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Include multiple source directories in Qt for Android

I want to include Java source code from multiple directories (which are shared between projects) in a Qt for Android project. On http://imaginativethinking.ca/what-the-heck-how-do-i-share-java-code-between-qt-android-projects/ an approach is described which copies the Java source files:
# This line makes sure my custom manifest file and project specific java code is copied to the android-build folder
ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android
# This is a custom variable which holds the path to my common Java code
# I use the $$system_path() qMake function to make sure that my directory separators are correct for the platform I'm compiling on as you need to use the correct separator in the Make file (i.e. \ for Windows and / for Linux)
commonAndroidFilesPath = $$system_path( $$PWD/../CommonLib/android-sources/src )
# This is a custom variable which holds the path to the src folder in the output directory. That is where they need to go for the ANT script to compile them.
androidBuildOutputDir = $$system_path( $$OUT_PWD/../android-build/src )
# Here is the magic, this is the actual copy command I want to run.
# Make has a platform agnostic copy command macro you can use which substitutes the correct copy command for the platform you are on: $(COPY_DIR)
copyCommonJavaFiles.commands = $(COPY_DIR) $${commonAndroidFilesPath} $${androidBuildOutputDir}
# I tack it on to the 'first' target which exists by default just because I know this will happen before the ANT script gets run.
first.depends = $(first) copyCommonJavaFiles
export(first.depends)
export(copyCommonJavaFiles.commands)
QMAKE_EXTRA_TARGETS += first copyCommonJavaFiles
With later Qt versions the code has to be changed to this:
commonAndroidFilesPath = $$system_path($$PWD/android/src)
androidBuildOutputDir = $$system_path($$OUT_PWD/../android-build)
createCommonJavaFilesDir.commands = $(MKDIR) $${androidBuildOutputDir}
copyCommonJavaFiles.commands = $(COPY_DIR) $${commonAndroidFilesPath} $${androidBuildOutputDir}
first.depends = $(first) createCommonJavaFilesDir copyCommonJavaFiles
export(first.depends)
export(createCommonJavaFilesDir.commands)
export(copyCommonJavaFiles.commands)
QMAKE_EXTRA_TARGETS += first createCommonJavaFilesDir copyCommonJavaFiles
Is this the standard way to go, or is there some built-in functionality for including multiple Java source directories in Qt for Android projects?
Regards,

A much cleaner solution is this one:
CONFIG += file_copies
COPIES += commonJavaFilesCopy
commonJavaFilesCopy.files = $$files($$system_path($$PWD/android/src))
commonJavaFilesCopy.path = $$OUT_PWD/android-build

Why does Files.isHidden(Path) return false for directories on Windows?

From the documentation of Files.isHidden(Path) (emphasis mine):
Tells whether or not a file is considered hidden. The exact definition of hidden is platform or provider dependent. On UNIX for example a file is considered to be hidden if its name begins with a period character ('.'). On Windows a file is considered hidden if it isn't a directory and the DOS hidden attribute is set.
Depending on the implementation this method may require to access the file system to determine if the file is considered hidden.
From this I can understand what the expected behavior is. However, why is this the expected behavior?
The reason I'm wondering is because of the difference in behavior between Files.isHidden, DosFileAttributes.isHidden, and Windows' File Explorer. For instance, I can go into File Explorer and set a directory to be hidden and it will no longer show up (unless I configure it to show hidden items). If I test if said directory is hidden with Java then Files.isHidden returns false and DosFileAttributes.isHidden returns true. You can test this with the following code:
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.attribute.DosFileAttributes;
public class Main {
public static void main(String[] args) throws Exception {
final var directory = Path.of(args[0]).toAbsolutePath().normalize();
final var store = Files.getFileStore(directory);
final var dosAttrs = Files.readAttributes(directory, DosFileAttributes.class);
System.out.println("Directory : " + directory);
System.out.println("FileStore : " + store.name() + " [" + store.type() + "]");
System.out.println("Hidden (Files): " + Files.isHidden(directory));
System.out.println("Hidden (Dos) : " + dosAttrs.isHidden());
}
}
Note: I'm using Windows 10 and OpenJDK 11.0.1. My file system is NTFS.
Running this with:
java Main.java C:\path\to\hidden\directory
I get:
Directory : C:\path\to\hidden\directory
FileStore : OS [NTFS]
Hidden (Files): false
Hidden (Dos) : true
Note: This behavior appears to be part of WindowsFileSystemProvider. The method Files.isHidden(Path) simply forwards the call to the argument's FileSystem's provider. The implementation is basically:
DosFileAttributes attrs = ...; // get attributes
return !attrs.isDirectory() && attrs.isHidden();
I found this (non)-issue (JDK-8170334) where a comment says:
I don't think we have a bug here because the hidden attribute is meaningless on directories.
Yet File Explorer, which is core software on Windows, behaves like the hidden attribute is not meaningless on directories. So again, why does the Java implementation on Windows take into account whether or not the Path points to a directory? Or is Java correct and File Explorer is doing non-standard things?
I'm inclined to think File Explorer is correct because both CMD (via dir) and PowerShell (via Get-ChildItem) won't list hidden directories either; not unless the appropriate options are specified.

