为什么我的Android应用程序在目前一切正常的情况下运行两个实例？

我有一个包含三个活动的应用程序

从SharedReferences加载数据的splashscreenActivity（启动器活动）。然后在第二次之后继续MainActivity并退出（finish（））本身

负责UI并对变量和AlarmManager进行必要更改的主要活动

仅由AlarmManager使用的广播接收器。BroadCastReceiver根据Splash的静态值发送通知

一切都很顺利，直到我将材料设计添加到依赖项中，并更新了我的所有布局和所有这些东西。我不确定这是否是导致这个错误的原因。但现在，我的应用程序启动了两个启动屏幕实例。 它并不那么明显，因为它消失了。但在我完成MainActivity并按下back按钮后，MainActivity将返回到另一个MainActivity。 怎么会这样

代码如下：

SplashScreen.java>

package com.example.breathe;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.app.AppCompatDelegate;

import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;

public class SplashScreen extends AppCompatActivity {

    public static boolean breatheToggled = false, persistence = true;
    public static int interval = 0;
    public static boolean TESTING = false;
    public static String BreathePreferencesKey="THE_KEY_TO_THE_VALLEY_OF_ETERNAL_PREFERENCES",
            breatheToggleString = "Isthetoggleswitchonoroff",
            breatheIntervalString = "IntervalForBreatheReminder",
            breathePersistenceString = "StringForPersistenceSwitchKey";
    public static void log(String x){ Log.d("jitin", x); }
    public static void trace(String x){ Log.d("trace", x); }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        trace("Splash Destroyed");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);
//        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);

        //LOAD DATA FROM PREFERENCES
        SharedPreferences preferences = getSharedPreferences(BreathePreferencesKey, 0);
        breatheToggled = preferences.getBoolean(breatheToggleString, breatheToggled);
        interval = preferences.getInt(breatheIntervalString, interval);
        persistence = preferences.getBoolean(breathePersistenceString, persistence);
        log("Read Preferences :"+
                "\nMainSwitch : "+String.valueOf(breatheToggled) +
                "\nInterval   : "+String.valueOf(interval) +
                "\nPersistance: "+String.valueOf(persistence) +
                "\nAutoCancel : "+String.valueOf(!persistence)
        );

        trace("Splash created, going to Main in 1 sec");
        //GO TO MAIN ACTIVITY AFTER DELAY
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                goToMain();
            }
        }, 1000);
    }

    //    public void goToMain(View view){ goToMain();}
    private void goToMain() {
        startActivity((new Intent(SplashScreen.this, MainActivity.class))
                //ALL LOADED DATA TO BE PASSED TO MAIN CLASS AS INTENT
                .putExtra(breatheToggleString, breatheToggled)
                .putExtra(breatheIntervalString, interval)
                .putExtra(breathePersistenceString, persistence)
        );
        finish();
    }
}

MainActivity.java>

package com.example.breathe;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.app.AppCompatDelegate;

import android.annotation.SuppressLint;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.SharedPreferences;
import android.media.AudioManager;
import android.os.Build;
import android.os.Bundle;
import android.os.VibrationEffect;
import android.os.Vibrator;
import android.view.View;
import android.widget.CompoundButton;
import android.widget.SeekBar;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.ToggleButton;

import static com.example.breathe.SplashScreen.TESTING;
import static com.example.breathe.SplashScreen.log;
import static com.example.breathe.SplashScreen.trace;

public class MainActivity extends AppCompatActivity {

    public static boolean toggleState, persistence;
    private int interval;
    private SeekBar intervalBar;
    private ToggleButton toggleButton;
    private TextView intervalText;
    private Switch persistenceSwitch;
    //Intent to BroadCast liSTENER
    PendingIntent calltoBroadcastListener;
    //ALARM MANAGER
    AlarmManager AM;

    @Override
    protected void onDestroy() {
        super.onDestroy();
        trace("Main destroyed");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
        toggleButton = findViewById(R.id.toggleButton);
        intervalText = findViewById(R.id.intervalValue);
        intervalBar = findViewById(R.id.intervalBar);
        persistenceSwitch = findViewById(R.id.persistenceSwitch);

        trace("Main created");
        //OBTAINING DATA FROM INTENT, WHICH COMES FROM SHAREDPREFERENCES LOADED IN THE SPLASH ACTIVITY
        Intent intentData = getIntent();
        toggleState = intentData.getBooleanExtra(SplashScreen.breatheToggleString, SplashScreen.breatheToggled);
        toggleBreatheSwitch(toggleState);
        interval = intentData.getIntExtra(SplashScreen.breatheIntervalString, SplashScreen.interval);
        setInterval();
        intervalBar.setOnSeekBarChangeListener(seekBarChangeListener);
        persistence = intentData.getBooleanExtra(SplashScreen.breathePersistenceString, SplashScreen.persistence);
        persistenceSwitch.setChecked(!persistence);
        persistenceSwitch.setOnCheckedChangeListener(switchChangeListener);

        calltoBroadcastListener = PendingIntent.getBroadcast(
                this,
                1,
                new Intent(this, BreathBroadcastReceiver.class),
                PendingIntent.FLAG_UPDATE_CURRENT
        );
        AM = (AlarmManager) getSystemService(ALARM_SERVICE);
    }

