Android Studio app works in emulator but not on a real device

Question

I am new to android programming and have been having a lot of trouble with it. I finally got my app to work in the emulator on both API 23 and 16 my target is API 16. It runs with no problems on the emulators but when I try to use it on my phone (Google Nexus 5 API 23)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:gravity="center"
    android:orientation="vertical"
    android:background="#F44336"
    android:id="@+id/background"
    tools:context="thereisstuffhere.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"
        android:id="@+id/factTextBox"
        android:textSize="25dp"
        android:textColor="#fff"/>
</LinearLayout>


package there is stuff here too;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    TextView factBox;
    LinearLayout bg;
    Facts factHolder = new Facts(this);
    Backgrounds backs = new Backgrounds();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        factBox = (TextView) findViewById(R.id.factTextBox);
        factBox.setText(factHolder.nextFact());
        bg = (LinearLayout) findViewById(R.id.background);
        bg.setBackgroundColor(getResources().getColor(backs.getBackground()));
        bg.setOnTouchListener(new OnSwipeTouchListener(this)
        {
            public void onSwipeTop()
            {
                //Toast.makeText(MainActivity.this, "top", Toast.LENGTH_SHORT).show();
            }
            public void onSwipeRight()
            {
                //Toast.makeText(MainActivity.this, "right", Toast.LENGTH_SHORT).show();
                prev();
            }
            public void onSwipeLeft()
            {
                //Toast.makeText(MainActivity.this, "left", Toast.LENGTH_SHORT).show();
                next();
            }
            public void onSwipeBottom()
            {
                //Toast.makeText(MainActivity.this, "bottom", Toast.LENGTH_SHORT).show();
            }
            public boolean onTouch(View v, MotionEvent event) {
                return gestureDetector.onTouchEvent(event);
            }
        });
    }

    private void next() {
        factBox.setText(factHolder.nextFact());
        bg.setBackgroundColor(getResources().getColor(backs.getBackground()));
    }

    private void prev() {
        factBox.setText(factHolder.prevFact());
        bg.setBackgroundColor(getResources().getColor(backs.getBackground()));
    }

    public void genFact(View view)
    {
        factBox.setText(factHolder.nextFact());
    }

Facts.java just contains a huge list and two functions that return the next or previous string in the list

Backgrounds.java does essentially the same thing only it uses an Integer list and the colors.xml file to store the tags etc

This is my OnTouchListener class:

package stuff be here;

import android.content.Context;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;

public class OnSwipeTouchListener implements OnTouchListener {
    final GestureDetector gestureDetector;

    public OnSwipeTouchListener(Context ctx)
    {
        gestureDetector = new GestureDetector(ctx, new GestureListener());
    }

    @Override
    public boolean onTouch(View view, MotionEvent motionEvent)
    {
        return false;
    }

    private final class GestureListener extends SimpleOnGestureListener{

        private static final int SWIPE_THRESHOLD = 100;
        private static final int SWIPE_VELOCITY_THRESHOLD = 100;

        @Override
        public boolean onDown(MotionEvent e)
        {
            return true;
        }

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
        {
            boolean result = false;
            try{
                float diffY = e2.getY() - e1.getY();
                float diffX = e2.getX() - e1.getX();
                if(Math.abs(diffX) > Math.abs(diffY)){
                    if(Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD){
                        if(diffX > 0){
                            onSwipeRight();
                        }else{
                            onSwipeLeft();
                        }
                    }
                    result = true;
                }
                else if(Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD){
                    if(diffY > 0){
                        onSwipeBottom();
                    }else{
                        onSwipeTop();
                    }
                }
                result = true;
            } catch (Exception exception){
                exception.printStackTrace();
            }
            return result;
        }
    }
    public void onSwipeRight(){}
    public void onSwipeLeft(){}
    public void onSwipeTop(){}
    public void onSwipeBottom(){}
}

I apologise for all of the code but I have been trying to fix this for a while to no avail. I get a lot of errors when I try to run like "Class not found using the boot class loader; no stack trace available" and "Unable to instantiate activity ComponentInf..." I also get some warnings like "ClassLoader referenced unknown path: /data/app/packagenamehere-1/lib/x86_64 and /data/app/packagenamehere-1/lib/arm" even when running in the emulator

