I'm going through the Java EE 6 Tutorials and on page 68 under SDK Installation Tips, it says:
"After you install the GlassFish Server, add the following directories to your PATH to avoid having to specify the full path when you use commands:
as-install-parent/bin
as-install/bin
How do you add these to the "PATH"? Is it the System Properties, Advanced tab, Environment Variables box that I need to edit inside? What if I already have other directories indicated in PATH already? Will the SDK get confused or does it not matter?
Is it the System Properties, Advanced tab, Environment Variables box that I need to edit inside?
That's one way, in Windows. In this case, if you have an open CMD window, you need to open a new one so that it will get the new settings.
What if I already have other directories indicated in PATH already?
The PATH variable is a list of directories separated by a semicolon. Simply add the semicolon and the new directory. Example:
C:\Program Files\Mercurial;C:\cygwin\bin
In an open CMD window, you can also use set:
set PATH=%PATH%;C:\glassfish\as-install-parent\bin;C:\glassfish\as-install\bin
In Unix, use export, and colons instead of semicolons.
export PATH=$PATH:/usr/glassfish/as-install-parent/bin:/usr/glassfish/as-install/bin
Of course, remember to replace C:\glassfish from my examples with the actual directory where you installed Glassfish.
One last thing, keep in mind this variable is only used by the operating system to find the executables in the bin folders; it's not used by Java nor Glassfish.
Related
Why is there no need to add the path of the java installation to the PATH variable when starting a jar with double-click while it is needed to start the jar from command line? Why does the OS only know where java is installed when executing with a double-click (without the PATH variable)?
Related Questions:
Is it necessary to set the path variable in java installation?
Is JAVA_HOME variable needed when Java Path is defined in system environment variable?
When on the command line, you call an executable and pass it a file as an argument. Since it does not know where this executable is, you either need to call it with an absolute path (Includes the entire path from the drive letter to the executable) or the executable must be present in one of the locations listed in the system PATH environment variable.
However, when double clicking a file Windows does not have the luxury of being told which application it should use ahead of time. To solve this issue, Windows keeps a global registry of programs, file extensions, and various metadata about them. This includes stuff like which icon to display for that file type, the path to the executable used to open that file, extensions associated with a given program, the path to the uninstaller to use if deleted from the control panel, and much more.
The Java installer handles updating the registry for you behind the scenes so you don't need to, however depending on your installation setting it may not update the system path since most people will only use the double clicking method.
I know this is SUPER basic. I am very new to all of this. I tried to download java and run a helloworld by following these instructions: https://docs.oracle.com/javase/tutorial/getStarted/cupojava/win32.html
I got an error when I tried to use the "javac" command to compile. This is what appears in the command prompt:
C:\Users\USer18\Desktop>javac HelloWorldApp.java
'javac' is not recognized as an internal or external command, operable program or batch file.
Does this mean I downloaded java incorrectly? When I downloaded it, there were 3 different things to choose from, but I could only choose one, so I chose the first one. I tried to download java again and select the second one, but it said it didn't work.
Thanks in advance for helping me!
From the tutorial you linked, it tells you to "consult the installation instructions" found here: https://docs.oracle.com/javase/8/docs/technotes/guides/install/install_overview.html
For Windows JDK, the instructions linked are here: https://docs.oracle.com/javase/8/docs/technotes/guides/install/windows_jdk_install.html#CHDEBCCJ
The part you need to look for is "Updating the PATH Environment Variable"
Updating the PATH Environment Variable
If you do not set the PATH variable, you need to specify the full path
to the executable file every time you run it, such as:
C:> "C:\Program Files\Java\jdk1.8.0\bin\javac" MyClass.java
It is useful to set the PATH variable permanently so it will persist
after rebooting.
To set the PATH variable permanently, add the full path of the
jdk1.8.0\bin directory to the PATH variable. Typically, this full path
looks something like C:\Program Files\Java\jdk1.8.0\bin. Set the PATH
variable as follows on Microsoft Windows:
Click Start, then Control Panel, then System.
Click Advanced, then Environment Variables.
Add the location of the bin folder of the JDK installation to the PATH variable in System Variables. The following is a typical value
for the PATH variable:
C:\WINDOWS\system32;C:\WINDOWS;C:\Program Files\Java\jdk1.8.0\bin
Note:
The PATH environment variable is a series of directories separated by semicolons (;) and is not case-sensitive. Microsoft Windows looks
for programs in the PATH directories in order, from left to right.
You should only have one bin directory for a JDK in the path at a time. Those following the first instance are ignored.
If you are not sure where to add the JDK path, append it.
The new path takes effect in each new command window you open after setting the PATH variable.
