Develop Reference

Input stream must not be null exception in gradle project

I have MainClass
public class MainClass extends Application {
#Override
public void start(Stage primaryStage) {
try{
Image img = new Image(getClass().getResourceAsStream(".\\build\\resources\\main\\img\\h1.jpg"));
System.out.println("ok");
}
catch(Exception ex){
System.out.println(ex.getMessage());
}
}
public static void main(String[] args) {
launch(args);
}
}
and my image is in \build\resources\main\img\h1.jpg directory
my project files:
When I run project it gives Input stream must not be null exception.

Resource paths are not separated by \ Furthermore they start at the resource root. In this case the path "/img/h1.jpg" should do the trick assuming your IDE properly includes the resources in the classpath at runtime.
getResource(AsStream) does not access the data via file path; The data may not be available as file at all, but as entry in a JAR file. If you need to refer to a file that is not included in the classpath, use File's functionality to convert to a URI or use a FileInputStream:
new Image(new File(".\\build\\resources\\main\\img\\h1.jpg").toURI().toString())

Calling static jar function from Unity3D

I made and compiled a Android Library, containing a simple class and a simple static function:
package moo;
public class MyTestClass {
public static String Foo(){
return "Foo from Moo";
}
}
I placed the .jar in my Assets/Plugins/Android Folder. Then In Unity:
void OnGUI () {
string somestring = "foooooooooooOOooo";
AndroidJavaClass testClass = new AndroidJavaClass("moo.MyTestClass");
somestring = testClass.CallStatic<string>("Foo");
GUI.Label (new Rect (20, 20, 100, 20), somestring);
}
And I get an error:
JNI: Unable to find method id for 'Foo' (static)
UnityEngine.AndroidJavaObject:CallStatic(String, Object[])
Am I missing something to call my static method?
Thanks!

there are 2 problem as far as I can see:
you have to put your jar package to Assets/Plugins/Android/bin;
you will always get this error on your windows/mac editor, you have to run this on your android device;

The name 'Assets' does not exist in the current context

I have a problem with this line of code. Want to create sqlite database on the device.
string dbPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal) + "\\test.db";
if (!System.IO.File.Exists(dbPath))
using (System.IO.Stream sr = ***Assets***.Open("test.db"))
{
using (System.IO.Stream srTo = System.IO.File.Create(dbPath))
{
sr.CopyTo(srTo);
}
}
This message gives the:
The name 'Assets' does not exist in the current context
have a similar project, but more comprehensive than big. There is no error. They Assets Where I'm following definition defines a cs file in c drive gives reference to Android.Content.ContextWrapper.
is not on The project the path.
[How the file was added application?

If you aren't doing this in an activity you need a reference to the Activity/Context. You will need to pass this in to your helper class in the constructor.
public yourClass(Activity context.......){
context.Assets.Open("your.db");
}

You can do like this:
using (System.IO.Stream sr = Android.App.Application.Context.Assets.Open("test.db"))
{
using (System.IO.Stream srTo = System.IO.File.Create(dbPath))
{
sr.CopyTo(srTo);
}
}

Android, generate jni Header Files with javah , show error that can't find org.opencv.core.Mat

I just have an annoying problem with jni when i compile the native method in java class with javah to generate JNI header files.
If the class has used 3rd-party package, For example: org.opencv.core.Mat, then the javah will show the error that can't find the org.opencv.core.Mat class.
The OpenCV sample code as below:
package org.opencv.samples.fd;
import org.opencv.core.Mat;
import org.opencv.core.MatOfRect;
public class DetectionBasedTracker
{
public DetectionBasedTracker(String cascadeName, int minFaceSize) {
mNativeObj = nativeCreateObject(cascadeName, minFaceSize);
}
public void start() {
nativeStart(mNativeObj);
}
public void stop() {
nativeStop(mNativeObj);
}
public void setMinFaceSize(int size) {
nativeSetFaceSize(mNativeObj, size);
}
public void detect(Mat imageGray, MatOfRect faces) {
nativeDetect(mNativeObj, imageGray.getNativeObjAddr(), faces.getNativeObjAddr());
}
public void release() {
nativeDestroyObject(mNativeObj);
mNativeObj = 0;
}
private long mNativeObj = 0;
private static native long nativeCreateObject(String cascadeName, int minFaceSize);
private static native void nativeDestroyObject(long thiz);
private static native void nativeStart(long thiz);
private static native void nativeStop(long thiz);
private static native void nativeSetFaceSize(long thiz, int size);
private static native void nativeDetect(long thiz, long inputImage, long faces);
}
First, I used the command
javah -classpath bin/classes -bootclasspath (the directory of android.jar) -d jni (packageName + ClassName) , shows the error "can't find the org.opencv.core.Mat
Then I modified the command to
javah - classpath bin/classes - bootclasspath (the dir of android.jar) ; (the dir of the opencv lib jar) -d jni ..." ", this time it shows error
Exception
Exception in thread "main" java.lang.IllegalArgumentException: Not a valid class
name: E:\Computer_Language\Java\soft_android\OpenCV-2.4.3-rc-android-sdk\OpenCV
-2.4.3-rc-android-sdk\sdk\java\bin\opencv library - 2.4.3.jar
at com.sun.tools.javac.api.JavacTool.getTask(JavacTool.java:177)
at com.sun.tools.javac.api.JavacTool.getTask(JavacTool.java:68)
at com.sun.tools.javah.JavahTask.run(JavahTask.java:509)
at com.sun.tools.javah.JavahTask.run(JavahTask.java:335)
at com.sun.tools.javah.Main.main(Main.java:46)
I think, adding the directory of opencv lib in -bootclasspath is useful and neccessary. The error is because i just added two path in -bootclasspath or the format is something wrong?
Really confused.
Please give some help , thank u!