    Switch.OnCheckedChangeListener switchChangeListener = new Switch.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
            if (compoundButton.getId() == R.id.persistenceSwitch) {
                persistence = !b;

                //set state to Shared Preferences
                SharedPreferences.Editor preferences = getSharedPreferences(SplashScreen.BreathePreferencesKey, 0).edit();
                preferences.putBoolean(SplashScreen.breathePersistenceString, persistence);
                preferences.apply();

                log("Saved preference persistence : " + persistence + ", AutoCancel : " + !persistence);
            }
        }
    };

    SeekBar.OnSeekBarChangeListener seekBarChangeListener = new SeekBar.OnSeekBarChangeListener() {
        @SuppressLint("SetTextI18n")
        @Override
        public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
            switch (seekBar.getId()){
                case R.id.intervalBar:
                    setInterval(i);
                    vibrate(30);
                default:
            }
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {}

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            toggleBreatheSwitch(false);
            log("Saved Prefereces : interval : "+interval);
            SharedPreferences.Editor preferences = getSharedPreferences(SplashScreen.BreathePreferencesKey, 0).edit();
            preferences.putInt(SplashScreen.breatheIntervalString, (seekBar.getProgress()+1)*15);
            preferences.apply();
        }
    };

    @SuppressLint("ShortAlarm")
    private void setAlarm(){
        if (AM != null) {
            if (!TESTING)AM.setInexactRepeating(
                    AlarmManager.ELAPSED_REALTIME_WAKEUP,
                    0,
                    1000*60*interval,
                    calltoBroadcastListener
            );
            else AM.setRepeating(
                    AlarmManager.ELAPSED_REALTIME_WAKEUP, 0, 1000*60*1, calltoBroadcastListener);
            log("Alarm Set");
        } else log("Alarm is NULL");
    }

    private void toggleBreatheSwitch(boolean thetoggleState){
        toggleState = thetoggleState;

        //set toggle state to shared preferences;
        toggleButton.setChecked(toggleState);
        SharedPreferences.Editor preferences = getSharedPreferences(SplashScreen.BreathePreferencesKey, 0).edit();
        preferences.putBoolean(SplashScreen.breatheToggleString, toggleState);
        preferences.apply();
        log("Saved preferences : MainSwitch : "+ toggleState);

        //set changes to UI
        if (toggleState){ //REMINDER ON
            toggleButton.setTextColor(getResources().getColor(R.color.colorAccent));
            setAlarm();
        } else { //REMINDER OFF
            toggleButton.setTextColor(getResources().getColor(R.color.colorWhite));
            if (AM != null) AM.cancel(calltoBroadcastListener);
            log("Alarms Revoked");
        }
        vibrate(50);
    }

    public void toggleBreatheSwitch(View view) {
        //dummy function to handle calls from UI
        toggleBreatheSwitch(((ToggleButton)view).isChecked());
    }
    private void vibrate(int mSecs){
        try{ //To avoid vibrating when device is in total silence
            if (((AudioManager)getSystemService(AUDIO_SERVICE)).getRingerMode() == AudioManager.RINGER_MODE_SILENT) return;
        } catch (Exception ignore){}

        Vibrator vibe = (Vibrator) getSystemService(VIBRATOR_SERVICE);
        if ((vibe != null) && (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O))
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q)
                vibe.vibrate(VibrationEffect.createOneShot(mSecs, VibrationEffect.EFFECT_TICK));
            else
                vibe.vibrate(mSecs);
    }

    private void setInterval(){
        //Function to update UI - set intervalText and intervalBar values
        setInterval(interval/15 - 1);
        intervalBar.setProgress(interval/15 - 1);
    }
    @SuppressLint("SetTextI18n")
    private void setInterval(int seekbarValue){
        //Function to update UI - set the intervalText
        int hours, minutes;
        interval = (seekbarValue+1)*15;
        hours = interval/60;
        minutes = interval%60;
        if (hours != 0 ) intervalText.setText(hours + "Hr ");
        if (minutes != 0)
            if (hours != 0)
                intervalText.setText(intervalText.getText().toString() + minutes +"min");
            else intervalText.setText(minutes +"min");
    }
}

BreathBroadcastReceiver.java>

package com.example.breathe;

