Develop Reference

UnsatisfiedLinkError: no opencv_java249 in java.library.path

Running into some problems making a piece of code run on my mac.
Had someone write me an image analysis java app but I keep getting this error when trying to run it on netbeans.
run: Exception in thread "main" java.lang.UnsatisfiedLinkError: no
opencv_java249 in java.library.path at
java.lang.ClassLoader.loadLibrary(ClassLoader.java:1857) at
java.lang.Runtime.loadLibrary0(Runtime.java:870) at
java.lang.System.loadLibrary(System.java:1119) at
image.prossing.Test.main(Test.java:28) Java Result: 1 BUILD SUCCESSFUL
(total time: 0 seconds)
Have the netbeans project, and added the necessary jar files as libraries. The programmer told me to download the correct OpenCV version and copy the opencv.dll file to my java/jre/bin folder. But I cannot find the dll file or the java/jre folder.
I know most programming happens on windows for a reason. Hope someone can help me resolve this issue and run this application on my mac.
Here is the first part of the code, the part that is most probably creating the error:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package image.prossing;
/**
*
* #author Dumith Salinda
*/
import java.util.ArrayList;
import java.util.List;
import org.opencv.core.Core;
import static org.opencv.core.Core.FONT_HERSHEY_SIMPLEX;
import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Point;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.highgui.Highgui;
import org.opencv.imgproc.Imgproc;
public class Test {
public static void main(String[] args) {
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Sorry if it's not that clear, let me know what info to add if something is missing or not clear.
Would truly appreciate any help you could give. Sincerely
Meir Warcel

Look into your OpenCV directory;
For an example this; (installed using brew install opencv3 --with-java --with-python3)
/usr/local/Cellar/opencv3/XXX/share/OpenCV/java
You will see;
libopencv_javaXXX.so opencv-XXX.jar
Now that you already have OpenCV's native library for Java (libopencv_javaXXX.so) compiled with you, the only thing left is, mac's dynamic library.
Link libopencv_javaXXX.so to libopencv_javaXXX.dylib;
ln -s libopencv_javaXXX.so libopencv_javaXXX.dylib
Now add /usr/local/Cellar/opencv3/XXX/share/OpenCV/java as Native Library Locations in IntelliJ or something similar in Eclipse.
Or add this to your JVM arguments;
-Djava.library.path=/usr/local/Cellar/opencv3/XXX/share/OpenCV/java

On a mac running OSX Yosemite, I dropped the libopencv_java2412.dylib file into /Library/Java/Extensions and it worked.
After you build opencv, the libopencv_java2412.dylib is generated in /build/lib.

After Spending a lots of time , and using different suggestions from StackOverflow I managed to get solution for windows. but I am adding a solution for mac as well. hope it should work.
Load your lib as per your system configuration.
private static void loadLibraries() {
try {
InputStream in = null;
File fileOut = null;
String osName = System.getProperty("os.name");
String opencvpath = System.getProperty("user.dir");
if(osName.startsWith("Windows")) {
int bitness = Integer.parseInt(System.getProperty("sun.arch.data.model"));
if(bitness == 32) {
opencvpath=opencvpath+"\\opencv\\x86\\";
}
else if (bitness == 64) {
opencvpath=opencvpath+"\\opencv\\x64\\";
} else {
opencvpath=opencvpath+"\\opencv\\x86\\";
}
}
else if(osName.equals("Mac OS X")){
opencvpath = opencvpath+"Your path to .dylib";
}
System.out.println(opencvpath);
System.load(opencvpath + Core.NATIVE_LIBRARY_NAME + ".dll");
} catch (Exception e) {
throw new RuntimeException("Failed to load opencv native library", e);
}
}
2.now use this method as per your need
public static void main(String[] args) {
loadLibraries();
}

