Java Kotlin应用程序打开活动2，按钮崩溃

这就是logcat中的错误，但是当我试图在清单中声明“CreateNoteFragment”时，只有.MainActivity&.SplashScreen出现，不允许我声明.CreateNoteFragment

我的CreateNoteFragment还引用了“BaseFragment”活动，如下所示。 我的按钮点击代码在。MainActivity是唯一不会被破坏的地方，下面是代码。当点击它崩溃的应用程序，任何帮助将不胜感激

    android.content.ActivityNotFoundException: Unable to find explicit activity class {com.moradi.moradinotespro/com.moradi.moradinotespro.CreateNoteFragment}; have you declared this activity in your AndroidManifest.xml?

包括舱单

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.moradi.moradinotespro">

    <!-- Permissions
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
    -->

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity"/>
            <activity android:name=".SplashScreenActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>
        </activity>
    </application>

</manifest>

CreateNoteFragment活动

class CreateNoteFragment : BaseFragment() {
    var currentDate:String? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {

        }
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_create_note, container, false)
    }

    companion object {
        @JvmStatic
        fun newInstance() =
            CreateNoteFragment().apply {
                arguments = Bundle().apply {
                }
            }
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        val sdf = SimpleDateFormat("dd/m/yyyy hh:m:ss")
        currentDate = sdf.format(Date())

        tvDateTime.text = currentDate

        imgDone.setOnClickListener {
            //Save Note
            saveNote()
        }

        imgBack.setOnClickListener {
            replaceFragment(HomeFragment.newInstance(),  false)
        }
    }
    private fun saveNote() {
        if (etNoteTitle.text.isNullOrEmpty()) {
            Toast.makeText(context, "Title Required", Toast.LENGTH_SHORT).show()
        }
        if (etNoteSubTitle.text.isNullOrEmpty()) {
            Toast.makeText(context, "SubTitle Required", Toast.LENGTH_SHORT).show()
        }

        if (etNoteDesc.text.isNullOrEmpty()) {
            Toast.makeText(context, "Note Required", Toast.LENGTH_SHORT).show()
        }



        launch {
        val notes = Notes()
            notes.title = etNoteTitle.text.toString()
            notes.subTitle = etNoteSubTitle.text.toString()
            notes.noteText = etNoteDesc.text.toString()
            notes.dateTime = currentDate
            context?.let {
            NotesDatabase.getDatabase(it).noteDao().insertNotes(notes)
                etNoteTitle.setText("")
                etNoteSubTitle.setText("")
                etNoteDesc.setText("")
            }

        }
    }

    private fun replaceFragment(fragment: Fragment, istransition: Boolean) {
        val fragmentTransition = activity!!.supportFragmentManager.beginTransaction()

        if (istransition) {
            fragmentTransition.setCustomAnimations(
                android.R.anim.slide_out_right,
                android.R.anim.slide_in_left
            )
        }
        fragmentTransition.replace(R.id.frame_layout, fragment)
            .addToBackStack(fragment.javaClass.simpleName)
    }
}

这里的问题是：

fabBtnCreateNote.setOnClickListener {
            val intent = Intent(this, CreateNoteFragment::class.java) 
            startActivity(intent)

        }

CreateNoteFragment不是活动，因此不能将其作为活动启动

首先，您需要创建main_activity.xml文件和带有“frame_layout”的Framelayout的单独id，如下所示：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/frame_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

</FrameLayout>

您需要将HomeFragment替换为CreateNoteFragment：

    fabBtnCreateNote.setOnClickListener {
        val newFragment = CreateNoteFragment.newInstance()
        activity?.let {activity->
            val transaction = activity.supportFragmentManager.beginTransaction()
        // Replace whatever is in the fragment_container view with this fragment,
        // and add the transaction to the back stack if needed
           transaction.replace(R.id.fragment_container, newFragment,CreateNoteFragment::class.simpleName);
        // Commit the transaction
           transaction.commit();  
      }
}

您的CreateNoteFragment已添加到后堆栈中，所以单击后退按钮时只需调用onBackPress（）： 更改您的代码：

imgBack.setOnClickListener {
        activity.onBackPress()
    }

---

检查是否在清单中定义了MainActivity。如果您显示splashscreen代码，如果您要从splashwell转到mainactivity，它很复杂，我想我正试图转到CreateNoteFragment活动，但在清单中，它不允许我将CreateNoteFragment添加到清单中，仅允许Splash和Main，但从Splash转到主片段，然后当我单击add note按钮转到CreateNoteFragment时，它崩溃我用更多的代码更新了这篇文章当我更改代码时，你不能在清单中添加片段，但它表示未解析引用：newFragment newFragment=new CreateNoteFragment（）；和未解决的参考：FragmentTransaction我刚刚用Kotlin版本更新了我的答案，希望它能解决您的问题谢谢，不幸的是，更新后的代码仍在崩溃，这很奇怪，但我认为这与其他原因有关，因为logcat现在显示了java.lang.ClassCastException:com.google.android.material.floatingactionbutton.floatingactionbutton无法转换为android.view.ViewGroup。请显示您的新代码和main_activity.xml代码！

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

    fabBtnCreateNote.setOnClickListener {
        val newFragment = CreateNoteFragment.newInstance()
        activity?.let {activity->
            val transaction = activity.supportFragmentManager.beginTransaction()
        // Replace whatever is in the fragment_container view with this fragment,
        // and add the transaction to the back stack if needed
           transaction.replace(R.id.fragment_container, newFragment,CreateNoteFragment::class.simpleName);
        // Commit the transaction
           transaction.commit();  
      }
}

imgBack.setOnClickListener {
        activity.onBackPress()
    }