Here is my log cat file:

12-16 17:26:25.167 22237-22237/com.ubiquity.sciencefacts I/art: Late-enabling -Xcheck:jni
12-16 17:26:25.197 22237-22243/com.ubiquity.sciencefacts I/art: Ignoring second debugger -- accepting and dropping
12-16 17:26:25.203 22237-22243/com.ubiquity.sciencefacts I/art: Debugger is no longer active
12-16 17:26:25.211 22237-22243/com.ubiquity.sciencefacts W/art: Suspending all threads took: 7.324ms
12-16 17:26:25.235 22237-22237/com.ubiquity.sciencefacts W/System: ClassLoader referenced unknown path: /data/app/com.ubiquity.sciencefacts-2/lib/arm
12-16 17:26:25.248 22237-22237/com.ubiquity.sciencefacts D/AndroidRuntime: Shutting down VM
12-16 17:26:25.254 22237-22237/com.ubiquity.sciencefacts E/AndroidRuntime: FATAL EXCEPTION: main
12-16 17:26:27.065 22237-22237/com.ubiquity.sciencefacts I/Process: Sending signal. PID: 22237 SIG: 9
12-16 17:33:18.574 24986-24986/com.ubiquity.sciencefacts W/System: ClassLoader referenced unknown path: /data/app/com.ubiquity.sciencefacts-1/lib/arm
12-16 17:33:18.662 24986-24986/com.ubiquity.sciencefacts D/AndroidRuntime: Shutting down VM
12-16 17:33:18.673 24986-24986/com.ubiquity.sciencefacts E/AndroidRuntime: FATAL EXCEPTION: main
12-16 17:33:20.800 24986-24986/com.ubiquity.sciencefacts I/Process: Sending signal. PID: 24986 SIG: 9
12-16 17:34:15.668 25845-25845/com.ubiquity.sciencefacts W/System: ClassLoader referenced unknown path: /data/app/com.ubiquity.sciencefacts-1/lib/arm
12-16 17:34:15.687 25845-25845/com.ubiquity.sciencefacts D/AndroidRuntime: Shutting down VM
12-16 17:34:15.693 25845-25845/com.ubiquity.sciencefacts E/AndroidRuntime: FATAL EXCEPTION: main
12-16 18:00:52.080 2640-2640/com.ubiquity.sciencefacts I/art: Not late-enabling -Xcheck:jni (already on)
12-16 18:00:52.142 2640-2640/com.ubiquity.sciencefacts W/System: ClassLoader referenced unknown path: /data/app/com.ubiquity.sciencefacts-1/lib/x86_64
12-16 18:00:52.568 2640-2640/com.ubiquity.sciencefacts W/System: ClassLoader referenced unknown path: /data/app/com.ubiquity.sciencefacts-1/lib/x86_64
12-16 18:00:52.805 2640-2640/com.ubiquity.sciencefacts W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
12-16 18:00:53.993 2640-2646/com.ubiquity.sciencefacts W/art: Suspending all threads took: 633.582ms
12-16 18:00:54.020 2640-2716/com.ubiquity.sciencefacts D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
12-16 18:00:54.063 2640-2716/com.ubiquity.sciencefacts I/OpenGLRenderer: Initialized EGL, version 1.4
12-16 18:00:54.091 2640-2716/com.ubiquity.sciencefacts E/EGL_emulation: tid 2716: eglSurfaceAttrib(1165): error 0x3009 (EGL_BAD_MATCH)
12-16 18:00:54.091 2640-2716/com.ubiquity.sciencefacts W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0x7f8b8ec90c40, error=EGL_BAD_MATCH
12-16 18:34:41.488 27869-27869/com.ubiquity.sciencefacts I/art: Late-enabling -Xcheck:jni
12-16 18:34:41.561 27869-27869/com.ubiquity.sciencefacts W/System: ClassLoader referenced unknown path: /data/app/com.ubiquity.sciencefacts-2/lib/arm
12-16 18:34:41.586 27869-27869/com.ubiquity.sciencefacts D/AndroidRuntime: Shutting down VM
12-16 18:34:41.589 27869-27869/com.ubiquity.sciencefacts E/AndroidRuntime: FATAL EXCEPTION: main
                                                                           Process: com.ubiquity.sciencefacts, PID: 27869
                                                                           java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.ubiquity.sciencefacts/com.ubiquity.sciencefacts.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.ubiquity.sciencefacts.MainActivity" on path: DexPathList[[zip file "/data/app/com.ubiquity.sciencefacts-2/base.apk"],nativeLibraryDirectories=[/data/app/com.ubiquity.sciencefacts-2/lib/arm, /vendor/lib, /system/lib]]
                                                                               at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2327)
                                                                               at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                                               at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                                               at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                               at android.os.Looper.loop(Looper.java:148)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                                            Caused by: java.lang.ClassNotFoundException: Didn't find class "com.ubiquity.sciencefacts.MainActivity" on path: DexPathList[[zip file "/data/app/com.ubiquity.sciencefacts-2/base.apk"],nativeLibraryDirectories=[/data/app/com.ubiquity.sciencefacts-2/lib/arm, /vendor/lib, /system/lib]]
                                                                               at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
                                                                               at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
                                                                               at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
                                                                               at android.app.Instrumentation.newActivity(Instrumentation.java:1067)
                                                                               at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2317)
                                                                               at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
                                                                               at android.app.ActivityThread.-wrap11(ActivityThread.java) 
                                                                               at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                               at android.os.Looper.loop(Looper.java:148) 
                                                                               at android.app.ActivityThread.main(ActivityThread.java:5417) 
                                                                               at java.lang.reflect.Method.invoke(Native Method) 
                                                                               at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
                                                                            Suppressed: java.lang.ClassNotFoundException: com.ubiquity.sciencefacts.MainActivity
                                                                               at java.lang.Class.classForName(Native Method)
                                                                               at java.lang.BootClassLoader.findClass(ClassLoader.java:781)
                                                                               at java.lang.BootClassLoader.loadClass(ClassLoader.java:841)
                                                                               at java.lang.ClassLoader.loadClass(ClassLoader.java:504)
                                                                                    ... 12 more
                                                                            Caused by: java.lang.NoClassDefFoundError: Class not found using the boot class loader; no stack trace available
12-16 18:34:43.772 27869-27869/com.ubiquity.sciencefacts I/Process: Sending signal. PID: 27869 SIG: 9