Building on Harsh Vakharia's answer i tried installing OpenCV on my mac with macports:
sudo port install opencv +java
ls /opt/local/share/OpenCV/java
libopencv_java343.dylib opencv-343.jar
To use this library I was hoping to be able to modify the library path at runtime which was discussed in
Adding new paths for native libraries at runtime in Java
And ended up with the following helper class and unit test. The code is now part of the
Self Driving RC-Car open Source project in which I am a comitter.
JUnit Test
/**
* #see <a href=
* 'https://stackoverflow.com/questions/27088934/unsatisfiedlinkerror-no-opencv-java249-in-java-library-path/35112123#35112123'>OpenCV
* native libraries</a>
* #throws Exception
*/
#Test
public void testNativeLibrary() throws Exception {
if (debug)
System.out.println(String.format("trying to load native library %s",
Core.NATIVE_LIBRARY_NAME));
assertTrue(NativeLibrary.getNativeLibPath().isDirectory());
assertTrue(NativeLibrary.getNativeLib().isFile());
NativeLibrary.load();
}
NativeLibrary
package com.bitplan.opencv;
import java.io.File;
import java.lang.reflect.Field;
import java.util.Arrays;
import org.opencv.core.Core;
/**
* load OpenCV NativeLibrary properly
*/
public class NativeLibrary {
protected static File nativeLibPath = new File("../lib");
/**
* get the native library path
*
* #return the file for the native library
*/
public static File getNativeLibPath() {
return nativeLibPath;
}
/**
* set the native library path
*
* #param pNativeLibPath
* - the library path to use
*/
public static void setNativeLibPath(File pNativeLibPath) {
nativeLibPath = pNativeLibPath;
}
/**
* get the current library path
*
* #return the current library path
*/
public static String getCurrentLibraryPath() {
return System.getProperty("java.library.path");
}
/**
* Adds the specified path to the java library path
*
* #param pathToAdd
* the path to add
* #throws Exception
* #see <a href=
* 'https://stackoverflow.com/questions/15409223/adding-new-paths-for-native-libraries-at-runtime-in-java'>Stackoverflow
* question how to add path entry to native library search path at
* runtime</a>
*/
public static void addLibraryPath(String pathToAdd) throws Exception {
final Field usrPathsField = ClassLoader.class.getDeclaredField("usr_paths");
usrPathsField.setAccessible(true);
// get array of paths
final String[] paths = (String[]) usrPathsField.get(null);
// check if the path to add is already present
for (String path : paths) {
if (path.equals(pathToAdd)) {
return;
}
}
// add the new path
final String[] newPaths = Arrays.copyOf(paths, paths.length + 1);
newPaths[newPaths.length - 1] = pathToAdd;
usrPathsField.set(null, newPaths);
}
public static File getNativeLib() {
File nativeLib = new File(getNativeLibPath(),
"lib" + Core.NATIVE_LIBRARY_NAME + ".dylib");
return nativeLib;
}
/**
* load the native library by adding the proper library path
*
* #throws Exception
* - if reflection access fails (e.g. in Java9/10)
*/
public static void load() throws Exception {
addLibraryPath(getNativeLibPath().getAbsolutePath());
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
}
}

Exception is occurring from below line of code:
System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
Your program is trying to load a native library by the name of argument in call to loadLibrary method, which it is not able to locate. Make sure that native library (opencv.dll) is placed at one of the locations present in java.library.path system property as JVM looks at these locations for loading any native library (which might not contain 'java/jre/bin').
You can print java.library.path in your program like below:
System.out.println(System.getProperty("java.library.path"));

You cannot just put Windows library (dll file) on Mac and have it running - you need to compile the library for Mac first (or get Mac version of the library).
Please see here for tips on how to do it:
.dll Equivalent on Mac OS X
How do third-party libraries work in Objective-C and Xcode?
How to use a Windows DLL with Java in Mac OS X?

Instead of struggling with manual installation of OpenCV libraries I suggest you use OpenCV Java library packaged by OpenPnP (https://github.com/openpnp/opencv) that includes all required DLL.
It does not require additonal steps except of adding it to your build automation tool configuration (Gradle in my case) and adding the following code to load the library:
System.loadLibrary(org.opencv.core.Core.NATIVE_LIBRARY_NAME);

Just add into the path the folder where your opencv_java249.dll is; it would be something like C:\bin\opencv\build\java\x32 or C:\bin\opencv\build\java\x64 depending of your machine architecture. The problem is that java.library.path is actually the path variable.

netebans right klick project chosew properti
chose run, working direktory, click Browser change to opencv folder, release/lib,