When ever we execute any command, it is searched in the directory where we are current in or mentioned in PATH environment variable. The oly thing which you need is just add <path of yourjdk>\bin to PATH
Windows 10 and Windows 8
In Search, search for and then select: System (Control Panel)
Click the Advanced system settings link.
Click Environment Variables. In the section System Variables, find the PATH environment variable and select it. Click Edit. If the PATH environment variable does not exist, click New.
In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.
In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.
Windows 7
From the desktop, right click the Computer icon.
Choose Properties from the context menu.
Click the Advanced system settings link.
Click the Advanced system settings link.
In the Edit System Variable (or New System Variable) window, specify the value of the PATH environment variable. Click OK. Close all remaining windows by clicking OK.
Reopen Command prompt window, and run your java code.
So I am trying to start with Java (as in, trying to get the dang thing to accept code). I download all the needed things (the SDK) from Java and such, but when it gets to the point where I have to do "javac" in Command Prompt to compile the notepad file, I just get the message saying that there is no command called "javac".
Anybody wanna share some insight?
To set the environment variable PATH: http://www.java.com/en/download/help/path.xml.
Also I recommend using an IDE such as netbeans or eclipse. They make it much easier when starting off in java, plus when getting into advanced projects with many classes, they help greatly.
You need to set the path to your java compiler for it to be found when you use the command prompt. This page explains how.
I would suggest setting the following environment variable:,
JAVA_HOME to point to the root of your java installation e.g. C:\Program Files\Java
than append the following to your PATH environment variable:
;%JAVA_HOME%\bin
than you will be able to use java and javac from the command line.
Also see this article from Microsoft on setting environment variables if your not familiar with it.
You need to add the Java bin directory (where javac.exe is located, assuming you're on Windows), to your system PATH.
Right click on "My Computer", go to Environment Variables, and add the bin directory where Java is installed to your PATH variable.
You will need to have the java bin directory on your path. So, on windows, if installed at c:\java, and bin is c:\java\bin (normally you have version number, jre vs sdk, etc), you will need to add that to your PATH environment variable. set PATH=c:\java\bin;%PATH% -- you could do this in a setlocal/endlocal block or set it permanatly for your machine.
Also, the JRE may not have javac -- you may need to dowload the SDK.
Starting with java by typing 'javac' at the command line satisfy my mother's definition of the phrase 'starting with' ... as in,
"Don't start with me, buddy."
You are likely to end up with a punch in the nose.
For your own sanity, pick one of Eclipse, or NetBeans, or IntelliJ, or the other popular IDEs, and start from there.
I have a very basic question to ask, that why do we need to add a semicolon at the end of PATH variable and why don't we add semicolon in JAVA_HOME variable?
I read lot of books and forums:
To separate different paths in PATH variable? or to tell the system or JRE not to look any further after that.
JAVA_HOME variable is to help the JRE to look for more files and extensions like JDBC drivers etc. in future development.
JAVA_HOME is used to specify a single directory. PATH specifies several directories, so you use a semi-colon to separate those directories.
JAVA_HOME is the location of the JDK or JRE installation. Many Java related libraries and files are stored here. It is a single location, not a set of locations and therefore there is no need to use a ';' to separate locations.
The PATH and CLASSPATH variables specify multiple locations, and therefore use ';' to delimit the entries.
Note that ';' is specific to Windows.
PATH is an operating system-specific idea. It just means, "when I type a command, check these paths as well". The current directory you are in is usually on the searched paths by default. If you think about it for a minute, you can easily imagine how much of a pain it would be to use a command line if you didn't have the idea of PATH.
So, given a PATH (with multiple directories), you need a way to separate the entries. Each operating system can use whatever character, but the two most popular are semi-colon (on Windows) and colon (on most systems Unix, e.g. Mac OS X).
JAVA_HOME just points to wherever your preferred Java installation is located. One value, so no need for a character to separate entries.
As an aside, you'll also run into CLASSPATH, which is the paths of all of the libraries (JARs) and resources (e.g. property files) your Java app is loading. CLASSPATH uses the same format/characters as PATH.
As an exercise, try writing a little bit of code that loops over and prints out the values of System.getProperties() and System.getenv(). It's a great way to see all of the little configuration elements.
A semicolon is the delimiter; it separates multiple items in a path.
JAVA_HOME only points to one place (the JDK/JRE directory)
Your PATH (or CLASSPATH) can encompass many locations.
That being said, putting a semicolon at the end of a path doesn't do anything and is ignored.
(Note that this is a colon in *nix rather than a semicolon)
JAVA_HOME is the root directory of JDK/JRE. On my system, JDK_HOME is:
C:\program files\java\jdk1.6.0_24
Since the command line tools (java, javac, jar, etc) are located in the bin directory, you puth %JAVA_HOME%\bin on the PATH, and not %JAVA_HOME% itself...
I got a native library that needs to be added to java.library.path. With JVM argument -Djava.library.path=path... I can set the path as I want.