I checked documentation for file attributes provided by Microsoft for Windows platform. It says that if attribute FILE_ATTRIBUTE_HIDDEN = 2 (0x2) is set
The file or directory is hidden. It is not included in an ordinary directory listing.
As I can see in the class sun.nio.fs.WindowsConstants there is the same value definition used by DosFileAttributes.isHidden() method - public static final int FILE_ATTRIBUTE_HIDDEN = 0x00000002; which for my understanding should be mapped one to one with the attribute available for Windows, so in general hidden flag for a directory should be working in the same way as for a regular file.
In relation to operating system/file system integration, this behaviour seems to be incorrect.

Cloning java application on Windows

I am trying to start a new process with Runtime.exec() from my javafx application.
The new process is my javafx application (but in a new process, the "parent" one will still be open).
So I run javaw via the exec method and tell it my classpath. And here is my problem: the classpath contains whitespaces, so I need to quote every path. But I retrieve the path at runtime via java.class.path (since it is the same application).
Do I need to process the string and quote everything or is there an easy way to get this to work?
Here is the code:
public static void startInNewProcess() {
try {
Runtime r = Runtime.getRuntime();
File javaPath = new File(System.getProperty("java.home"), "bin/javaw");
File classPath = new File(System.getProperty("java.class.path"));
System.out.println("java loc: " + javaPath.toString());
System.out.println("classpath: " + classPath);
Process p = r.exec(javaPath.toString() + " -classpath " + classPath.getPath());
} catch (Exception e) {
e.printStackTrace();
}
}
I get the following string as classpath:
classpath: C:\Users\kwilhelm\git\ResourcePlaner\bin;C:\Program Files (x86)\eclipse\plugins\org.eclipse.fx.ide.css.jfx8_2.0.0.201506111511.jar;C:\Users\kwilhelm\git\ResourcePlaner\lib\itextpdf-5.5.6-javadoc.jar;C:\Users\kwilhelm\git\ResourcePlaner\lib\itextpdf-5.5.6-sources.jar;C:\Users\kwilhelm\git\ResourcePlaner\lib\itextpdf-5.5.6.jar;C:\Users\kwilhelm\git\ResourcePlaner\lib\controlsfx-8.40.9.jar
But javaw gives the error that it can't find mainclass "Files", so it can't handle the whitespace in the path.
So is there a way to get the classpath with quotes?
Is there a better solution?
Any help is apreciated

And here is my problem: the classpath contains whitespaces, so I need to quote every path.
Actually, no you don't.
And in fact, if you do attempt to quote every path, it is likely to mess up bigtime, because exec doesn't understand shell quoting.
What you actually need to do is this:
Process p = r.exec(new String[] {javaPath.toString(),
"-classpath",
classPath.getPath()});
This tells exec exactly where the boundaries of the command arguments are, so that it doesn't need to try (and fail) to figure it out for itself.
In fact, that still isn't right. You also need to add:
any other JVM options that the cloned instance needs,
a class name, and
any arguments required after the classname.
The classname is mandatory. (You left it out, and that is why the java command was outputting its help message!)

