I'm tinkering around with android on Netbeans and did a simple math application. Somewhere along the way the application suddenly force closes as soon as it opens(On the emulator)... I tried commenting all the code in the class that hosts the main activity but to no avail. Since it doesn't give me a specific error message, I feel kind of lost.
Any reason why this is happening?
Here is the layout file as requested:
<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView android:id="@+id/result"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text=""/>
<LinearLayout android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<TextView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/number" />
<EditText android:id="@+id/n"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:numeric="decimal"/>
<Button android:id="@+id/calc"
android:text="@string/calculate"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>
As suggested I checked logcat and this is the list of errors
E/AndroidRuntime( 881): Uncaught handler: thread main exiting due to uncaught exception
E/AndroidRuntime( 881): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{org.me.mathdroid/org.me.mathdroid.MainActivity}: java.lang.NullPointerException
E/AndroidRuntime( 881): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2324)
E/AndroidRuntime( 881): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417)
E/AndroidRuntime( 881): at android.app.ActivityThread.access$2100(ActivityThread.java:116)
E/AndroidRuntime( 881): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
E/AndroidRuntime( 881): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime( 881): at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime( 881): at android.app.ActivityThread.main(ActivityThread.java:4203)
E/AndroidRuntime( 881): at java.lang.reflect.Method.invokeNative(NativeMethod)
E/AndroidRuntime( 881): at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime( 881): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
E/AndroidRuntime( 881): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
E/AndroidRuntime( 881): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime( 881): Caused by: java.lang.NullPointerException
E/AndroidRuntime( 881): at android.app.Activity.findViewById(Activity.java:1610)
E/AndroidRuntime( 881): at org.me.mathdroid.MainActivity.<init>(MainActivity.java:22)
E/AndroidRuntime( 881): at java.lang.Class.newInstanceImpl(Native Method)
E/AndroidRuntime( 881): at java.lang.Class.newInstance(Class.java:1472)
E/AndroidRuntime( 881): at android.app.Instrumentation.newActivity(Instrumentation.java:1097)
E/AndroidRuntime( 881): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2316)
E/AndroidRuntime( 881): ... 11 more
Is this on a phone, or in the emulator? First place I'd look is in the logs. In Eclipse go to Window > Show View > Other... > Android > LogCat.
You can add your own debug logging messages in your code by
Log.d("Debug", "Informative Log Message.");
It would also be helpful if you could post your code here. Post the minimum working code example that exhibits the buggy behavior.
I have figured out what the problem was, in the main activity I was setting an Edittext and TextView objects with the ones in the R class, before setting the contentView. Sorry for the trouble.
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