package ドメイン.intentflagsampleimport android.content.Intentimport androidx.appcompat.app.AppCompatActivityimport android.os.Bundleimport android.util.Logimport android.widget.Toastimport kotlinx.android.synthetic.main.activity_main.*class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) val data = intent.getStringExtra("sub2_data") if (data != null) { Toast.makeText(applicationContext, data, Toast.LENGTH_SHORT).show() } button.setOnClickListener { startActivity(Intent(this, Sub1Activity::class.java)) } }}package ドメイン.intentflagsampleimport android.content.Intentimport androidx.appcompat.app.AppCompatActivityimport android.os.Bundleimport kotlinx.android.synthetic.main.activity_sub1.*class Sub1Activity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_sub1) button2.setOnClickListener { startActivity(Intent(this, Sub2Activity::class.java)) } }}package ドメイン.intentflagsampleimport android.content.Intentimport androidx.appcompat.app.AppCompatActivityimport android.os.Bundleimport kotlinx.android.synthetic.main.activity_sub2.*class Sub2Activity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_sub2) button3.setOnClickListener { val intent = Intent(this, MainActivity::class.java).apply { flags = Intent.FLAG_ACTIVITY_CLEAR_TOP putExtra("sub2_data", editText.text.toString()) } startActivity(intent) } }}<?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/textView3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="MainActivity" android:textAppearance="@style/TextAppearance.AppCompat.Medium" app:layout_constraintBottom_toTopOf="@+id/button" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/textView3" /></androidx.constraintlayout.widget.ConstraintLayout><?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=".Sub1Activity"> <TextView android:id="@+id/textView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Sub1Activity" android:textAppearance="@style/TextAppearance.AppCompat.Medium" 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" /> <Button android:id="@+id/button2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/textView" /></androidx.constraintlayout.widget.ConstraintLayout><?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=".Sub2Activity"> <TextView android:id="@+id/textView2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Sub2Activity" android:textAppearance="@style/TextAppearance.AppCompat.Medium" app:layout_constraintBottom_toTopOf="@+id/editText" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <Button android:id="@+id/button3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/editText" /> <EditText android:id="@+id/editText" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginEnd="8dp" android:ems="10" android:inputType="textPersonName" android:text="Name" app:layout_constraintBottom_toTopOf="@+id/button3" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.5" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/textView2" /></androidx.constraintlayout.widget.ConstraintLayout>