While compiling java files through cmd (ie through javac command) it is written as filename.java but to run the same program we write filename and don't add the extension. Why is extension removed in java command or extension added in javac command ? Any specific reason.
When compiling, you specify the name of one or more source files, thus the .java extension
When running you specify the class name of the main class, thus no extension.
The difference becomes even more apparent, when the class is in a package:
javac mypackage/MyClass.java
java mypackage.MyClass
Related
I want to compile uic to PySide6 but I don't find how to install pyside6-uic tool. Where can I install pyside6-uic? I downloaded PySide6 but command pyside6-uic doesn't work.
There is a reference here in the title:
https://doc.qt.io/qtforpython/tutorials/basictutorial/uifiles.html#using-ui-files-from-designer-or-qtcreator-with-quiloader-and-pyside6-uic
Step 1. If you installed PySide6
a. In a venv then go to your venv's folder.
b. Globally then go to your python installation folder.
Step 2. Go to Lib then site-packages then PySide6.
Step 3. Copy uic.exe ( or uic if the file extension are hidden) create a folder called bin and paste what you've copied inside it.
To compile ui files from:
QtDesigner: From the top menu select Form -> View Python Code... then click on the save icon (floppy disk) from the newly opened window.
Command Prompt: pyside6-uic.exe mainwindow.ui > ui_mainwindow.py
PowerShell: pyside6-uic.exe mainwindow.ui -o ui_mainwindow.py
If you using virtual environment, when you install pyside6 with pip in the virtual environment there is a folder named Scripts there is the pyside6-uic.exe tool.
if you have install pyside6 globally in your system and you use visual studio code you can use the extension PySide2-vsc then when you installed you can go to preferences > settings and search the PySide2-vsc extension settings then look for the "Command to compile a .ui file into python". Then you can use that feature with right-click on .ui files.
I could solve this issue to add this Path to my %PATH% Variable on windows.
C:\Users\<YOUR_USER_PATH_NAME>\AppData\Roaming\Python\Python311\Scripts
The pyside6-uic tool is supposed to be installed automatically when installing the Python package.
Check if uic is in PATH
When using loadUiType, the Qt documentation (here) states that :
The internal process relies on uic being in the PATH. The pyside6-uic
wrapper uses a shipped uic that is located in the
site-packages/PySide6/uic, so PATH needs to be updated to use that if
there is no uic in the system.
But even then, I got the following error :
Cannot run 'pyside6-uic': "execvp: No such file or directory" -
Exit status QProcess::NormalExit ( 255 )
Check if 'pyside6-uic' is in PATH
For me, pyside6-uic was not located in site-packages/PySide6/uic. When reinstalling the module with pip, I noticed this message :
WARNING: The scripts pyside6-assistant, pyside6-designer, pyside6-genpyi,
pyside6-linguist, pyside6-lrelease, pyside6-lupdate, pyside6-rcc and pyside6-uic are
installed in '/Users/<user>/Library/Python/3.8/bin' which is not on PATH.
Consider adding this directory to PATH or, if you prefer to suppress this warning,
use --no-warn-script-location.
So make sure to add the right directory to your $PATH variable.
Once it's done, you will be able to use the pyside6-uic command to generate a Python class from a UI file :
pyside6-uic mainwindow.ui > ui_mainwindow.py
Loading a .ui from code
You can also load a .ui file from your code using either:
loadUiType (doc page) :
This function generates and loads a .ui file at runtime, and it
returns a tuple containing the reference to the Python class, and the
base class.
or QUiLoader (doc page):
enables standalone applications to dynamically create user interfaces
at run-time using the information stored in UI files or specified in
plugin paths
from PySide6.QtUiTools import QUiLoader
ui_file = QFile("mainwindow.ui")
ui_file.open(QFile.ReadOnly)
loader = QUiLoader()
window = loader.load(ui_file)
window.show()
Generally speaking, use absolute paths to access your UI files. Relative paths are susceptible to errors.
I have a working version of my project in eclipse.
I exported the project as a runnable jar.
Extracted (after converting to .zip)and tried to compile a particular java file from the command prompt
(Doing it this way since I have a project requirement, where input parameter inside that particular file can be modified and recompiled/run by users who wont have Eclipse)
I have used some external libraries( for Eg:json-simple,gson etc).They arent getting recognized , during compilation.
But if I run the class file(from the Eclipse compiled version), it gets executed properly
a)Tried to compile from root folder(using package name)
javac packageName.javaFileName.java
b) and went inside the package and compiled directly.
javac javaFileName.java
The a)part didnt compile at all saying classNotFound. The b)part started compiling but threw an error where none of the external libraries got recognized.(Getting --> error: cannot find symbol for places wherever the code/import of the external lib is used)
a)Tried to compile from root folder(using package name) javac
packageName.javaFileName.java b) and went inside the package and
compiled directly. javac javaFileName.java
The a)part didnt compile at all saying classNotFound.
Yes. javac requires you to specify a filesystem path to the (first) source(s) to compile. You appear instead to have tacked .java onto the end of the desired fully-qualified class name. Probably you want to compile from the root of the unpacked jar, specifying a correct path:
javac [options] package/name/className.java
for class package.name.className. (You can also compile from a different working directory if you specify an appropriate option, as discussed below.)
The b)part
started compiling but threw an error where none of the external
libraries got recognized.(Getting --> error: cannot find symbol for
places wherever the code/import of the external lib is used)
If the class you're compiling depends on others that also need to be compiled then javac would likely make a similar complaint about them. Either compile from the root (as in (a)), or specify the path to the source root via the -sourcepath option. Either way, there's no reason to descend into the source tree to compile.