My problem is that my other library (pentaho reporting) searches fonts based on the default java.library.path (including system directories etc) and the manual setting overrides the default path..
So : how can I add a path entry to the default java.library.path instead of overriding it (which seems to be done with -Djava.library.path)? (I wouldn't want to add the default path by hand, which wouldn't be nice for the sake of deployment)
EDIT: Sorry for missing details; I'm working with Eclipse. (The deployment is done with JNLP and there I can use nativelib under resources)
Had forgotten this issue... I was actually asking with Eclipse, sorry for not stating that originally.
And the answer seems to be too simple (at least with 3.5; probably with older versions also):
Java run configuration's Arguments : VM arguments:
-Djava.library.path="${workspace_loc:project}\lib;${env_var:PATH}"
Must not forget the quotation marks, otherwise there are problems with spaces in PATH.
If you want to add a native library without interfering with java.library.path at development time in Eclipse (to avoid including absolute paths and having to add parameters to your launch configuration), you can supply the path to the native libraries location for each Jar in the Java Build Path dialog under Native library location. Note that the native library file name has to correspond to the Jar file name. See also this detailed description.
SWT puts the necessary native DLLs into a JAR. Search for "org.eclipse.swt.win32.win32.x86_3.4.1.v3449c.jar" for an example.
The DLLs must be in the root of the JAR, the JAR must be signed and the DLL must appear with checksum in the META-INF/MANIFEST.MF for the VM to pick them up.
In Windows, like this:
-Djava.library.path="C:/MyLibPath;%PATH%"
%PATH% is your old -Djava.library.path
Can you get round this by calling System.load() programmatically to load your native library? This method (unlike System.loadLibrary()) allows you to specify an absolute path.
In UNIX systems, you can append to the LD_LIBRARY_PATH environment variable. On Windows, the JVM automatically sets the system property, java.library.path, to PATH; so if the dll is on your PATH, then you're set.
https://bugs.eclipse.org/bugs/show_bug.cgi?id=102239 states that there is no substitution mechanics implemented in Eclipse's launcher, at least no up to release Juno.
Thus it is (almost) impossible to append or prepend another library folder to java.library.path when launching Eclipse without prior knowledge of the default setting.
I wrote almost, cause it should be possible to let Eclipse startup, dump the content of java.library.path and stop Eclipse in one command. The dump would the be parsed and then taken as the input for launching Eclipse, i.e.
#!/bin/bash
# get default value of java.library.path (somehow)
default_lib_path=$( start_dump_stop_eclipse_somehow )
# now launch Eclipse
eclipse --launcher.appendVmargs \
-vmargs \
-Djava.library.path="/my/native/lib/folder:${default_lib_path}"
On Windows: Add the path to the library to the PATH environment variable.
On Linux: Add the path to the library to the LD_LIBRARY_PATH environment variable.
On Mac: Add the path to the library to the DYLD_LIBRARY_PATH environment variable.
java.library.path is initilized with the values of the variables above on its corresponding platform.
This should work on any IDE.
You can test if the value is what you expect by calling java -XshowSettings:properties
The solution offered by Rob Elsner in one of the comments above works perfectly (OSX 10.9, Eclipse Kepler). One has to append their additional paths to that separated by ":".
You could also use ${system_property:java.library.path} – Rob Elsner Nov 22 '10 at 23:01
Window->Preferences->Java->Installed JREs.
Choose your current
JRE(JDK) and click Edit.
Fill Default VM Arguments:
-Djava.library.path=/usr/local/xuggler/lib.
The native library file name has to correspond to the Jar file name. This is very very important.
Please make sure that jar name and dll name are same.
Also,please see the post from Fabian Steeg
My download for jawin was containing different names for dll and jar.
It was jawin.jar and jawind.dll, note extra 'd' in dll file name.
I simply renamed it to jawin.dll and set it as a native library in eclipse as mentioned in post
"http://www.eclipsezone.com/eclipse/forums/t49342.html"
For some reason I couldn't get multiple folders to work (well it did for a while but as soon as I needed more dlls and added more folders, none with white spaces in the path). I then copied all needed dlls to one folder and had that as my java.library.path and it worked. I don't have an explanation - if anyone does, it would be great.
Many of the existing answers assume you want to set this for a particular project, but I needed to set it for Eclipse itself in order to support integrated authentication for the SQL Server JDBC driver.
To do this, I followed these instructions for launching Eclipse from the Java commandline instead of its normal launcher. Then I just modified that script to add my -Djava.library.path argument to the Java commandline.
On Windows, I have found that the important thing is to start Eclipse from the command line rather than from the Start Menu or a shortcut, provided that the native DLL is in a directory in your PATH. Apparently, this ensures that the proper directory is on the path.