[英]Why onBackPressed() is not fired when touching Back-Button / Android
為了重現我的問題,我做了一個小項目。 它有兩個活動。
這是MainActivity.kt文件:
package me.soft.trybackbtnaction
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
fun fireSubActivity(view: View) {
val intent = Intent(this, SubActivity::class.java).apply {}
startActivity(intent)
} /* End of fireSubActivity */
}
這是SubActivity.kt文件:
package me.soft.trybackbtnaction
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
class SubActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_sub)
}
override fun onBackPressed() {
super.onBackPressed()
println("onBackPressed CALLED")
}
}
這是AndroidManifest.xml文件:
<application
android:allowBackup="true"
android:dataExtractionRules="@xml/data_extraction_rules"
android:fullBackupContent="@xml/backup_rules"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.TryBackBtnAction"
tools:targetApi="31">
<activity
android:name=".SubActivity"
android:exported="false"
android:parentActivityName=".MainActivity" />
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
下面要完成的是活動 XML 文件。
activity_main.xml :
<?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">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="fireSubActivity"
android:text="Fire Sub-Activity"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
活動_sub.xml :
<?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=".SubActivity">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello Sub-Activity"
android:textSize="34sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
運行應用程序並從子活動中點擊后退箭頭時,我希望調用 onBackPressed() function,但這不會發生。
您可以在適用於片段和活動的較新版本的AppCompatActivity
上嘗試新的onBackPressedDispatcher
。
例子:
onBackPressedDispatcher.addCallback(this, object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
// handle back press here.
}
})
val dispatcher = requireActivity().onBackPressedDispatcher
dispatcher.addCallback(this, object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
// handle back press in fragments.
}
})
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.