputs are used in the signInUser() method, but it's not initialised. I'd suggest removing that and using binding.signInEmail and the other views.

Also, if you're trying to share code between Android & iOS, you should be aware that you'll need to abstract away any platform specific implementation. For ex: all packages that are android specific will not work on iOS at this moment. This specific code is pretty Android platform heavy, thus I wouldn't even try to share this in a KMM app, only business logic, perhaps up to a ViewModel layer.