Develop Reference

java.io.FileNotFoundException on posting data from Android

I am trying to post data from my android device to server through HTTPS Url, I am getting this error
java.io.FileNotFoundException:https://URL
at com.android.okhttp.internal.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:186)
at com.android.okhttp.internal.http.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:246)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Can anyone help me?

Cannot connect to local XMPP server using aSmack

I am trying connect to a local XMPP server (Vysper) from an Android App using this code:
// ...
ConnectionConfiguration connectionConfig = new ConnectionConfiguration("192.168.1.107", 5222);
// load file from "Pictures" directory from Internal Memory
File file = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
file.mkdirs();
connectionConfig.setSecurityMode(ConnectionConfiguration.SecurityMode.required);
System.setProperty("javax.net.ssl.trustStore", file + "/clientkeystore");
Log.i("Info", file.getAbsolutePath());
XMPPConnection connection = new XMPPTCPConnection(connectionConfig);
SASLAuthentication.supportSASLMechanism("PLAIN", 0);
connection.connect();
//...
This is the stack trace:
01-27 20:41:07.489 3229-3229/ E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.bm.sam, PID: 3229
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3823)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3818)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException: println needs a message
at android.util.Log.println_native(Native Method)
at android.util.Log.e(Log.java:232)
at com.bm.sam.LoginActivity.onClickLoginButton(LoginActivity.java:187)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3818)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
I am using aSmack 4.0.6 and the Android API 19.
Android network permissions and file permissions have been granted:
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
What is wrong?

Your error log says you have a Log.e that is empty, so check that Log first:
Caused by: java.lang.NullPointerException: println needs a message
at android.util.Log.println_native(Native Method)
at android.util.Log.e(Log.java:232)

Android Studio intermittent ClassNotFoundException

I've already read serveral Q&A's from SO and did not found a solution.
My problem is: I run my app from AndroidStudio and get the error bellow, then I run gradlew clean installDebug and code works just fine (outside AS, with NO changes).
I did NOT forgot to include my activity into AndroidManifest.
10-13 13:36:18.261 1457-1457/my.package E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: my.package, PID: 1457
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{my.package/my.package.activity.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "my.package.activity.MainActivity" on path: DexPathList[[zip file "/data/app/my.package-1.apk"],nativeLibraryDirectories=[/data/app-lib/my.package-1, /system/lib]]
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: Didn't find class "my.package.activity.MainActivity" on path: DexPathList[[zip file "/data/app/my.package-1.apk"],nativeLibraryDirectories=[/data/app-lib/my.package-1, /system/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)
I'm using Android Studio 0.8.12 and this is reproducible with real devices and emulator (Genymotion).
EDIT
I've tried both "full path" and "class name only" into my AndroidManifest file to declare activities. And it still doesn't explain (IMHO) why it works via command line with gradle.

Android Studio AVD Emulator non-watch error

I am trying my hand at developing simple apps with the Android Studio and I cannot seem to run even the default app with a blank activity containing the string "Hello World". When I try and run a device on a running Emulator, it gives me an error message and says it the app is not compatible on a watch. I don't know why it would think the emulator is a watch, but I don't know why I cannot emulate an app without changing anything manifest on the simplest AVD provided. Here is an image of the compatibility http://imgur.com/DEWoaON
08-26 16:09:16.500 733-733/com.example.mac.trial3 E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.mac.trial3, PID: 733
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mac.trial3/com.example.mac.trial3.MyActivity}: android.util.AndroidRuntimeException: You cannot combine swipe dismissal and the action bar.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2197)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2258)
at android.app.ActivityThread.access$800(ActivityThread.java:138)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1209)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5026)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.util.AndroidRuntimeException: You cannot combine swipe dismissal and the action bar.
at com.android.internal.policy.impl.PhoneWindow.requestFeature(PhoneWindow.java:275)
at com.android.internal.policy.impl.PhoneWindow.generateLayout(PhoneWindow.java:2872)
at com.android.internal.policy.impl.PhoneWindow.installDecor(PhoneWindow.java:3129)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:303)
at android.app.Activity.setContentView(Activity.java:1930)
at com.example.mac.trial3.MyActivity.onCreate(MyActivity.java:14)
at android.app.Activity.performCreate(Activity.java:5242)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2161)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2258)
            at android.app.ActivityThread.access$800(ActivityThread.java:138)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1209)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5026)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
            at dalvik.system.NativeStart.main(Native Method)

NullPointerException in ContextWrapper.getResources()

I really don't know what's going on with the Android app I'm building. At some point on its development, I started getting it breaking as soon as it starts in the emulator, with the message "Foo stopped". Here is the error log, if anyone could help me:
07-05 21:13:30.063 7647-7647/root.fazerumsom E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: root.fazerumsom, PID: 7647
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{root.fazerumsom/root.fazerumsom.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.content.ContextWrapper.getResources(ContextWrapper.java:89)
at android.view.ContextThemeWrapper.getResources(ContextThemeWrapper.java:78)
at root.fazerumsom.MainActivity.<init>(MainActivity.java:31)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)

You're calling getResources() from a field initializer. Something like
private String mStr = getResources().getString(...);
(or with drawables or other kind of resources).
This is not valid, since the Context isn't set up yet. Move this assignment inside the onCreate() method.

The checked exception java.lang.NullPointerException is thrown when you're trying to use an object without reference,in simple words that means: you're trying to use a object variable without value.
Remember that a variable hold bits, primitive and non-primitive variable do, but the difference is that primitive variable hold the value in bits, but non-primitive variable hold the bits (like a direction) to access the object in memory, and when it's not being used anymore GGC (Garbage Colector) kills it.