Eclipse: saved LaunchConfiguration overrides LaunchType

Not sure if it will be Eclipse or Eclipse-plugin-dev answer.
In open-source Nodeclipse project plugin.xml defines that .coffee file can be launched as coffee, coffee --compile or Node with monitor (There are 3 defined LaunchShortcuts).
First time it work fine, but then consequent launches only repeat previous LaunchType. I have found that deleting saved LaunchConfiguration (from Run -> Run Configurations) will let it run again (and then only as this type again)
The code in question is LaunchShortcut (see snippet below), however there is no any if checking, so this behavior should be deeper in Eclipse org.eclipse.debug module.
How can saved LaunchConfiguration override LaunchType ?
/**
* Launch an file,using the file information, which means using default
* launch configurations.
*
* #param file
* #param mode
*/
private void launchFile(IFile file, String mode) throws CoreException {
// check for an existing launch config for the file
String path = file.getFullPath().toString();
ILaunchManager launchManager = DebugPlugin.getDefault().getLaunchManager();
ILaunchConfigurationType type = launchManager.getLaunchConfigurationType(Constants.LAUNCH_CONFIGURATION_TYPE_ID);
ILaunchConfiguration configuration = createLaunchConfiguration(type, path, file);
DebugUITools.launch(configuration, mode);
// then execution goes in LaunchConfigurationDelegate.java launch() method
}
/**
* Create a new configuration and set useful data.
*
* #param type
* #param path
* #param file
* #return
* #throws CoreException
*/
private ILaunchConfiguration createLaunchConfiguration(ILaunchConfigurationType type, String path, IFile file) throws CoreException {
String configname = file.getFullPath().toString().replace('/', '-');
if(configname.startsWith("-")) {
configname = configname.substring(1);
}
ILaunchConfiguration[] configs = DebugPlugin.getDefault().getLaunchManager().getLaunchConfigurations(type);
for(ILaunchConfiguration config : configs) {
if(configname.equals(config.getName())) {
return config;
}
}
// create a new configuration for the file
ILaunchConfigurationWorkingCopy workingCopy = type.newInstance(null, configname);
workingCopy.setAttribute(Constants.KEY_FILE_PATH, path);
setMoreAttributes(workingCopy);
return workingCopy.doSave();
}
protected void setMoreAttributes(ILaunchConfigurationWorkingCopy workingCopy) {
// stub for extension
}
Help! The code snippet is maybe not enough to answer the question, but references files and everything is in Github repository. The question was raised, because I am not sure if it is possible at all to have many Run Configuration for the same file. Then code snippets doesn't matter at all.
Update: Looking after a while at plugin.xml defines that .coffee file can be launched , I noticed that I am actually using the same <configurationType
id= "org.nodeclipse.debug.launch.LaunchConfigurationType" > in all 5 cases. However adding unique LaunchConfigurationType id for every launch makes no difference.

You can create the launch configuration with this:
Creating a Java application launch configuration
Launch groups can also be setle with this help:
Launch Group
Until here Im pretty sure you have knowledge about, so lets keep moving; You can have different launch configuration for the same file, thats handled with the launch group tool, what I dont get is if you want those different configuration for the same environment or not.
Also here Launch Configuration Types and here Adding launchers to the platform you cand find information about the struct of the launch type file
To finish here Interface ILaunchConfigurationTabGroup is the interface of the launch type tab group;
My Suggestion in codelines:
<extension point="org.eclipse.debug.ui.launchConfigurationTabGroups">
<launchConfigurationTabGroup
<"launchConfigurationType1"
<"/launchConfigurationType1">
<"launchConfigurationType2"
<"/launchConfigurationType2">
//and so on...
</launchConfigurationTabGroup>
</extension>

Dynamically adding mojo-generated code to source path

I have authored a mojo that generates code and sticks it under {root}/target/generated-sources/foo. When I execute:
mvn clean install
I get errors indicating that the generated sources are not being included in the build path (the generated files are there, but not being picked up in the compile phase). I understand from this answer that I need to dynamically add {root}/target/generated-sources/foo as a source directory for the POM. Problem is, I haven't been able to track down any information on how to do this.
As a backup plan, I intend to use the Build Helper Maven Plugin, but I was hoping to do this automatically in my mojo if possible.

I prefer to add this to my Mojo:
/**
* The current project representation.
* #parameter expression="${project}"
* #required
* #readonly
*/
private MavenProject project;
/**
* Directory wherein generated source will be put; main, test, site, ... will be added implictly.
* #parameter expression="${outputDir}" default-value="${project.build.directory}/src-generated"
* #required
*/
private File outputDir;
Obviously you can change the default-value to match your own pattern.
And then in the execute() method:
if (!settings.isInteractiveMode()) {
LOG.info("Adding " + outputDir.getAbsolutePath() + " to compile source root");
}
project.addCompileSourceRoot(outputDir.getAbsolutePath());

Is it possible to run maven plugin from java class?

