此Google Play崩溃报告是什么意思？

Question

I am starting game dev. I have been learning Game Maker studio for a while now.

I published my first game to Google Play. After ~1000 downloads I've gotten a few crash reports from a device HTC M9 only:

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.contains(java.lang.CharSequence)' on a null object reference
    at com.jessesopanen.Little_Economist.Gamepad.iCadeDeviceName(Gamepad.java:124)
    at com.jessesopanen.Little_Economist.Gamepad.EnumerateDevices(Gamepad.java:332)
    at com.jessesopanen.Little_Economist.RunnerActivity.doSetup(RunnerActivity.java:541)
    at com.jessesopanen.Little_Economist.DemoRenderer$2.run(DemoRenderer.java:574)
    at android.os.Handler.handleCallback(Handler.java:739)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:168)
    at android.app.ActivityThread.main(ActivityThread.java:5845)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:797)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:687)

What's wrong with my game's code or is the problem with HTC M9? I have tested my game with various devices and it works fine.

I don't understand what that crash report means if someone could help me out?

Answer 1

this report is just here to tell you that someone of your users have a problem with your app and the report give you the stack trace of the problem

Your problem seems come to a java null pointer exception at line 124 this is a very generic error so read your code test it again and good luck ;)

Answer 2

at com.jessesopanen.Little_Economist.Gamepad.iCadeDeviceName(Gamepad.java:124)

===> begin by testing

if(myObject != is_undefined)
{

    //your code

}