android - How to interpret Logcat

Question

Can anyone tell me how I should read the errors in Logcat? I'd like to understand where my problem is.

At the moment, I tried to read it but can't find the cause of the crash.

Here's the Logcat I don't understand:

05-18 18:29:44.160: ERROR/AndroidRuntime(2145): FATAL EXCEPTION: main
05-18 18:29:44.160: ERROR/AndroidRuntime(2145): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.paad.whereami/com.paad.whereami.WhereAmI}: java.lang.NullPointerException
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.os.Looper.loop(Looper.java:130)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.app.ActivityThread.main(ActivityThread.java:3683)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at java.lang.reflect.Method.invokeNative(Native Method)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at java.lang.reflect.Method.invoke(Method.java:507)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at dalvik.system.NativeStart.main(Native Method)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145): Caused by: java.lang.NullPointerException
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at com.paad.whereami.WhereAmI.updateWithNewLocation(WhereAmI.java:290)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at com.paad.whereami.WhereAmI.onCreate(WhereAmI.java:216)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-18 18:29:44.160: ERROR/AndroidRuntime(2145):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)

Answer 1

The second "part" of your log is going to be what is important for you in this instance.

Caused by: java.lang.NullPointerException

This means that somewhere in your code something is set to null and you are trying to use it as though it isn't.

The next few lines tell you where in your code you can find the error.

at com.paad.whereami.WhereAmI.updateWithNewLocation(WhereAmI.java:290)
at com.paad.whereami.WhereAmI.onCreate(WhereAmI.java:216)

This should mean that you have a method named updateWithNewLocation that you are calling from onCreate at line 216. The error is coming from inside this method at line 290. Take a look at line 290 in your code. Whatever you are trying to do on that line is causing the exception because something is null that shouldn't be.