Need to run maven jaxb2 plugin from my app, at run-time. Is it possible?

Maybe i have done something that could help you:
/**
* #author swoeste
*
*/
public class MavenExecutor {
private final File configuration;
private final ClassWorld classWorld;
/**
* Constructor for a new maven executor.
*
* #param aConfiguration
*/
public MavenExecutor( final File aConfiguration ) {
this.configuration = aConfiguration;
this.classWorld = new ClassWorld( "plexus.core", this.getClass().getClassLoader() ); //$NON-NLS-1$
}
/**
* This method is used to perform a mvn command on the given pom. The original
* command must be given, also the sub folder and the marker folder in the working directory. The working directory
* and the configuration file will be added before execution.
*
* #param cmd the mvn command to execute
* #param pom the absolute path to a maven pom file
* #param output the absolute path to the working directory
* #param folder the output sub folder of the working directory
* #param marker the marker sub folder of the working directory
* #return
*/
public int unpack( final String cmd, final File pom, final File output, final String folder, final String marker ) {
final List<String> commands = new ArrayList<String>( //
Arrays.asList( cmd.split( ConfigurationConstants.MAVEN_DELIMITER ) ) );
commands.add( "-DoutputDirectory=" + output.getAbsolutePath() + folder ); //$NON-NLS-1$
commands.add( "-DmarkersDirectory=" + output.getAbsolutePath() + marker ); //$NON-NLS-1$
commands.add( "-gs=\"" + this.configuration.getAbsolutePath() + "\"" ); //$NON-NLS-1$//$NON-NLS-2$
commands.add( "-f=\"" + pom.getAbsolutePath() + "\"" ); //$NON-NLS-1$ //$NON-NLS-2$
return MavenCli.doMain( commands.toArray( new String[commands.size()] ), this.classWorld );
}
}
I dont know what exactly you want to do, but if you want to execute a maven plugin on a maven project the above code will work. In my case i execute a mvn dependency:unpack-dependencies command on a project.
To get the above working you need this dependency:
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-embedder</artifactId>
<version>3.0.3</version>
</dependency>
PS: A good resource for information about how to execute maven things from java is the implementation of the m2eclipse plugin ;)

I you really need that, of course you can. Just download sources of the plugin and look inside what's going on there. You can instantiate a proper Mojo (class that implements plugin's goal) and execute it. However, usually plugins' goals depend heavily on Maven project context that might be really hard to provide (or even mock somehow) so Mojo was able to execute without errors.
I don't know your specific situation, but I'm 99% sure that it would be really more sensible to write own implementation of something you want to achieve, potentially based on stuff you found in the plugin's source code (to not write everything on your own).

simple checkout from svn via javahl

I want to use javahl to checkout sources from svn from within a java program.
Trying Javahl because it seems to be free, also for commercial use.
I need to checkout something like http://example.com/svn/project1/trunk to a local directory.
That should be a rather straight-forward process, just a few lines of code? Still i couldnt find any tutorials on how to do that.
Could you give some example java lines?

I know the question is old, but I had to do something similar today. I also couldn't find any good tutorials and ended up using the unit tests as my reference.
Here's some Java code that worked for me:
import org.apache.subversion.javahl.ClientException;
import org.apache.subversion.javahl.SVNClient;
import org.apache.subversion.javahl.types.Depth;
import org.apache.subversion.javahl.types.Revision;
...
static void checkout(String reproUrl, String workingDirectory) throws ClientException {
SVNClient client = new SVNClient();
client.checkout(
reproUrl,
workingDirectory,
Revision.HEAD,
Revision.HEAD,
Depth.infinity,
false,
false);
}
And if you need to authenticate, SVNClient has username(String) and password(String) methods.

look
http://wiki.svnkit.com/Getting_Started_With_SVNKit
and
http://wiki.svnkit.com/Managing_A_Working_Copy
private static long checkout( SVNURL url , SVNRevision revision , File destPath , boolean isRecursive ) throws SVNException {
SVNUpdateClient updateClient = ourClientManager.getUpdateClient( );
/*
* sets externals not to be ignored during the checkout
*/
updateClient.setIgnoreExternals( false );
/*
* returns the number of the revision at which the working copy is
*/
return updateClient.doCheckout( url , destPath , revision , revision , isRecursive );
}