When I add button in "activity_main" The app stop on the AVD but If I delete the button, app run normally.
If I make the button as comment or delete this, The app run correctly. What should I do?
please teach me What I have to do.
This is Logcat.
2022-06-29 21:41:45.282 10486-10486/com.JS.noteapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.JS.noteapp, PID: 10486
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.JS.noteapp/com.JS.noteapp.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.LayoutInflater android.view.Window.getLayoutInflater()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3365)
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.NullPointerException: Attempt to invoke virtual method 'android.view.LayoutInflater android.view.Window.getLayoutInflater()' on a null object reference
at android.app.Activity.getLayoutInflater(Activity.java:5060)
at com.JS.noteapp.MainActivity.<init>(MainActivity.kt:13)
at java.lang.Class.newInstance(Native Method)
at android.app.AppComponentFactory.instantiateActivity(AppComponentFactory.java:95)
at androidx.core.app.CoreComponentFactory.instantiateActivity(CoreComponentFactory.java:45)
at android.app.Instrumentation.newActivity(Instrumentation.java:1253)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3353)
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) And This is my activity_main. I think it hasn't problem.......
<?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"
tools:context=".MainActivity">
<TextView
android:id="@ id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:text="Memo List"
android:textSize="28sp"
android:textStyle="bold"
android:textColor="@color/black"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@ id/edittest_memo"
android:layout_width="280dp"
android:layout_height="wrap_content"
android:hint="App Memo..."
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginStart="22dp"
android:layout_marginBottom="12dp"/>
<Button
android:id="@ id/button_add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="12dp"
android:text="Add"
android:textAllCaps="false"
android:textColor="@color/white"
android:background="@drawable/button_red"
android:layout_marginEnd="10dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@id/edittest_memo" />
<androidx.recyclerview.widget.RecyclerView
android:id="@ id/recyclerView"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="@ id/edittest_memo"
app:layout_constraintTop_toBottomOf="@ id/title"
tools:layout_editor_absoluteX="0dp"
android:layout_margin="20dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>And This is my MainActivity.kt
package com.JS.noteapp
import android.annotation.SuppressLint
import android.os.AsyncTask
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.LinearLayoutManager
import com.JS.noteapp.databinding.ActivityMainBinding
@SuppressLint("StaticFieldLeak")
class MainActivity : AppCompatActivity() {
var binding: ActivityMainBinding = ActivityMainBinding.inflate(layoutInflater) // create ActivityMainBinding Object.
lateinit var db: MemoDatabase // lateinit 나중에 초기화.
var memoList = listOf<MemoEntity>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//setContentView(R.layout.activity_main) // change as comment.
setContentView(binding.root) // get root layout of activity_main.xml
binding.buttonAdd.setOnClickListener {
val memo = MemoEntity(null, binding.edittestMemo.text.toString())
insertMemo(memo)
}
binding.recyclerView.layoutManager = LinearLayoutManager(this)
db = MemoDatabase.getInstance(this)!!
}
//1. Insert Data
//2. Get Data
//3. Delete Data
//4. Set recyclerView
fun insertMemo(memo: MemoEntity) {
// 1, MainThread vs WorkerThread(Background Thread)
// UI관련 작업 - MainThread 에서 이루어짐
// 데이터 통신 - WorkerThread 에서 이루어짐
object : AsyncTask<Unit, Unit, Unit>() {
override fun doInBackground(vararg params: Unit?) {
db.memoDAO().insert(memo)
}
override fun onPostExecute(result: Unit?) { // execute 후에 작업할 내용
super.onPostExecute(result)
getAllMemos()
}
}
}
fun getAllMemos() {
val getTask = object : AsyncTask<Unit, Unit, Unit>() {
override fun doInBackground(vararg params: Unit?) {
memoList = db.memoDAO().getAll()
}
override fun onPostExecute(result: Unit?) {
super.onPostExecute(result)
setRecyclerView(memoList)
}
}
getTask.execute()
}
fun deleteMemo() {
}
fun setRecyclerView(memoList: List<MemoEntity>) {
binding.recyclerView.adapter = MyAdapter(this, memoList)
}
}CodePudding user response：
You are using .inflate() in a null object in the first line of your MainActivity code.
See Binding docs here.
To initialize binding you should do like this:
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater) // initialized here
setContentView(binding.root) // set the view to root binding
// now you can call your binding for anything
}
}
CodePudding user response：
@Thales Isidoro
I change my project like this.
- MainActivity
package com.JS.noteapp
import android.annotation.SuppressLint
import android.os.AsyncTask
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.LinearLayoutManager
import com.JS.noteapp.databinding.ActivityMainBinding
@SuppressLint("StaticFieldLeak")
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding // create ActivityMainBinding Object.
lateinit var db: MemoDatabase // lateinit 나중에 초기화.
var memoList = listOf<MemoEntity>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//setContentView(R.layout.activity_main) // change as comment.
