android.widget.Toolbar 无法转换为 androidx.appcompat.widget.Toolbar（android 工具栏）
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【中文标题】android.widget.Toolbar 无法转换为 androidx.appcompat.widget.Toolbar（android 工具栏）【英文标题】：android.widget.Toolbar cannot be cast to androidx.appcompat.widget.Toolbar (android toolbar) 【发布时间】：2022-01-11 15:55:24 【问题描述】：MainActivity.kt
package com.sitamadex11.gcectapp
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.MenuItem
import android.view.View
import android.widget.Toast
import androidx.appcompat.widget.Toolbar
import androidx.appcompat.app.ActionBarDrawerToggle
import androidx.drawerlayout.widget.DrawerLayout
import com.google.android.material.navigation.NavigationView
class MainActivity : AppCompatActivity()
lateinit var toggle: ActionBarDrawerToggle
override fun onCreate(savedInstanceState: Bundle?)
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val toolbar: Toolbar = findViewById(R.id.toolbar)
setSupportActionBar(toolbar)
val drawerLayout=findViewById<View>(R.id.drawerLayout) as DrawerLayout
toggle = ActionBarDrawerToggle(this,drawerLayout ,toolbar,R.string.open,R.string.close)
drawerLayout.addDrawerListener(toggle)
toggle.syncState()
supportActionBar?.setDisplayHomeAsUpEnabled(true)
val navView=findViewById<View>(R.id.navView) as NavigationView
navView.setNavigationItemSelectedListener
when(it.itemId)
R.id.nav_home -> Toast.makeText(applicationContext,
"Clicked Home",Toast.LENGTH_SHORT).show()
R.id.nav_aboutus -> Toast.makeText(applicationContext,
"Clicked About Us",Toast.LENGTH_SHORT).show()
R.id.nav_acad -> Toast.makeText(applicationContext,
"Clicked Academics",Toast.LENGTH_SHORT).show()
true
override fun onOptionsItemSelected(item: MenuItem): Boolean
if(toggle.onOptionsItemSelected(item))
return true
return super.onOptionsItemSelected(item)
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout 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:id="@+id/drawerLayout"
android:layout_
android:layout_
tools:context=".MainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_
android:layout_>
<Toolbar
android:layout_
android:layout_
android:id="@+id/toolbar"
android:title="GCECT"
android:background="@color/teal_200"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
/>
<TextView
android:layout_
android:layout_
android:text="ACTIVITY"
android:textSize="40sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
<com.google.android.material.navigation.NavigationView
android:id="@+id/navView"
android:layout_
android:layout_
app:headerLayout="@layout/nav_header"
app:menu="@menu/nav_drawer_menu"
android:layout_gravity="start"
android:fitsSystemWindows="true"/>
</androidx.drawerlayout.widget.DrawerLayout>
logcat 错误信息：
2021-12-06 17:41:58.372 3377-3377/com.sitamadex11.gcectapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.sitamadex11.gcectapp, PID: 3377
java.lang.RuntimeException:**Unable to start activity ComponentInfocom.sitamadex11.gcectapp/com.sitamadex11.gcectapp.MainActivity: java.lang.ClassCastException: android.widget.Toolbar cannot be cast to androidx.appcompat.widget.Toolbar**
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.ClassCastException: android.widget.Toolbar cannot be cast to androidx.appcompat.widget.Toolbar
at com.sitamadex11.gcectapp.MainActivity.onCreate(MainActivity.kt:23)
at android.app.Activity.performCreate(Activity.java:7994)
at android.app.Activity.performCreate(Activity.java:7978)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
如何解决这个问题？
【问题讨论】：
这能回答你的问题吗？ android.widget.Toolbar cannot be cast to androidx.appcompat.widget.Toolbar even though that is not the case 【参考方案1】：发生此错误是因为您的 XML 使用的是基础 android Toolbar，但您的代码正在导入 AndroidX Toolbar
您可以按如下方式更改您的 xml：
<androidx.appcompat.widget.Toolbar
代替：
<Toolbar
【讨论】：
感谢您指出这一点。问题解决了以上是关于android.widget.Toolbar 无法转换为 androidx.appcompat.widget.Toolbar（android 工具栏）的主要内容，如果未能解决你的问题，请参考以下文章
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