应用程序不断停止，logcat 错误无法理解

Question

请原谅我糟糕的问题起草技巧，请帮助我理解 logcat 中显示的错误，我认为这是我的应用停止的原因

我的主活动文件

    package com.syddhoo.bookapp.pack
    
    import androidx.appcompat.app.AppCompatActivity
    import android.os.Bundle
    import android.view.MenuItem
    import android.widget.FrameLayout
    import androidx.appcompat.widget.Toolbar
    import androidx.appcompat.app.ActionBarDrawerToggle
    import androidx.core.view.GravityCompat
    import androidx.drawerlayout.widget.DrawerLayout
    import androidx.coordinatorlayout.widget.CoordinatorLayout
    import com.google.android.material.navigation.NavigationView
    import com.syddhoo.bookapp.*
    
    class MainActivity : AppCompatActivity() {
        lateinit var drawerLayout: DrawerLayout
        lateinit var coordinatorLayout: CoordinatorLayout
        lateinit var toolbar: Toolbar
        lateinit var frameLayout: FrameLayout
        lateinit var navigationView: NavigationView

    var previousMenuItem : MenuItem? = null

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

        drawerLayout = findViewById(R.id.drawerLayout)
        coordinatorLayout = findViewById(R.id.coordinatorLayout)
        toolbar = findViewById(R.id.toolbar)
        frameLayout = findViewById(R.id.frameLayout)
        navigationView = findViewById(R.id.navigationView)
        setUpToolBar()

        openDashboard()

        val actionBarDrawerToggle = ActionBarDrawerToggle(this@MainActivity, drawerLayout,
            R.string.open_drawer,
            R.string.close_drawer
        )
        drawerLayout.addDrawerListener(actionBarDrawerToggle)
        actionBarDrawerToggle.syncState()
        navigationView.setNavigationItemSelectedListener {
            if(previousMenuItem != null){
                previousMenuItem?.isChecked = false
            }
            it.isCheckable = true
            it.isChecked = true
            previousMenuItem = it

            when(it.itemId){
                R.id.dashboard ->{
                    openDashboard()
                    drawerLayout.closeDrawers()
                }
                R.id.favourite ->{
                    supportFragmentManager.beginTransaction().replace(
                        R.id.frameLayout,
                        FavouritesFragment()
                    )
                        .commit()

                    supportActionBar?.title ="Favourites"
                    drawerLayout.closeDrawers()
                }
                R.id.profile ->{
                    supportFragmentManager.beginTransaction().replace(
                        R.id.frameLayout,
                        ProfileFragment()
                    )
                        .commit()

                    supportActionBar?.title ="Profile"
                    drawerLayout.closeDrawers()
                }
                R.id.about ->{
                    supportFragmentManager.beginTransaction().replace(
                        R.id.frameLayout,
                        AboutAppFragment()
                    )
                        .commit()
                    
                    supportActionBar?.title ="About App"
                    drawerLayout.closeDrawers()
                }
            }
            return@setNavigationItemSelectedListener true
        }
    }

    fun setUpToolBar(){
        setSupportActionBar(toolbar)
        supportActionBar?.title = "Toolbar Title"
        supportActionBar?.setHomeButtonEnabled(true)
        supportActionBar?.setDisplayHomeAsUpEnabled(true)

    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        val id = item.itemId
        if(id== R.id.home){
            drawerLayout.openDrawer(GravityCompat.START)

        }
        return super.onOptionsItemSelected(item)
    }
    fun openDashboard(){
        val fragment = DashboardFragment()
        val transaction = supportFragmentManager.beginTransaction()
        transaction.replace(R.id.frameLayout,fragment)
        transaction.commit()
        supportActionBar?.title = "Dashboard"
        navigationView.setCheckedItem(R.id.dashboard)
    }

    override fun onBackPressed() {
        val frag = supportFragmentManager.findFragmentById(R.id.frameLayout)

        when(frag){
            !is DashboardFragment -> openDashboard()
            else -> super.onBackPressed()
        }
    }

}

指向第 34 行的 Logcat 错误 setUpToolBar() 和第 93 行 setSupportActionBar(toolbar) 在主要活动中 我的 Logcat

2021-05-27 20:15:40.373 30082-30082/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.syddhoo.bookapp, PID: 30082
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.syddhoo.bookapp/com.syddhoo.bookapp.pack.MainActivity}: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3792)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3968)
    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$H.handleMessage(ActivityThread.java:2307)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:246)
    at android.app.ActivityThread.main(ActivityThread.java:8506)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1139)
 Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
    at androidx.appcompat.app.AppCompatDelegateImpl.setSupportActionBar(AppCompatDelegateImpl.java:572)
    at androidx.appcompat.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:159)
    at com.syddhoo.bookapp.pack.MainActivity.setUpToolBar(MainActivity.kt:93)
    at com.syddhoo.bookapp.pack.MainActivity.onCreate(MainActivity.kt:34)
    at android.app.Activity.performCreate(Activity.java:8198)
    at android.app.Activity.performCreate(Activity.java:8182)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3765)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3968) 
    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$H.handleMessage(ActivityThread.java:2307) 
    at android.os.Handler.dispatchMessage(Handler.java:106) 
    at android.os.Looper.loop(Looper.java:246) 
    at android.app.ActivityThread.main(ActivityThread.java:8506) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1139) 

错误似乎与操作栏有关。我有什么需要进口的吗？我是一个非常初学者的 android 开发人员，也是堆栈溢出的新手。任何建议都是公开欢迎的。提前致谢。

Answer 1

错误提示

这个 Activity 已经有一个由窗口装饰提供的操作栏。 不要请求 Window.FEATURE_SUPPORT_ACTION_BAR 并设置 在您的主题中将 windowActionBar 设置为 false 以使用工具栏。

您需要更改themes.xml 中的代码。

它应该有这样的线条。

<style name="Theme.projectName" parent="Theme.MaterialComponents.Light.NoActionBar">

NoActionBar 很重要。它将禁用默认的操作栏。