Database connection on android studio using java.

[Darius Boteand]

Hello!

I am literally following a tutorial word to word from this link - Youtube - MySQL & Android Studio JDBC
What I am trying to do is connect to my database as you might have guessed, and retrieve a simple text from it.

My issue is that once I press on the button, the application just crashes?  I have no idea for what reason.
The only code that changes is the connection part (with my credentials) and what I need to printout. Apart from that, everything is identical...

Could someone help me overcome this issue please?

[Darius Boteand]

If this can help anyone understand the reason, this is the output I have in the logcat:

2021-01-07 15:10:10.390 22070-22070/? I/example.test_0: Not late-enabling -Xcheck:jni (already on)
2021-01-07 15:10:10.426 22070-22070/? I/example.test_0: Unquickening 12 vdex files!
2021-01-07 15:10:10.428 22070-22070/? W/example.test_0: Unexpected CPU variant for X86 using defaults: x86
2021-01-07 15:10:11.080 22070-22070/com.example.test_09 D/NetworkSecurityConfig: No Network Security Config specified, using platform default
2021-01-07 15:10:11.082 22070-22070/com.example.test_09 D/NetworkSecurityConfig: No Network Security Config specified, using platform default
2021-01-07 15:10:11.110 22070-22094/com.example.test_09 D/libEGL: loaded /vendor/lib/egl/libEGL_emulation.so
2021-01-07 15:10:11.114 22070-22094/com.example.test_09 D/libEGL: loaded /vendor/lib/egl/libGLESv1_CM_emulation.so
2021-01-07 15:10:11.124 22070-22094/com.example.test_09 D/libEGL: loaded /vendor/lib/egl/libGLESv2_emulation.so
2021-01-07 15:10:11.343 22070-22070/com.example.test_09 W/example.test_0: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
2021-01-07 15:10:11.343 22070-22070/com.example.test_09 W/example.test_0: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
2021-01-07 15:10:11.512 22070-22092/com.example.test_09 D/HostConnection: HostConnection::get() New Host Connection established 0xee7eafd0, tid 22092
2021-01-07 15:10:11.546 22070-22092/com.example.test_09 D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_gles_max_version_3_0
2021-01-07 15:10:11.556 22070-22092/com.example.test_09 W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
2021-01-07 15:10:11.559 22070-22092/com.example.test_09 D/EGL_emulation: eglCreateContext: 0xee7f8320: maj 3 min 0 rcv 3
2021-01-07 15:10:11.562 22070-22092/com.example.test_09 D/EGL_emulation: eglMakeCurrent: 0xee7f8320: ver 3 0 (tinfo 0xeeb38cd0) (first time)
2021-01-07 15:10:11.591 22070-22092/com.example.test_09 I/Gralloc4: mapper 4.x is not supported
2021-01-07 15:10:11.593 22070-22092/com.example.test_09 D/HostConnection: createUnique: call
2021-01-07 15:10:11.594 22070-22092/com.example.test_09 D/HostConnection: HostConnection::get() New Host Connection established 0xee7f8470, tid 22092
2021-01-07 15:10:11.595 22070-22092/com.example.test_09 D/goldfish-address-space: allocate: Ask for block of size 0x100
2021-01-07 15:10:11.626 22070-22092/com.example.test_09 D/goldfish-address-space: allocate: ioctl allocate returned offset 0x3fd4e1000 size 0x2000
2021-01-07 15:10:11.658 22070-22092/com.example.test_09 D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_gles_max_version_3_0
2021-01-07 15:10:15.301 22070-22099/com.example.test_09 W/example.test_0: Accessing hidden method Ljava/lang/invoke/LambdaMetafactory;->metafactory(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodHandle;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite; (blacklist, linking, denied)
2021-01-07 15:10:15.306 22070-22099/com.example.test_09 E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
   Process: com.example.test_09, PID: 22070
   java.lang.RuntimeException: An error occurred while executing doInBackground()
       at android.os.AsyncTask$4.done(AsyncTask.java:415)
       at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)
       at java.util.concurrent.FutureTask.setException(FutureTask.java:252)
       at java.util.concurrent.FutureTask.run(FutureTask.java:271)
       at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:305)
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
       at java.lang.Thread.run(Thread.java:923)
    Caused by: java.lang.NoSuchMethodError: No static method metafactory(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodHandle;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite; in class Ljava/lang/invoke/LambdaMetafactory; or its super classes (declaration of 'java.lang.invoke.LambdaMetafactory' appears in /apex/com.android.art/javalib/core-oj.jar)
       at com.mysql.cj.jdbc.AbandonedConnectionCleanupThread.<clinit>(AbandonedConnectionCleanupThread.java:63)
       at java.lang.Class.classForName(Native Method)
       at java.lang.Class.forName(Class.java:454)
       at java.lang.Class.forName(Class.java:379)
       at com.mysql.cj.jdbc.NonRegisteringDriver.<clinit>(NonRegisteringDriver.java:98)
       at java.lang.Class.classForName(Native Method)
       at java.lang.Class.forName(Class.java:454)
       at java.lang.Class.forName(Class.java:379)
       at com.example.test_09.MainActivity$Task.doInBackground(MainActivity.java:50)
       at com.example.test_09.MainActivity$Task.doInBackground(MainActivity.java:37)
       at android.os.AsyncTask$3.call(AsyncTask.java:394)
       at java.util.concurrent.FutureTask.run(FutureTask.java:266)
       at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:305) 
       at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
       at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
       at java.lang.Thread.run(Thread.java:923) 
2021-01-07 15:10:15.348 22070-22099/com.example.test_09 I/Process: Sending signal. PID: 22070 SIG: 9

[Darius Boteand]

If this can help as well, I do have confirmation that the issue is related with the database connection:
I did not include the class.forname(com.blablabla) and have had an actual output on my phone with the error as i had a textView that would display it on the phone. The error was saying that there was no suitable libraries found for the connection.
But as soon as I have added the line and ran the program, the app would crash straight away once i had press the load button...

[Darius Boteand]

I just tried to follow another tutorial, but I just have the same issue! As soon as I insert the jdbc driver, it just crashes! link
I really don't understand why my android studio doesn't want to use the jdbc driver...

[Tim Moores]

On which Android API version are you running this? The code in question does something with lambdas, and that's supported only in Android versions 8 or newer (Android Oreo).

Also: Android supports JDBC 4.1, so be sure to use the Connector/J 5.1 driver, not the newer Connector/J 8, which is built on top of JDBC 4.2.

Lastly: Android apps should not use JDBC at all. If you need storage on the device, use the Room library. if you need to store something remotely, create a web service as a proxy to the database.

[Darius Boteand]

Thank you for you answer! You see I have been using the latest driver, I didn't know that I wasn't meant to use other than the 5.1 version! this did solve my issue. Thank you very much!