Develop Reference

How to stop the MainActivity from being called first?

In my AndroidManifest.xml file, I have two activities:
<activity android:name=".activities.LoginActivity"/>
<activity android:name=".activities.MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
According to the logic of my app, if I'm logged in, I'm redirected directly to the MainActivity, otherwise to the LoginActivity. First time I'm opening the app, LoginActivity is opened but in the background MainActivity is also called. How stop this from happening? But without making LoginActivity as the main activity?

The solution I always adopt is to create a third Activity SplashScreenActivity
<activity
android:name=".activities.SplashScreenActivity"
android:theme="#style/SplashTheme">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
This is nothing more than a Loading Activity where you can instantiate all the stuff you need across application and where you can make this logic.
You can, for example, call this in your SplashActivity's OnCreate:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(/*logics to see if user is logged*/) {
startActivity(SplashScreenActivity.this, MainActivity.class);
}
else {
startActivity(SplashScreenActivity.this, LoginActivity.class);
}
finish(); //finish the splash activity.
}
Another little trick :)
Link from PPartisan in comment: How to implement SplashScreen
I always make this activity Layout-less so that you don't have that annoying "black screen flash" when you first launch your application. In order to do that, as you can see, I specified a theme in that activity's manifest where I simply set this:
<style name="SplashTheme" parent="AppTheme">
<item name="android:windowBackground">#drawable/background_splash</item>
</style>
where that resource is nothing more than a drawable with a background (white background and logo in center, for example).
That way you won't have that black flash when you run your application.
Good luck!

You should move the following code to your login activity but LoginActivity will be the main activity:
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
You can also use one activity with fragments inside and choose which fragment to display to the user according to the login status. See https://developer.android.com/guide/components/fragments
Finally, as mentioned in comments, you can create a splash screen that check if the user is already logged in. But here again, the splash screen will be your main activity. See https://android.jlelse.eu/right-way-to-create-splash-screen-on-android-e7f1709ba154
Best

Close/Kill Android application from recent application on soft key press

I have a overlay view over all apps. I want to close the overlay view from screen on soft key press (home, back and recent). I have a transparent activity with no content which is starting a service having overlay view.
public class SampleOverlayShowActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
startService(new Intent(this, SampleOverlayService.class));
}
#Override
protected void onPause() {
SampleOverlayService.stop();
finish();
super.onPause();
}
}
Inside manifest
<activity
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:name="SampleOverlayShowActivity"
android:excludeFromRecents="true"
android:theme="#android:style/Theme.Dialog" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Everything is working fine expect recent apps. Activity still show up on recent application button press. It got removes when I again press recent application button.

This should be much simpler than trying to override soft key behaviour to do clean up. Instead make sure the activity is launched so that it has no recents trace. From the manifest that means adding noHistory and excludeFromRecents
<activity android:excludeFromRecents="true"
android:noHistory="true"
android:name=".."
...>
<intent-filter>
...
</intent-filter>
</activity>
Note that android:excludeFromRecents works for the task only, so you probably want to make sure that activity is a new task too, using the appropriate flags (android:launchMode="singleTask")

Implement Home Button in custom Launcher

I've written a custom Launcher and it works pretty nice. The Launcher has some pages filled with applications. I want to implement, that the variable that represents the page number is set to 0, if the homebutton is pressed. So if you are on a different page of the launcher and press the homebutton, you enter the starting page.
I've searched a lot, but couldn't find an answer that worked for me.
I've set the app as an launcher in the manifest.
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
Is it possible to achieve this? Just change the value of one variable, if the home button is pressed and leave the rest of the home button, as it is.

For everybody who want to do the same thing. that's the way i solved it:
I added the following to the manifest:
<activity
android:launchMode="singleTask"
android:clearTaskOnLaunch="true"
android:stateNotNeeded="true">
and wrote this into the java activity:
#Override
protected void onNewIntent(Intent intent) {
super.onNewIntent(intent);
if (Intent.ACTION_MAIN.equals(intent.getAction())) {
final boolean alreadyOnHome =
((intent.getFlags() & Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT)
!= Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT);
if (alreadyOnHome) {
Log.d("whatever", "Home pressed");
}
}
}
I got it from here: CyanogenMod trebuchet

Want to launch another activity on start up page without using any listener?

Example I have a java class that has sliding menu code which the java name is Leftandright.java.
Then I have a Main_Activity, but without any listener I want the Application to launch at the LeftandRight.java page. How do I do that?

You can set the starting activity in manifest file, AndroidManifest.xml, by declaring that Activity as a main activity.
<activity
android:name="com.package.LeftandRight" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Or, you can add this code in Main_Activity.java (although this is a VERY BAD approach, do not use unless you know what you're doing)
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
startActivity(new Intent(this, LeftandRight.class));
}

Android custom launcher (Like toddler lock)

I am making a children's app and I would like to add a child lock to it, just like the one on the app called "Toddler lock". Toddler lock asks you to set the default launcher when the lock is turned on which allows the home button to be disabled.
How would I do this?

Ok so ive got a rough working example here:
Create two activities and two layouts, in the main layout place a normal button. The other layout can just have a blank <LinearLayout>.
This is what my manifest looks like:
<activity
android:name=".MainActivity"
android:label="#string/title_activity_main"
android:launchMode="singleTop">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".secondact"
android:label="#string/secondtitle">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.HOME" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
Notice <category android:name="android.intent.category.HOME" /> in second activity.
Here is the code from my main activity:
#Override
public void onResume()
{
super.onResume();
Button btn = (Button)findViewById(R.id.startBtn);
btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent startMain = new Intent(Intent.ACTION_MAIN, null);
startMain.addCategory(Intent.CATEGORY_HOME);
startActivity(startMain);
}
});
}
And in my second activity i have:
#Override
public void startActivity(Intent intent)
{
super.startActivity(intent);
}
When i click the startbtn i get the dialog that you are talking about and you get to chooose launcher or the secondactivity, and select always use. The back button still gets you home, but hopefully this helps. This question might help you further: Disable home button in android toddler app?