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root) // get root layout of activity_main.xml
binding.buttonAdd.setOnClickListener {
val memo = MemoEntity(null, binding.edittestMemo.text.toString())
insertMemo(memo)
}
binding.recyclerView.layoutManager = LinearLayoutManager(this)
db = MemoDatabase.getInstance(this)!!
}
//1. Insert Data
//2. Get Data
//3. Delete Data
//4. Set recyclerView
fun insertMemo(memo: MemoEntity) {
// 1, MainThread vs WorkerThread(Background Thread)
// UI관련 작업 - MainThread 에서 이루어짐
// 데이터 통신 - WorkerThread 에서 이루어짐
object : AsyncTask<Unit, Unit, Unit>() {
override fun doInBackground(vararg params: Unit?) {
db.memoDAO().insert(memo)
}
override fun onPostExecute(result: Unit?) { // execute 후에 작업할 내용
super.onPostExecute(result)
getAllMemos()
}
}
}
fun getAllMemos() {
val getTask = object : AsyncTask<Unit, Unit, Unit>() {
override fun doInBackground(vararg params: Unit?) {
memoList = db.memoDAO().getAll()
}
override fun onPostExecute(result: Unit?) {
super.onPostExecute(result)
setRecyclerView(memoList)
}
}
getTask.execute()
}
fun deleteMemo() {
}
fun setRecyclerView(memoList: List<MemoEntity>) {
binding.recyclerView.adapter = MyAdapter(this, memoList)
}
}- activity_main
<?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"
tools:context=".MainActivity">
<TextView
android:id="@ id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:text="Memo List"
android:textSize="28sp"
android:textStyle="bold"
android:textColor="@color/black"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="@ id/edittest_memo"
android:layout_width="280dp"
android:layout_height="wrap_content"
android:hint="App Memo..."
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginStart="22dp"
android:layout_marginBottom="12dp"/>
<Button
android:id="@ id/button_add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="12dp"
android:text="Add"
android:textAllCaps="false"
android:textColor="@color/white"
android:background="@drawable/button_red"
android:layout_marginEnd="10dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@id/edittest_memo" />
<androidx.recyclerview.widget.RecyclerView
android:id="@ id/recyclerView"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="@ id/edittest_memo"
app:layout_constraintTop_toBottomOf="@ id/title"
tools:layout_editor_absoluteX="0dp"
android:layout_margin="20dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>but I still have Error Logcat
2022-06-29 22:07:31.140 11738-11738/com.JS.noteapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.JS.noteapp, PID: 11738
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.JS.noteapp/com.JS.noteapp.MainActivity}: android.view.InflateException: Binary XML file line #33 in com.JS.noteapp:layout/activity_main: Binary XML file line #33 in com.JS.noteapp:layout/activity_main: Error inflating class Button
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: android.view.InflateException: Binary XML file line #33 in com.JS.noteapp:layout/activity_main: Binary XML file line #33 in com.JS.noteapp:layout/activity_main: Error inflating class Button
Caused by: android.view.InflateException: Binary XML file line #33 in com.JS.noteapp:layout/activity_main: Error inflating class Button
Caused by: java.lang.IllegalArgumentException: The style on this component requires your app theme to be Theme.AppCompat (or a descendant).
at com.google.android.material.internal.ThemeEnforcement.checkTheme(ThemeEnforcement.java:241)
at com.google.android.material.internal.ThemeEnforcement.checkAppCompatTheme(ThemeEnforcement.java:211)
at com.google.android.material.internal.ThemeEnforcement.checkCompatibleTheme(ThemeEnforcement.java:146)
at com.google.android.material.internal.ThemeEnforcement.obtainStyledAttributes(ThemeEnforcement.java:75)
at com.google.android.material.button.MaterialButton.<init>(MaterialButton.java:228)
at com.google.android.material.button.MaterialButton.<init>(MaterialButton.java:219)
at com.google.android.material.theme.MaterialComponentsViewInflater.createButton(MaterialComponentsViewInflater.java:43)
at androidx.appcompat.app.AppCompatViewInflater.createView(AppCompatViewInflater.java:129)
at androidx.appcompat.app.AppCompatDelegateImpl.createView(AppCompatDelegateImpl.java:1565)
at androidx.appcompat.app.AppCompatDelegateImpl.onCreateView(AppCompatDelegateImpl.java:1616)
at android.view.LayoutInflater.tryCreateView(LayoutInflater.java:1059)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:995)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:959)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1121)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1082)
at android.view.LayoutInflater.inflate(LayoutInflater.java:680)
at android.view.LayoutInflater.inflate(LayoutInflater.java:532)
at com.JS.noteapp.databinding.ActivityMainBinding.inflate(ActivityMainBinding.java:60)
at com.JS.noteapp.databinding.ActivityMainBinding.inflate(ActivityMainBinding.java:54)
at com.JS.noteapp.MainActivity.onCreate(MainActivity.kt:21)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
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)
2022-06-29 22:07:31.141 11738-11738/com.JS.noteapp E/AndroidRuntime: 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)