IMPORTANT UPDATE: I built the program as an apk and installed it on my phone using that and it worked without issue. Does this imply a target error as was said below in the comments? Would this affect the distribution of my app (for future reference I am not actually distributing this)?

Answer 1

Bonus might be of help to someone:

1. First build a debuggable build by changing the following:

   Debuggable true and minifyEnabled false

2. Add logs to code bases where you expect the application crashes

3. Create an apk, and connect your device to you system and enable usb debugging on your mobile

4. open logcat in android studio and select the debuggable process from the dropdown

5. check the logs, it might give you hints on what is the issue.

Besides there can be a case, specifically for the android version 31:

There is this wonderful answer Answer you can try.

Besides try deleting .gradle folder inside the android folder in react native

And also do ensure you are using JDK 11, sometimes it crashes because of this too

Answer 2

For other possible reason if none above are working.

My app ran in the emulator with no problem but would not run on a Pixel device. I had the following line in the manifest under application:

android:testOnly="true"

Once this line was removed, the app worked perfectly on the device.

Answer 3

When you are debugging/ running your app using USB cable connected to Android Studio, for some devices, when you uninstall the app and try to run it again through studio it shows target error.

For this once you uninstall the app, simply disconnect your device from USB cable and connect again.

Answer 4

Try to enable USB Debugging Mode. Here's a manual

Answer 5

In most of the cases, just cleaning and rebuilding the project would do the trick.

Answer 6

You could also check your Build.Gradle file(s). In your case it should look like this:

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.1"

    defaultConfig {
        minSdkVersion 16
        targetSdkVersion 23
    }

    buildTypes {
        debug {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

be sure you disabled proguard by setting minifyEnabled to false. this can cause to be sure that this causes no additional errors ;)

Answer 7

Use multidexEnabled in your build.gradle:

defaultConfig {
     multiDexEnabled true
}

clean , build and run

Answer 8

Regarding your error, it seems there are missing some SDKs.

Check up your SDK manager if all the needed SDKs and SDK-tools are installed.