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Newbie learning sprites in android java

wayne ferguson
Greenhorn

Joined: Feb 22, 2013
Posts: 4
I am currently learning how to develop apps and games in java for android devices. My problem is I have taken the tutorial of the android developers website on how to draw sprites. I have imported there source into eclipse and just changed the image to mine. all works great. But I have created my own app and moved the code into my version. but for some reason it just crashes. any help appreciated. I have attached the orig code (walking Elaine) to import into eclipse and my code (Ship Shapes)
Ulf Dittmer
Marshal

Joined: Mar 22, 2005
Posts: 42634
    
  65
The first step always is to check the logcat output; if an app crashes, there will be an exception stack trace in there that should point you in the right direction.

By the way, you didn't attach anything (not that you could - attachments are limited to images.)


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wayne ferguson
Greenhorn

Joined: Feb 22, 2013
Posts: 4
Ill post my code and the logcat error when I get back in bout an hour. But I'm very confused as both sets of code are identical so don't get y it crashing lol
Ulf Dittmer
Marshal

Joined: Mar 22, 2005
Posts: 42634
    
  65
That's where the stack trace comes in :-)
wayne ferguson
Greenhorn

Joined: Feb 22, 2013
Posts: 4
This is my logcat can you please explain how I find the error from this thanks.

02-22 12:50:16.260: D/dalvikvm(272): newInstance failed: no <init>()
02-22 12:50:16.260: D/AndroidRuntime(272): Shutting down VM
02-22 12:50:16.270: W/dalvikvm(272): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
02-22 12:50:16.300: E/AndroidRuntime(272): FATAL EXCEPTION: main
02-22 12:50:16.300: E/AndroidRuntime(272): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.appzheaven.shipshapes/com.appzheaven.shipshapes.MainGameActivity}: java.lang.InstantiationException: com.appzheaven.shipshapes.MainGameActivity
02-22 12:50:16.300: E/AndroidRuntime(272): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.os.Handler.dispatchMessage(Handler.java:99)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.os.Looper.loop(Looper.java:123)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.app.ActivityThread.main(ActivityThread.java:4627)
02-22 12:50:16.300: E/AndroidRuntime(272): at java.lang.reflect.Method.invokeNative(Native Method)
02-22 12:50:16.300: E/AndroidRuntime(272): at java.lang.reflect.Method.invoke(Method.java:521)
02-22 12:50:16.300: E/AndroidRuntime(272): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-22 12:50:16.300: E/AndroidRuntime(272): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-22 12:50:16.300: E/AndroidRuntime(272): at dalvik.system.NativeStart.main(Native Method)
02-22 12:50:16.300: E/AndroidRuntime(272): Caused by: java.lang.InstantiationException: com.appzheaven.shipshapes.MainGameActivity
02-22 12:50:16.300: E/AndroidRuntime(272): at java.lang.Class.newInstanceImpl(Native Method)
02-22 12:50:16.300: E/AndroidRuntime(272): at java.lang.Class.newInstance(Class.java:1429)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
02-22 12:50:16.300: E/AndroidRuntime(272): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)

here is my code

MainGameActivity.java


Ulf Dittmer
Marshal

Joined: Mar 22, 2005
Posts: 42634
    
  65
02-22 12:50:16.260: D/dalvikvm(272): newInstance failed: no <init>()

02-22 12:50:16.300: E/AndroidRuntime(272): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.appzheaven.shipshapes/com.appzheaven.shipshapes.MainGameActivity}

This means that the MainGameActivity can't be instantiated because it doesn't have a no-argument constructor. Activities shouldn't have a constructor, so that the compiler will insert the default constructor that is missing here. Any initialization should then be done in the onCreate method.
 
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