But the external libs are actually a separate, albeit related, question. You don't need to compile these, but you do need to tell javac to use them as sources of classes. You would do that via the -classpath option, which you can abbreviate to -cp. If those were packaged in the jar itself (i.e. a "fat jar") then that should be fairly easy, something along these lines:
javac -cp .:lib/dependency1.jar:lib/dependency2.jar package/name/className.java
The "lib" part may vary, and the separator definitely differs depending on OS (on Windows it is ;, whereas on Mac / Linux / Solaris is is :, as shown).
If the external libs were not packaged into the main jar then the procedure is the same, but you might have a bigger challenge finding the needed jars. Also, such a jar is probably not runnable if you move it to a different machine. Nevertheless, you should probably look in META_INF/MANIFEST.MF, as it should contain the needed information.
I am having an XSLT to convert my xml into html format. I didn't achive any Experience about Saxon before but I'll try again and again.
This is the problem I had :
C:>java -cp saxon9he.jar net.sf.saxon.Transform -t -s:samples\date\books,xml-csl:samples\styles\books,xsl -o:c:\temp.html
Error: Main class net.sf.saxon.Transform could not be found or loaded
I did everything step by step from the Saxon Website :
https://www.saxonica.com/html/documentation/about/gettingstarted/gettingstartedjava.html
and I saw MR.Michael Kay Videos a lot before but it isn't work any way.
Can perhaps any one help me please ?
The problems are with Java, not with Saxon, in case that helps you look in the right place for documentation.
The message "Main class net.sf.saxon.Transform could not be found or loaded" is Java telling you that it can't find Saxon.
The bit of the command that tells it where to look is this:
java -cp saxon9he.jar net.sf.saxon.Transform
Here "java" is telling the operating system to load the Java virtual machine (which has succeeded). The "-cp" option is telling Java what Jar files to search for the relevant classes, and the "net.sf.saxon.Transform" part is saying what the relevant class is.
The problem is probably that there is no file called saxon9he.jar in the current working directory. Unfortunately Java doesn't give you an explicit error message for this, it just ignores this part of the command. Probably the current working directory isn't what you think it is. If you do "ls" or "dir" immediately before the "java" command, it will tell you what files are in the current working directory, which should include the saxon9he.jar file. If the JAR file is in some other directory, you can supply an explicit path, e.g. -cp c:/mike/java/saxon9he.jar.
I launched Dart Editor yesterday but it didn't work giving the error:
("A Java Runtime(jre) or Java Development Kit(jdk) must be avaible in
order to run DartEditor. No Java virtual machine was found after
searching the following loacations:
C:\Users\name\Donwloads\darteditor-windows-x64\dart\jre\bin\javaw.exe
jawaw.exe in your current PATH ")
Do you think how i going to fix this error ?
Thanks
Checkout this link:
https://www.dartlang.org/tools/editor/troubleshoot.html
"Launching Dart Editor"
Your Java version should have the same bit width as your Dart Editor version. For example, if you're using a 64-bit Dart Editor, then you should use 64-bit Java. Otherwise, you might see a message like this when you try to launch Dart Editor:
Failed to load the JNI shared library "C:\Program Files(x86)\Java\jre6\\bin\client\jvm.dll
To determine which version of Java you are running, do one of the following:
1-Go to CMD type java -version.
2-Go to Start -> Programs and Features.
Specifying the Java runtime
If necessary, you can specify the Java runtime that Dart Editor uses. Go to your Dart installation directory and add the following two lines to DartEditor.ini immediately before the existing ‑vmargs line:
-vm
/full/path/to/java
Important: On Windows, use double backslashes (\) as the directory separator:
-vm
c:\\bin\\java_jdk1.7.0\\bin\\javaw.exe
For example, DartEditor.ini might have:
-vm
/usr/local/buildtools/java/jdk-64/bin/java
-vmargs
You just need to download the Java Development SDK and your Java version should have the same bit width as your Dart Editor version. For example, if you're using a 64-bit Dart Editor, then you should use 64-bit Java. Otherwise, you might see a message like this when you try to launch Dart Editor:
You can download it here:
http://www.oracle.com/technetwork/java/javase/downloads/index.html?ssSourceSiteId=otnjp
and specify the java/bin directory in the darteditor.ini file.you can specify the Java SDK that Dart Editor uses. Go to your Dart installation directory and add the following two lines to DartEditor.ini immediately before the existing ‑vmargs line:
-vm
/full/path/to/java
Important: On Windows, use double backslashes () as the directory separator:
-vm
c:\\bin\\java_jdk1.7.0\\bin\\javaw.exe
For example, DartEditor.ini might have:
-vm
/usr/local/buildtools/java/jdk-64/bin/java
-vmargs
If it still doesn't work then you can follow this:
https://www.dartlang.org/tools/editor/troubleshoot.html
I made jre folder in my dart program folder.
And loaded there latest JRE. (Java runtime environment)
It stays in every new darteditor installation.
Better / right way would maybe be using path clause...
I dont know how to.. / dont want to use it.
My choise might need to load new version of jre now and then.
Hope this helps you...
The files A.java and B.class(Bytecode version of B.java) are in the current directory.
A.java uses B.java in the following way:
class A {
B b;
}
From what I have read the JDK tools first look in the directories where the Java standard libraries are installed. If the class is not found in the standard libraries, the tool searches in the class path. When no class path is defined, the default value of the class path is assumed to be the current directory. Then why is the following command not working:
C:\current> javac A.java
The package structure must match the directory structure, otherwise javac will fail.
http://kevinboone.net/classpath.html
Comment out or get rid of the package statements in the begin of your classes. Since you do keep both java classes in the directory where you compile, the compiler should be able to find the B.class without trouble.