I have been going through Tutorial 12 of Busy Coders Guide version 5.1.
When I run the emulator the app keeps crashing during startup. I am not clear on what to look for in my logcat file. Can you please help me understand what I need to look for. Thanks.
I searched and didn't see any other posts regarding Tutorial 12. If there is can you please point me in the right direction. Thanks.
10-01 16:01:11.921: D/dalvikvm(1397): GC_FOR_ALLOC freed 103K, 8%
free 2808K/3028K, paused 37ms, total 39ms 10-01 16:01:11.921:
I/dalvikvm-heap(1397): Grow heap (frag case) to 3.460MB for
635812-byte allocation 10-01 16:01:12.041: D/dalvikvm(1397):
GC_FOR_ALLOC freed 3K, 7% free 3426K/3652K, paused 114ms, total 114ms
10-01 16:01:12.291: D/gralloc_goldfish(1397): Emulator without GPU
emulation detected. 10-01 16:01:12.491: D/AndroidRuntime(1397):
Shutting down VM 10-01 16:01:12.511: W/dalvikvm(1397): threadid=1:
thread exiting with uncaught exception (group=0x41465700) 10-01
16:01:12.581: E/AndroidRuntime(1397): FATAL EXCEPTION: main 10-01
16:01:12.581: E/AndroidRuntime(1397): java.lang.NullPointerException
10-01 16:01:12.581: E/AndroidRuntime(1397): at
com.commonsware.empublite.BookContents.getChapterCount(BookContents.java:16)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
com.commonsware.empublite.ContentsAdapter.getCount(ContentsAdapter.java:26)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
android.support.v4.view.ViewPager.setAdapter(ViewPager.java:434) 10-01
16:01:12.581: E/AndroidRuntime(1397): at
com.commonsware.empublite.EmPubLiteActivity.setupPager(EmPubLiteActivity.java:70)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
com.commonsware.empublite.ModelFragment.deliverModel(ModelFragment.java:29)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
com.commonsware.empublite.ModelFragment.access$2(ModelFragment.java:27)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
com.commonsware.empublite.ModelFragment$ContentsLoadTask.onPostExecute(ModelFragment.java:82)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
com.commonsware.empublite.ModelFragment$ContentsLoadTask.onPostExecute(ModelFragment.java:1)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
android.os.AsyncTask.finish(AsyncTask.java:631) 10-01 16:01:12.581:
E/AndroidRuntime(1397): at
android.os.AsyncTask.access$600(AsyncTask.java:177) 10-01
16:01:12.581: E/AndroidRuntime(1397): at
android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
android.os.Handler.dispatchMessage(Handler.java:99) 10-01
16:01:12.581: E/AndroidRuntime(1397): at
android.os.Looper.loop(Looper.java:137) 10-01 16:01:12.581:
E/AndroidRuntime(1397): at
android.app.ActivityThread.main(ActivityThread.java:5103) 10-01
16:01:12.581: E/AndroidRuntime(1397): at
java.lang.reflect.Method.invokeNative(Native Method) 10-01
16:01:12.581: E/AndroidRuntime(1397): at
java.lang.reflect.Method.invoke(Method.java:525) 10-01 16:01:12.581:
E/AndroidRuntime(1397): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-01 16:01:12.581: E/AndroidRuntime(1397): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 10-01
16:01:12.581: E/AndroidRuntime(1397): at
dalvik.system.NativeStart.main(Native Method)
I am not clear on what to look for in my logcat file
That would be the exception and line where you are crashing:
10-01 16:01:12.581: E/AndroidRuntime(1397): FATAL EXCEPTION: main
10-01 16:01:12.581: E/AndroidRuntime(1397): java.lang.NullPointerException
10-01 16:01:12.581: E/AndroidRuntime(1397): at com.commonsware.empublite.BookContents.getChapterCount(BookContents.java:16)
Hence, you are crashing in line 16 of BookContents.java, in the getChapterCount() method of the BookContents class.
That method should look like:
int getChapterCount() {
return(chapters.length());
}
That indicates that either:
You are missing the chapters=raw.optJSONArray("chapters"); line in the constructor, or
Your JSON is missing the chapters array
Here is a working implementation of Tutorial 12, including the BookContents class.