Question

我有一个带有androidx导航（支持栏+导航抽屉）的Java android应用，它正在启动Firebase UI以使用户登录。然后，我决定使用AS转换器将Activity代码迁移到Kotlin以及有关导航设置的一些手动工作。

尽管我付出了很多努力，但仍然无法通过此堆栈

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.gabrielcalero.familytree, PID: 20260
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gabrielcalero.familytree/com.firebase.ui.auth.KickoffActivity}: java.lang.NullPointerException: Attempt to invoke super method 'void androidx.fragment.app.FragmentActivity.onPanelClosed(int, android.view.Menu)' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2793)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864)
    at android.app.ActivityThread.-wrap12(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:156)
    at android.app.ActivityThread.main(ActivityThread.java:6524)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:831)
 Caused by: java.lang.NullPointerException: Attempt to invoke super method 'void androidx.fragment.app.FragmentActivity.onPanelClosed(int, android.view.Menu)' on a null object reference
    at androidx.appcompat.app.AppCompatActivity.onPanelClosed(AppCompatActivity.java:505)
    at androidx.lifecycle.LiveData.observe(LiveData.java:172)
    at com.firebase.ui.auth.KickoffActivity.onCreate(KickoffActivity.java:35)
    at android.app.Activity.performCreate(Activity.java:6910)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2746)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2864) 
    at android.app.ActivityThread.-wrap12(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1567) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:156) 
    at android.app.ActivityThread.main(ActivityThread.java:6524) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:941) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:831)

奇怪的是，在堆栈之后，例外是onPanelClosed，这意味着super为null。这怎么可能？

@Override
public void onPanelClosed(int featureId, Menu menu) {
    super.onPanelClosed(featureId, menu);
}

更新：这是活动代码

package com.gabrielcalero.familytree.ui
import android.content.Intent
import android.os.Bundle
import android.view.MenuItem
import android.widget.ImageView
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.navigation.NavController
import androidx.navigation.findNavController
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.setupWithNavController
import com.firebase.ui.auth.AuthUI
import com.gabrielcalero.familytree.R
import com.gabrielcalero.familytree.ServiceLocator
import com.gabrielcalero.familytree.entity.Constants
import com.gabrielcalero.familytree.ui.picasso.CropCircleTransformation
import com.google.android.material.navigation.NavigationView
import com.google.firebase.auth.FirebaseAuth
import com.squareup.picasso.Picasso
import kotlinx.android.synthetic.main.activity_main.*
import java.util.*

class MainActivity : AppCompatActivity(), NavigationView.OnNavigationItemSelectedListener, FirebaseAuth.AuthStateListener {

private var mUserPicture: ImageView? = null
private var mUserNameTextView: TextView? = null
private var mAuth: FirebaseAuth? = null

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

    mUserPicture = navView.getHeaderView(0).findViewById(R.id.picture)
    mUserNameTextView = navView.getHeaderView(0).findViewById(R.id.display_name)

    mAuth = FirebaseAuth.getInstance().apply { addAuthStateListener { this } }

    launchSignInUI()
}

override fun onStart() {
    super.onStart()
    updateLoggedInUser()
}

private fun updateLoggedInUser() {
    val currentUser = mAuth!!.currentUser
    if (currentUser == null) {
        mUserPicture!!.setImageResource(R.drawable.anonymous)
        mUserNameTextView!!.text = getString(R.string.not_logged_in)
        navView.menu.findItem(R.id.signout).isVisible = false
        navView.menu.findItem(R.id.signin).isVisible = true
        navView.menu.findItem(R.id.personFragment).isEnabled = false
        navView.menu.findItem(R.id.peopleListFragment).isEnabled = false
    } else {
        // show signout
        mUserNameTextView!!.text = currentUser.displayName
        Picasso.with(this)
                .load(currentUser.photoUrl)
                .placeholder(R.drawable.anonymous)
                .error(R.drawable.anonymous)
                .transform(CropCircleTransformation())
                .resize(resources.getDimension(R.dimen.profile_picture_width).toInt(),
                        resources.getDimension(R.dimen.profile_picture_height).toInt())
                .into(mUserPicture)
        navView.menu.findItem(R.id.signout).isVisible = true
        navView.menu.findItem(R.id.signin).isVisible = false
        navView.menu.findItem(R.id.personFragment).isEnabled = true
        navView.menu.findItem(R.id.peopleListFragment).isEnabled = true
    }
}

private fun setupNavigation() {
    setSupportActionBar(toolbar)

    supportActionBar!!.setDisplayShowHomeEnabled(true)
    supportActionBar!!.setDisplayHomeAsUpEnabled(true)

    val navController : NavController = findNavController(R.id.nav_host_fragment)
    val appBarConfiguration = AppBarConfiguration(navController.graph, drawerLayout)
    toolbar.setupWithNavController(navController, appBarConfiguration)
    navView.setupWithNavController(navController)
    navView.setNavigationItemSelectedListener(this)
}

private fun launchSignInUI() {
    // Choose authentication providers
    val providers = Arrays.asList(
            AuthUI.IdpConfig.EmailBuilder().build(),
            AuthUI.IdpConfig.GoogleBuilder().build())

    // Create and launch sign-in intent
    startActivityForResult(
            AuthUI.getInstance()
                    .createSignInIntentBuilder()
                    .setAvailableProviders(providers)
                    .setLogo(R.drawable.logo)
                    .build(),
            Constants.REQUEST_CODE_SIGN_IN)
}


override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    //updateLoggedInUser()
}

override fun onNavigationItemSelected(menuItem: MenuItem): Boolean {
    val navController = findNavController(R.id.nav_host_fragment)
    when (menuItem.itemId) {
        R.id.signout -> signout()
        R.id.signin -> launchSignInUI()
        R.id.personFragment -> {
            navController.popBackStack(R.id.peopleListFragment, false)
            navController.navigate(R.id.personFragment)
            drawerLayout?.closeDrawers()
            return true
        }
        else -> {
            navController.popBackStack(R.id.peopleListFragment, false)
            drawerLayout?.closeDrawers()
            return true
        }
    }
    drawerLayout?.closeDrawers()
    return true
}

private fun signout() {
    val navController = findNavController(R.id.nav_host_fragment)

    AuthUI.getInstance()
            .signOut(this)
            .addOnCompleteListener {
                navView.menu.findItem(R.id.signout).isVisible = false
                navController.popBackStack(R.id.peopleListFragment, false)
            }

}

override fun onAuthStateChanged(firebaseAuth: FirebaseAuth) {
    ServiceLocator.getRepository(application).setCurrentUserId(firebaseAuth.uid)
    updateLoggedInUser()
}

}

Answer 1

问题出在Java到Kotlin的转换中。在这种情况下，我已通过删除未使用的依赖项对其进行了修复

implementation "androidx.core:core-ktx:+"

我想当我完成所有Java类的转换后，我将不得不用-ktx对应项替换所有androidx依赖项

NullPointerException从Kotlin活动启动Firebase Auth UI活动

1 个答案: