Every intent starts a new task in Android App - how to prevent?

Question

In my application I have several "intents" that I use to transition between different activities in my application. I have noticed a strange behavior that occurs on Samsung devices - but not on Nexus devices - whenever a new intent is created the application launches a second "task" for this new activity! When the user goes to the multi-tasking menu they can see multiple copies of the application! This is not the desired behavior. Any and all advice would be greatly appreciated!

Manifest:

 <application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"
    android:launchMode="singleInstance">
    <activity
        android:name=".MainActivity"
        android:screenOrientation="portrait"
        android:launchMode="singleInstance">
    </activity>
    <activity
        android:name=".Settings_area"
        android:screenOrientation="portrait" />
    <meta-data
        android:name="com.google.android.geo.API_KEY"
        android:value="AIzaSyDieXTCaFoIL0kJ_IM4UMBSQL3sNn92AWM" />

    <activity
        android:name=".MapsActivity"
        android:label="@string/title_activity_maps" />
    <activity android:name=".Splash"
        android:launchMode="singleInstance">


        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>

    </activity>
    <activity android:name=".aboutPageActivity" />
    <activity android:name=".turnOffFromNotification"
        android:noHistory="true"></activity>
</application>

I have already attempted removing the launch modes as well as changing the application launch mode to singleTop and standard.

Intent that creates a second instance:

 if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {

                new Handler().postDelayed(new Runnable(){
                    @Override
                    public void run() {
            /* Create an Intent that will start the Menu-Activity. */
                        Intent mainIntent = new Intent(Splash.this,MainActivity.class);
                        Splash.this.startActivity(mainIntent);
                        Splash.this.finish();
                    }
                }, splashDisplayLength);
                return;
            }

Intent that creates a third instance:

    public void goToAboutPage()
{
    Intent goToAboutPage = new Intent(this, aboutPageActivity.class); //create the intent to go to the map screen
    startActivity(goToAboutPage); //actually go to the map screen
}

A third instance can also be created from launching a settings intent:

    public void changeToSettingsScreen() //changes the screen to the setting screen
{
    readyToSendPackets = false;
    sendSwitch.setChecked(false);
    //  textView.setText("NOT sending"); //set the textview to advise users packets are not being sent
    Intent goToSettings = new Intent(this, Settings_area.class);
    startActivity(goToSettings);
}

I also over rode the onNewIntent Method:

    protected void onNewIntent(Intent intent) {
  //  super.onNewIntent(intent); //REMOVED THIS TO AVOID DOUBLE INSTANTIATION ON TOUCHWIZ IF ANYTHING BREAKS LOOK HERE FIRST
    setIntent(intent); //this allows us to recieve the  extras bundled with the intent
    // System.out.println("Here is the bindle: " +  getIntent().getExtras());
    if (getIntent().getExtras() != null) //check to see if there are any extras, there wont be on apps first start
    {
        Bundle extras = getIntent().getExtras(); //get the extras
        String methodName = extras.getString("methodName"); //assign the extras to local variables

        if(methodName != null && methodName.equals("turn_send_switch_off"))
        {
            sendSwitch.setChecked(false);
        }
        //else if(**other actions that may need to be performed can go here**)
    }

Thank you very much for any help!!!

Answer 1

Usually if you have to force a single instance of the app, you should avoid putting android:launchMode="singleInstance" on each activity seeing as it would try to launch an instance for each activity.

Removing the launchMode from everything except the application should ensure that only the application runs in a single instance, although what @Shaishav said is true, most of the time you can let android deal with the lifecycle of an application by not setting the launchMode, unless you have a real need to ensure only one instance is running at a time.