问题
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)?
回答1:
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.
回答2:
Use multidexEnabled in your build.gradle:
defaultConfig {
multiDexEnabled true
}
clean , build and run
回答3:
In most of the cases, just cleaning and rebuilding the project would do the trick.
回答4:
Try to enable USB Debugging Mode. Here's a manual
回答5:
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.
回答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 ;)
来源：https://stackoverflow.com/questions/41179790/android-studio-app-works-in-emulator-but-not-on-a-real-device