SCons not picking up all class files when creating a jar

SCons neophyte here. I am using it(version 2.0) to create a jar as follows:
compiled_classes = env.Java \
(target = compiled_classes_dir,
source = source_tld,
JAVAVERSION='1.6',
JAVACLASSPATH=['source_tld/libs/' +
file.name
for file in
Glob('source_tld/' +
'libs/*.jar')])
new_jar = env.Jar(target = jar_name,
source = compiled_classes_dir)
I am seeing an issue wherein class files belonging to classes that have inner classes(which when compiled into class files have a $ in the name) are not being handled properly i.e. they do not get included in the generated JAR. Any suggestions to address this would be greatly appreciated. TIA.
PS: This suggestion to add JAVAVERSION didn't seem to help.

Since SCons is incorrectly calculating the output classes I would suggest this workaround.
compiled_classes = env.Java \
(target = compiled_classes_dir,
source = source_tld,
JAVAVERSION='1.6',
JAVACLASSPATH=['source_tld/libs/' +
file.name
for file in
Glob('source_tld/' +
'libs/*.jar')])
#workaround to make sure classes are cleaned
env.Clean(compiled_classes, env.Dir(compiled_classes_dir))
# its important to set the JARCHDIR or the Jar command will not be run
# from the correct location if you want an executable Jar add the manifest here
new_jar = env.Jar(target = jar_name,
source = [compiled_classes_dir], JARCHDIR='$SOURCE')

Running a Java program from Adobe AIR's native process

I've use Adobe native process to run java program from my air app. Here the code and it works fine. But i should write absolute path to java runtime for that:
/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/bin/java.
If user installed java runtime in diff folder, or have diff version then this code would not work. How i can detect where java were installed or maybe there is another right way to run java applications from air applications? If i run java library from terminal command line then i could just write "java -jar pdfbox-app-1.6.0.jar" etc. and it runs fine.
private function convertPdf2Txt():void{
var arg:Vector.<String> = new Vector.<String>;
arg.push("-jar");
arg.push(File.applicationDirectory.resolvePath("pdfbox-app-1.6.0.jar").nativePath);
arg.push("ExtractText");
arg.push("-force");
arg.push(File.applicationStorageDirectory.resolvePath("Data/1.pdf").nativePath);
arg.push(File.applicationStorageDirectory.resolvePath("Data/1.txt").nativePath);
var fjava:File = new File("/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/bin/java");
if (fjava.exists==false){
Alert.show("Can't find Java Runtime in default folder.","Idea Rover",mx.controls.Alert.OK, null,null,imgInfo);
return;
}
var npInfo:NativeProcessStartupInfo;
npInfo = new NativeProcessStartupInfo();
npInfo.executable = fjava;
npInfo.arguments = arg;
var nativeProcess:NativeProcess;
nativeProcess = new NativeProcess();
nativeProcess.addEventListener(NativeProcessExitEvent.EXIT,onNativeProcessExit);
nativeProcess.start(npInfo);
}

Absolute path is:
Mac OS: /usr/bin/java
Win OS: (default)
64bit : C:\Program Files\Java
32bit : C:\Program Files (x86)\Java

rather than popping up an Alert, you could open a file selection dialog, using File.browseForOpen(). then, the File you want is contained in the event passed by the Event.SELECT handler. this flow seems standard for applications i've used that need to access other applications, but aren't sure where to find their executables.
var npInfo:NativeProcessStartupInfo = new NativeProcessStartupInfo();
// setup npInfo, nativeProcess...
var fjava:File = new File("/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/bin/java");
if (!fjava.exists) {
fjava.addEventListener(Event.SELECT, onFileSelected);
fjava.browseForOpen("Where is Java located?");
}
private function onFileSelected (evt:Event) :void {
npInfo.executable = evt.target;
nativeProcess.start(npInfo);
fjava.removeEventListener(Event.SELECT, onFileSelected);
}
of course, you can use the same logic to find the file java needs to launch as well.

You may be able to determine where the Java binaries are by looking at the JAVA_HOME environment variable. I'd like to do the same thing as you're doing, so I'll post more after I do more research.