This is what I did:
1.Open Command line, type to the (project)/bin/classes:
2.type: javah -classpath (opencv4android sdk path)/java/bin/classes:(your project location)/bin/classes -jni (your java class file that contains the native library interfaces)
In my project. I did:
javah -classpath /home/zijun/Dev/adt/OpencvAndroid/sdk/java/bin/classes:/home/zijun/workspace/LocTM/bin/classes -jni com.brainport.loctm.TMatching
That works on Linux Ubuntu 12.04.02 64bit OS

I encountered the same problem too,it cost me half day.I just copy DetectionBasedTracker.java to my poject.I use Android Studio.When I use ExternalTools>javah to generate .h files,the console print cant find org.opencv.core.Mat.copying mat.java & matofRect.java to the directory DetectionBasedTracker.java exists just cause more java class cant be find.finally,I find this problem was caused by the import * clause in java file.and we seldom use java class in native method we defined.so I cut these java method and got this:
package cn.ntu.tonguefur.nativemethod;
public class DetectionBasedTracker{
private static native long nativeCreateObject(String cascadeName,int minFaceSize);
//Other native methods
private static native void nativeDetect(long thiz,long inputImage,long faces);
}
Now you can freely use javah command to generate .h
file.After that,add java methods and import packages you need.

Jersey on Jetty on Android throws ContainerException: The ResourceConfig instance does not contain any root resource classes

I'm trying to run Jersey on Jetty on Android.
I've created an Android that instantiate a Jetty Server with a Jersey Servlet. Anyway when I start Jetty and visit a REST resource (in my case: http://192.168.1.12:8080/api/hello) I get a ContainerException with message: The ResourceConfig instance does not contain any root resource classes. (see exception stack trace below).
Any idea why?
MORE DETAILS:
Logcat is giving the following SEVER WARNINGS.
The following errors and warnings have been detected with resource and/or provider classes:
SEVERE: Missing dependency for field: private java.lang.ThreadLocal com.sun.jersey.server.impl.container.servlet.JSPTemplateProcessor.requestInvoker
SEVERE: Missing dependency for field: private java.lang.ThreadLocal com.sun.jersey.server.impl.container.servlet.JSPTemplateProcessor.requestInvoker
This is strange cause java.lang.ThreadLocal is available for Android and HttpServletRequest and HttpServletResponse should be available since I've included servlet-api-2.5.jar in the libs folder.
Jersey is dependent on some javax libraries (jaxb-api-2.2.2.jar,jndi-1.2.1.jar,stax-api-1.0-2.jar) which I had to add to project and set the --core-library parameter temporary to ignore dex warning about javax packages as dependencies.
I also removed the following classes (RenderedImageProvider,DataSourceProvider,MimeMultipartProvider from package com.sun.jersey.core.impl.provider.entity from jersey core jar) to avoid dependencies on java.awt and javax.mail.
EXCEPTION trace:
javax.servlet.UnavailableException: com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes.
at org.eclipse.jetty.servlet.ServletHolder.makeUnavailable(ServletHolder.java:409)
at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:450)
at org.eclipse.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:331)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:476)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:517)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:935)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:404)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:184)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:870)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
at org.eclipse.jetty.server.Server.handle(Server.java:346)
at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.java:596)
at org.eclipse.jetty.server.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:1051)
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:592)
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:214)
at org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:426)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:520)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:40)
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:528)
at java.lang.Thread.run(Thread.java:1019)
Start Server Android Activity:
public class StartServerActivity extends Activity {
private Server webServer;
private final static String LOG_TAG = "Jetty";
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
System.setProperty("java.net.preferIPv4Stack", "true");
System.setProperty("java.net.preferIPv6Addresses", "false");
webServer = new Server(8080);
ServletHolder servletHolder = new ServletHolder(com.sun.jersey.spi.container.servlet.ServletContainer.class);
servletHolder.setInitParameter("com.sun.jersey.config.property.packages", "com.famenu.server.resources");
ServletContextHandler servletContextHandler = new ServletContextHandler(webServer, "/api", true, false);
servletContextHandler.addServlet(servletHolder, "/hello");
webServer.setHandler(servletContextHandler);
try {
webServer.start();
Log.d(LOG_TAG, "started Web server");
}
catch (Exception e) {
Log.d(LOG_TAG, "unexpected exception starting Web server: " + e);
}
}
}
Jersey Resource:
package com.famenu.server.resources;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
#Path("/")
public class HelloResource {
#GET
#Produces("text/plain")
public String getMsg() {
return "Hello Resource";
}
}
I'm using Jetty 7.3.0.v20110203 , Jersey 1.12 , Android 1.6
I arrived till this point after another exception explained here

don't use package/any other scanning on .. not supported platforms.
Classnames property: com.sun.jersey.config.property.classnames should work for you (you need to explicitly declare all your root resource (#Path annotated) classes).