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¿How can i launch my app or an activity in background?

How can I start an activity when my app is in background? I mean, when it has not been destroyed? I have tried with IntentService and nothing, I just want to make a StartActivity to launch my MainActivity in the background.

Your service needs to be a foreground service.
Here is how.
First in your Manifest.xml file.
Request for permission
<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
......
<!-- Your Service-->
<service
android:name=".MyService"
android:enabled="true"
android:exported="true"
android:permission="android.permission.FOREGROUND_SERVICE"/>
Start your service with:
startForegroundService(Intent(this, MyService::class.java))
Then in your service display the foreground notification(usually in the onStartCommand):
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
val ncCompat = NotificationChannelCompat.Builder("your.own.id.here", NotificationManagerCompat.IMPORTANCE_DEFAULT).setName("Important").build()
NotificationManagerCompat.from(baseContext).createNotificationChannel(ncCompat)
startForeground("your.notification.id.goes.here".hashCode(), NotificationCompat.Builder(baseContext, nmCompat.id).setContentTitle("My Foreground Service").setContentText("Running Service").build())
return super.onStartCommand(intent, flags, startId)
}
Then your can start an activity(for example: see below)
val intent = Intent(application, MainActivity2::class.java)
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_TASK_ON_HOME)
intent.addFlags(Intent.FLAG_FROM_BACKGROUND)
startActivity(intent)
Android may complain that your activity needs to inherit theme from Theme.AppCompat and you may also have difficulties loading an xml layout.
I believe your can work around those. Apart from that your are good to go.
And also note that i only tested it on Android 10 and below.

Right-click on the project, Select New >> Service >> Service and add the following to MyServices.java
public class MyService extends Service {
public MyService() {
}
#Override
public int onStartCommand(Intent intent, int flags, int startId){
onTaskRemoved(intent);
Toast.makeText(getApplicationContext(),"This is a Service running in Background",
Toast.LENGTH_SHORT).show();
return START_STICKY;
}
#Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
#Override
public void onTaskRemoved(Intent rootIntent) {
Intent restartServiceIntent = new Intent(getApplicationContext(),this.getClass());
restartServiceIntent.setPackage(getPackageName());
startService(restartServiceIntent);
super.onTaskRemoved(rootIntent);
}
}
Add the following code to res/layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
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:text="Click here"
android:textStyle="bold"
android:textSize="16sp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true" />
</RelativeLayout>
Add the following code to src/MainActivity.java
public class MainActivity extends AppCompatActivity {
Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startService(new Intent(getApplicationContext(),MyService.class));
}
});
}
}
Add the following code to androidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="app.com.sample">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<service
android:name=".MyService"
android:enabled="true"
android:exported="true"></service>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Let's try to run your application.
Click on the Click here button to start background services.

Splash screen alpha animation not working

So I have an app that currently has two Activities. A SplashScreenActivity and a MainActivity. The transition between the two activities works just fine but the problem lies in the SplashScreenActivity itself. In it, there is a single ImageView that is supposed to be initially invisible and then fade in. But instead the image remains invisible the entire time. Please help. Here's the code:
The SplashScreenActivity:
package com.degioncloud;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.ImageView;
public class SplashScreenActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splashscreen);
ImageView logo = (ImageView) findViewById(R.id.iv_logo);
logo.setImageAlpha(0);
logo.animate().alpha(1f).setDuration(1200).withEndAction(new Runnable() {
#Override
public void run() {
Intent i = new Intent(SplashScreenActivity.this, MainActivity.class);
startActivity(i);
overridePendingTransition(android.R.anim.fade_in,android.R.anim.fade_out);
finish();
}
});
}
}
The XML of the SplashScreenActivity:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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=".SplashScreenActivity">
<ImageView
android:id="#+id/iv_logo"
android:layout_width="200dp"
android:layout_height="200dp"
android:src="#mipmap/ic_launcher"
android:layout_centerInParent="true" />
</RelativeLayout>
My Manifest file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.degioncloud">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/Theme.DegionCloud">
<activity android:name=".MainActivity" />
<activity android:name=".SplashScreenActivity"
android:theme="#style/SplashScreenTheme">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
The MainActivty is empty so I don't see a need to share that but if you need any other file then let me know and I will send a copy.

