Question

此处是新的应用程序开发人员。我几天前开始开发应用程序。在我替换了默认的滚动视图之前，它工作得很好。我正在尝试使用类似于reddit的设计制作滚动视图，无尽的盒子具有固定的大小。更改代码后，我希望在滚动视图中有多个大小相同的框。相反，它会在启动时立即崩溃。

我尝试更改了滚动视图的尺寸，并尝试添加子元素，但它仍然对我不起作用

我在日志中收到以下错误消息：

 **2019-11-23 20:41:40.155 10846-10846/com.john.chanapi E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.john.chanapi, PID: 10846
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.john.chanapi/com.john.chanapi.MainActivity}: java.lang.IllegalStateException: Activity com.john.chanapi.MainActivity@1850938 does not have a NavController set on 2131230867
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3047)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3182)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1916)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6898)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.IllegalStateException: Activity com.john.chanapi.MainActivity@1850938 does not have a NavController set on 2131230867
at androidx.navigation.Navigation.findNavController(Navigation.java:61)
at androidx.navigation.ActivityKt.findNavController(Activity.kt:30)
at com.john.chanapi.MainActivity.onCreate(MainActivity.kt:33)
at android.app.Activity.performCreate(Activity.java:7149)
at android.app.Activity.performCreate(Activity.java:7140)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1288)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3027)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3182) 
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1916) 
at android.os.Handler.dispatchMessage(Handler.java:106) 
at android.os.Looper.loop(Looper.java:193) 
at android.app.ActivityThread.main(ActivityThread.java:6898) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:537) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

我的content_main.xml文件：

<?xml version="1.0" encoding="utf-8"?>
    <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/app_bar_main">
    <ScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <LinearLayout
    android:id="@+id/scrollview1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:divider="#312F2F"
    android:orientation="vertical" >
    <TextView
    android:id="@+id/textView2"
    android:layout_width="match_parent"
    android:layout_height="124dp"
    android:text="TextView" />
    <Button
    android:id="@+id/button"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Button" />
    </LinearLayout>
    </ScrollView>
    </androidx.constraintlayout.widget.ConstraintLayout>**

Mainactivity.kt文件：

    package com.john.chanapi

    import android.os.Bundle
    import com.google.android.material.floatingactionbutton.FloatingActionButton
    import com.google.android.material.snackbar.Snackbar
    import androidx.navigation.findNavController
    import androidx.navigation.ui.AppBarConfiguration
    import androidx.navigation.ui.navigateUp
    import androidx.navigation.ui.setupActionBarWithNavController
    import androidx.navigation.ui.setupWithNavController
    import androidx.drawerlayout.widget.DrawerLayout
    import com.google.android.material.navigation.NavigationView
    import androidx.appcompat.app.AppCompatActivity
    import androidx.appcompat.widget.Toolbar
    import android.view.Menu
    class MainActivity : AppCompatActivity() {

    private lateinit var appBarConfiguration: AppBarConfiguration

    override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    val toolbar: Toolbar = findViewById(R.id.toolbar)
    setSupportActionBar(toolbar)

    val fab: FloatingActionButton = findViewById(R.id.fab)
    fab.setOnClickListener { view ->
    Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
    .setAction("Action", null).show()
    }
    val drawerLayout: DrawerLayout = findViewById(R.id.drawer_layout)
    val navView: NavigationView = findViewById(R.id.nav_view)
    val navController = findNavController(R.id.scrollview1)
    // Passing each menu ID as a set of Ids because each
    // menu should be considered as top level destinations.
    appBarConfiguration = AppBarConfiguration(
    setOf(
    R.id.nav_home, R.id.nav_new, R.id.nav_rising,
    R.id.nav_top, R.id.nav_inbox, R.id.nav_message
    ), drawerLayout
    )
    setupActionBarWithNavController(navController, appBarConfiguration)
    navView.setupWithNavController(navController)
    }

    override fun onCreateOptionsMenu(menu: Menu): Boolean {
    // Inflate the menu; this adds items to the action bar if it is present.
    menuInflater.inflate(R.menu.main, menu)
    return true
    }

    override fun onSupportNavigateUp(): Boolean {
    val navController = findNavController(R.id.scrollview1)
    return navController.navigateUp(appBarConfiguration) || super.onSupportNavigateUp()
    }
    }

任何帮助或建议都会帮助我。我已经坚持了几个小时。谢谢！

Answer 1

基于日志，它在findNavController的以下行MainActivity中崩溃：
val navController = findNavController(R.id.scrollview1)。

该活动只是夸大onCreate中的视图，当您尝试获取NavController时，它将失败。

一种简单的验证方法是在comment中此行之后的delete / onCreate代码中检查应用是否崩溃。

如果这是问题所在，则可以将这些代码移至onViewCreated中，其中所有视图均会膨胀。

您可以尝试以下方法：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    val toolbar: Toolbar = findViewById(R.id.toolbar)
    setSupportActionBar(toolbar)
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    val fab: FloatingActionButton = findViewById(R.id.fab)
    fab.setOnClickListener { view ->
    Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
        .setAction("Action", null).show()
    }
    val drawerLayout: DrawerLayout = findViewById(R.id.drawer_layout)
    val navView: NavigationView = findViewById(R.id.nav_view)
    val navController = findNavController(R.id.scrollview1)
    // Passing each menu ID as a set of Ids because each
    // menu should be considered as top level destinations.
    appBarConfiguration = AppBarConfiguration(
        setOf(
            R.id.nav_home, R.id.nav_new, R.id.nav_rising,
            R.id.nav_top, R.id.nav_inbox, R.id.nav_message
        ), drawerLayout
    )
    setupActionBarWithNavController(navController, appBarConfiguration)
    navView.setupWithNavController(navController)
}

如何修复scrollview崩溃的Android应用程序？

1 个答案: