How to crash an Android app programmatically?

Question

I want to test out crash report using acra but the first step is I need to simulate a fatal crash in Android using code.

Any idea?

Answer 1

in addition to @vinnet-shukla answer:

"OR simply throw an uncaught exception"

throwing uncaught exception to do a crash is bad idea as the exception could by caught somwhere higher in the stack - especially when whe don't know where we are right now :)

more ellegant way is to use ERROR

An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch. Most such errors are abnormal conditions. The ThreadDeath error, though a "normal" condition, is also a subclass of Error because most applications should not try to catch it.

so we could make our own Error subclass and use it:

/*
 * usage:
 * 
 *   CrashError.doCrash(); 
 *
 */
public class CrashError extends Error {

    public CrashError() { 
        this("simulated crash");
    }

    public CrashError(String msg) {
        super(msg);
    }

    public static void doCrash() {
        throw new CrashError();
    }

}

but if we talk about other possibilities we could also a throw checked exception :)

this will also be a lesson how we could RETHROW CHECKED EXCEPTION :) with other way than use of sun.misc.Unsafe especially when the class is not available in VM implementation

@SuppressWarnings("unchecked")
public static <E extends Throwable> void throwAnyT(Throwable e) throws E {
    throw (E) e;
}

public static void throwUnchecked(Throwable e) {
    throwAny(e);
    // should never get there.
    throw new InternalError();
}

public static void crash() {
    throwUnchecked(new java.io.IOException("simulated crash"));
}

in addition to @audric answer:

"You can't throw null"

yes you can :) it's exactly what you are doing in your example and yes it could get undetectable if the catch block will not use Throwable - the NPX will never be thrown and simply there will be normal flow when code will still execute and yes i'll have seen this and experienced by myself :) on ANDROID DALVIK

and what about..? maybe it could fulfill your needs?

java specific (also in android):

- Runtime.getRuntime().exit(int);
- System.exit(int);
- Runtime.getRuntime().halt(int);

android specific:

- android.os.Process.killProcess(int);
- android.os.Process.killProcessQuiet(int);
- android.os.Process.sendSignal(int,int);
- android.system.Os.kill(int);

Answer 2

Use the following code:

String xyz=null;
system.out.println(xyz);

Answer 3

A very simple approach... and is very important to understand that why it happened.

Try initiating a variable in onCreate() before the setContentView() method, then use it to call a method or variable or try registering it to some listener..

Eg:

Button b;

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        b = (Button)findViewById(R.id.butt);
        b.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {


        }
    });
        setContentView(R.layout.main);


    }

This crashed, because before setContentView() none of the components/view in the main.xml layout got their ids.

Answer 4

Simply create in your main.xml a button like this:

 <Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:onClick="crash"
    android:text="Crash me" />

then run your app and click for crash

Answer 5

If you are using firebase crashlytics, then there is a very easy way to do this. Mentioned in their document also.

val crashlytics = FirebaseCrashlytics.getInstance()
crashlytics.log("my message")

Answer 6

you can crash with a simple null point exception.

 throw new NullPointerException();