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.media.AudioAttributes;
import android.net.Uri;
import android.os.Build;

import androidx.core.app.NotificationCompat;

import static com.example.breathe.SplashScreen.log;
import static com.example.breathe.SplashScreen.trace;

public class BreathBroadcastReceiver extends BroadcastReceiver {


    @Override
    public void onReceive(Context context, Intent intent) {
        trace("Broadcast Receiver received, sending notification");
        sendBreatheNotification(context);
    }

    public void sendBreatheNotification(Context context) {
        String NotificationChannelID = "Channel001";
        NotificationManager notifier = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && notifier != null) {
            NotificationChannel chan = new NotificationChannel (
                    NotificationChannelID,
                    "Primary Breathe Reminders",
                    NotificationManager.IMPORTANCE_DEFAULT);
            chan.setSound(
                    Uri.parse("android.resource://" + context.getPackageName() + "/" + R.raw.m),
                    new AudioAttributes.Builder()
                            .setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
                            .setUsage(AudioAttributes.USAGE_ALARM)
                            .build()
            );
            notifier.createNotificationChannel(chan);
        }

        if (notifier != null){
            NotificationCompat.Builder nBuilder = new NotificationCompat.Builder(context, NotificationChannelID)
                    .setAutoCancel(true)
                    .setSmallIcon(R.drawable.ic_lungs)
                    .setContentTitle("Breathe")
                    .setContentText("Don't Forget to Breath Deep.")
                    .setContentInfo("SOME INFO");

//                .setSubText("some sub text as well")
            if (!MainActivity.persistence) nBuilder.setTimeoutAfter(1000*10);

            notifier.notify(1, nBuilder.build());
            log("Breath Notification sent");
        } else log("Notifier null, Notification not displayed");
    }
}

manifest>

MainActivitylayout>

<?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"
    android:padding="18dp"
    tools:context=".MainActivity">

    <androidx.appcompat.widget.AppCompatToggleButton
        android:id="@+id/toggleButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:checked="true"
        android:onClick="toggleBreatheSwitch"
        android:padding="24dp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <androidx.appcompat.widget.AppCompatSeekBar
        android:id="@+id/intervalBar"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="32dp"
        android:max="15"
        android:progress="9"
        app:layout_constraintBottom_toTopOf="@+id/toggleButton"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/intervalText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:text="@string/reminder_interval"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        app:layout_constraintBottom_toTopOf="@+id/intervalBar"
        app:layout_constraintStart_toStartOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/intervalValue"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="32dp"
        app:layout_constraintBaseline_toBaselineOf="@+id/intervalText"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/intervalText" />

    <Switch
        android:id="@+id/persistenceSwitch"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="32dp"
        android:checked="true"
        android:text="@string/persistence_text"
        android:textOff="disabled"
        android:textOn="enabled"
        app:layout_constraintBottom_toTopOf="@+id/intervalText"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/voiceText"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:text="Notification Voice"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        app:layout_constraintBottom_toTopOf="@+id/radioGroup"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <RadioGroup
        android:id="@+id/radioGroup"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="32dp"
        android:orientation="vertical"
        android:gravity="fill"
        app:layout_constraintBottom_toTopOf="@+id/persistenceSwitch"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <com.google.android.material.radiobutton.MaterialRadioButton
            android:id="@+id/radioButton"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Male" />

        <com.google.android.material.radiobutton.MaterialRadioButton
            android:id="@+id/radioButton2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Female" />
    </RadioGroup>

</androidx.constraintlayout.widget.ConstraintLayout>

---

您可能会看到这个讨厌的、长期存在的Android bug：

要进行检查，请在设备上安装应用程序，然后关闭应用程序（设置->应用程序->应用程序->强制退出），然后点击主屏幕上的图标启动应用程序，查看其现在是否正常运行

<?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"
    android:padding="18dp"
    tools:context=".MainActivity">

    <androidx.appcompat.widget.AppCompatToggleButton
        android:id="@+id/toggleButton"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:checked="true"
        android:onClick="toggleBreatheSwitch"
        android:padding="24dp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <androidx.appcompat.widget.AppCompatSeekBar
        android:id="@+id/intervalBar"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="32dp"
        android:max="15"
        android:progress="9"
        app:layout_constraintBottom_toTopOf="@+id/toggleButton"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/intervalText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:text="@string/reminder_interval"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        app:layout_constraintBottom_toTopOf="@+id/intervalBar"
        app:layout_constraintStart_toStartOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/intervalValue"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="32dp"
        app:layout_constraintBaseline_toBaselineOf="@+id/intervalText"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/intervalText" />

    <Switch
        android:id="@+id/persistenceSwitch"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="32dp"
        android:checked="true"
        android:text="@string/persistence_text"
        android:textOff="disabled"
        android:textOn="enabled"
        app:layout_constraintBottom_toTopOf="@+id/intervalText"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <com.google.android.material.textview.MaterialTextView
        android:id="@+id/voiceText"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:text="Notification Voice"
        android:textAppearance="@style/TextAppearance.AppCompat.Medium"
        app:layout_constraintBottom_toTopOf="@+id/radioGroup"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <RadioGroup
        android:id="@+id/radioGroup"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="32dp"
        android:orientation="vertical"
        android:gravity="fill"
        app:layout_constraintBottom_toTopOf="@+id/persistenceSwitch"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <com.google.android.material.radiobutton.MaterialRadioButton
            android:id="@+id/radioButton"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Male" />

        <com.google.android.material.radiobutton.MaterialRadioButton
            android:id="@+id/radioButton2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Female" />
    </RadioGroup>

</androidx.constraintlayout.widget.ConstraintLayout>