You need to call start() for the animation to begin:
logo.animate().alpha(1f).setDuration(1200).withEndAction(new Runnable() {
#Override
public void run() {
Intent i = new Intent(SplashScreenActivity.this, MainActivity.class);
startActivity(i);
overridePendingTransition(android.R.anim.fade_in,android.R.anim.fade_out);
finish();
}
}).start();

Could not identify launch Activity: Default Activity wasn't found

I'm new to Android and I have tried to create a new View.
But I get this error on run
Could not identify launch Activity: Default Activity not found
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">
<com.bamlineapps.dungeonexplorer.DungeonExplorer xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/dungeonView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
</com.bamlineapps.dungeonexplorer.DungeonExplorer>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
Here is my android manifest as I think that the error comes from here:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.bamlineapps.dungeonexplorer">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme"
tools:ignore="GoogleAppIndexingWarning">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

Your manifest file must list all activities you want to use and the one you want to be your entry point needs to have right intent filter:
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

I'm guessing that you've forgot to
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas); // <- this line
// Your code here
}
And I can only guess because there's some important data missing in the question - Could you please attach the crash Logs/errors printed on console on the question?
Update
Try null checking your variables and initializing stuff in the constructor of your class like so:
public class YourView extends ImageView { // I don't know; provide more info
private Bitmap chibiSprite;
public YourView(Context context) {
super(context);
chibiSprite = BitmapFactory.decodeResource(getResources(), R.drawable.chibi_sprite);
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
if(canvas != null)
drawCharacter(canvas);
}
public void drawCharacter(Canvas canvas) {
// Customize these three
float location_x = 100F;
float location_y = 100F;
Paint custom_paint = null;
canvas.drawBitmap(chibiSprite, location_x, location_y, custom_paint);
}
}

How to avoid remaining white screen on webview android app

activity_main
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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="com.google.httpwww.google.MainActivity">
<WebView
android:id="#+id/webView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerHorizontal="true"
tools:layout_editor_absoluteX="8dp"
tools:layout_editor_absoluteY="8dp" />
</RelativeLayout>
MainActivity.java
package com.google.httpwww.google;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.os.Bundle;
import android.webkit.WebViewClient;
public class MainActivity extends AppCompatActivity {
WebView webview;
#Override
public void onBackPressed() {
if (webview.canGoBack()) {
webview.goBack();
} else {
super.onBackPressed();
}
}
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
webview = (WebView) findViewById(R.id.webView);
WebSettings webSettings = webview.getSettings();
webSettings.setJavaScriptEnabled(true);
webview.setWebViewClient(new WebViewClient());
webview.loadUrl("http://www.google.com/");
}
}
AndroidManifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.google.httpwww.google">
<uses-permission android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
As I run the app it gives white blank page with header as name of app. On internet most of case is based on at the begining of app there is white page but in my case it's remaining. Is there any idea what I am doing wrong?
P.S: I am new about android apps what I need just a app which will show my website.

Getting AdView to work

I am developing a game in libgdx. I read the official docs and tried to integrate MobClix Ads in my App but eclipse can't resolve this constructor for ADView class: (for Example):
AdView ad = new AdView(this, AdSize.BANNER, "a14d91b10f12454");
This line of code give me an error.
Maybe my import is not correct? I import this:
import com.google.android.gms.ads.AdSize;
import com.google.android.gms.ads.AdView;
And the same for:
adView.loadAd(new AdRequest());
I tried to search for an answer but I coudn't find, Does somone know how to resolve this?
Sorry for my poor english.

Put this code to mainactivity
import android.app.Activity;
import android.os.Bundle;
import com.startapp.android.publish.StartAppAd;
public class MainActivity extends Activity {
private StartAppAd add = new StartAppAd(this);
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
StartAppAd.init(this, "105158220", "205151606");
//StartAppSearch.init(this, "105158220", "205151606");
setContentView(R.layout.activity_main);
if(add.isReady())
{
add.showAd(); // show the ad
add.loadAd();
}
//a.loadAd(AdMode.FULLPAGE);
}
#Override
public void onResume(){
super.onResume();
add.onResume();
}
#Override
public void onBackPressed() {
add.onBackPressed();
super.onBackPressed();
}
#Override
public void onPause() {
super.onPause();
add.onPause();
}
}
put this into your xml file
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<com.startapp.android.publish.banner.banner3d.Banner3D
android:id="#+id/startApp3DBanner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"/>
</RelativeLayout>
put this into ur Manifest file
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<uses-permission android:name="android.permission.GET_TASKS" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.start_up_app.MainActivity"
android:configChanges="keyboard|keyboardHidden|orientation"
android:label="#string/app_name"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.startapp.android.publish.list3d.List3DActivity"
android:taskAffinity="com.example.start_up_app.AppWall"
android:theme="#android:style/Theme" />
<activity
android:name="com.startapp.android.publish.AppWallActivity"
android:configChanges="orientation|keyboardHidden"
android:taskAffinity="com.example.start_up_app.AppWall"
android:theme="#android:style/Theme.Translucent" />
</application>
</manifest>
for you have to use StartAppCommon-1.0.1.jar and StartAppInApp-2.0.7.jar