CODEWITHSUNDEEP
androidandroid-screen-pinning
Kevin Krumwiede
Kevin Krumwiede

Reputation: 10308

Method to test whether the current task is locked?

I'm playing around with the task locking API on a Nexus 4 running Android 5.0.1. My device owner app consists of two buttons: "Lock" and "Unlock", which simply call startLockTask() and stopLockTask(). That's really all there is to it, but since some people insist on seeing the boilerplate:

public class MainActivity extends Activity {    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.lockButton).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startLockTask();
            }           
        });

        findViewById(R.id.unlockButton).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                stopLockTask();
            }           
        });
    }
}

Pressing the "Lock" button when the task is already locked is harmless. But if I press the "Unlock" button when the task is not locked, I get a NPE:

02-12 22:58:11.942: E/AndroidRuntime(12888): java.lang.NullPointerException: Attempt to read from field 'android.content.Intent com.android.server.am.TaskRecord.intent' on a null object reference
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.os.Parcel.readException(Parcel.java:1546)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.os.Parcel.readException(Parcel.java:1493)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.app.ActivityManagerProxy.stopLockTaskMode(ActivityManagerNative.java:5245)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.app.Activity.stopLockTask(Activity.java:6179)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at com.chalcodes.kiosk.MainActivity$2.onClick(MainActivity.java:44)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.view.View.performClick(View.java:4756)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.view.View$PerformClick.run(View.java:19749)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.os.Handler.handleCallback(Handler.java:739)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.os.Handler.dispatchMessage(Handler.java:95)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.os.Looper.loop(Looper.java:135)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at android.app.ActivityThread.main(ActivityThread.java:5221)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at java.lang.reflect.Method.invoke(Native Method)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at java.lang.reflect.Method.invoke(Method.java:372)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
02-12 22:58:11.942: E/AndroidRuntime(12888):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Is there a method somewhere to test whether the current task is locked?

This is kind of like how unregisterReceiver(...) explodes if you try to unregister a receiver that isn't registered. I think it's a poorly-behaved API that forces you to keep track of its internal state for it. But stopLockTask() is even worse, because whereas you'd normally unregister your receivers when your activity is paused, you would not normally unlock your task. So the next activity is created locked, but it has no way to know it's locked. So you basically have to pass the locked state around in intents and saved instance bundles. Or else just surround every call to stopLockTask() with an ugly try/catch...

Am I making any sense here?

Edit: Created issue #150089.

Upvotes: 8

Views: 3536

Answers (2)

Vikasdeep Singh
Vikasdeep Singh

Reputation: 21766

Here is method to check current state of current task if locked or not in case of screen pinning:

!mActivityManager.isInLockTaskMode()

For more information visit this link: http://developer.android.com/reference/android/app/ActivityManager.html#isInLockTaskMode%28%29

Upvotes: 7

Victor Viola
Victor Viola

Reputation: 585

You need to implement the other methods of the lifecycle (OnResume, OnStop and so on).

Put your logic to unlock the Application inside other method which you'll find out which one is better according to your expected behaviour. Check it out this [link].1

Upvotes: -2

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