Develop Reference

Run a jar file only with jre [duplicate]

When trying to check the current version of Java in which I am running, I received the error "java is not recognized as an internal or external command, operable program or batch file.".
I am running Windows 7 OS and have downloaded the latest JDK and felt I may have accidentally deleted the java from machine as before I was able to check the Java version using the command "java -version".
What software must I download to get Java working on my machine again?
EDIT:
I have managed to get Java running from my cmd again after ensuring all environment variables pointed to the current Java SDK.

You need to configure your environment variables, JAVA_HOME and PATH.
JAVA_HOME must contain the path to java, and you should add %JAVA_HOME%\bin to PATH
Alternatively, you can simply add to your PATH the whole path to the bin folder, without the JAVA_HOME variable, however, this makes a little more annoying when you need to have more than one java version on your machine (that way you only need to change JAVA_HOME and don't even bother with PATH)

For Windows 7:
Right click on My Computer
Select Properties
Select Advanced System Settings
Select the Advanced tab
Select Environment Variables
Select Path under System Variables
Click on the Edit button
In Variable value editor paste this at the start of the line
C:\Program Files\Java\jdk1.7.0_72\bin;
Click Ok then Ok again
Restart command prompt otherwise it won't see the change to the path variable
Type java -version in the command prompt.
Notes on Step 8:
The version of java in this may be different from the one used here -- this is only an example.
There will probably be other values in the path variable. It is really important that you don't delete what's already there. That's why the instructions say to paste the given value at the start of the line -- this means that you don't remove the existing value, you just put java before it. This also fixes any problems you'd be getting if an other version of java is also on the path.
Notes on Step 6:
This sets the path for the computer, not for the individual user. It may be that you're working on a computer which other developers also use, in which case you'd rather set the user variables, rather than the system variables

It sounds like you haven't added the right directory to your path.
First find out which directory you've installed Java in. For example, on my box it's in C:\Program Files\java\jdk1.7.0_111. Once you've found it, try running it directly. For example:
c:\> "c:\Program Files\java\jdk1.7.0_11\bin\java" -version
Once you've definitely got the right version, add the bin directory to your PATH environment variable.
Note that you don't need a JAVA_HOME environment variable, and haven't for some time. Some tools may use it - and if you're using one of those, then sure, set it - but if you're just using (say) Eclipse and the command-line java/javac tools, you're fine without it.
1 Yes, this has reminded me that I need to update...

Assume, Java/JDK is installed to the folder: C:\Program Files\Java:
Follow the steps:
Goto Control Panel → System → Advanced system settings → Advanced → Environment variables (Win+Pause/Break for System in Control Panel)
In the System variables section click on New…
In Variable name write: JAVA_HOME
In Variable value write: C:\Program Files\Java\bin, press OK:
In the System variables section double click on Path
Press New and write C:\Program Files\Java\bin, press OK:
In Environment variables window press OK
Restart/Run cmd.exe and write: java --version:

Search environment variables.
open the "edit the system environment variables".
then click on "environment variables".
Under "User variables" click on "Path" then "Edit".
Find your Java path and click "Edit".
then paste the path of your java installation folder.
Mostly you can find it on a path similar to this.
C:\Program Files\Java\jdk-12.0.2\bin
Then click OK.
now in the start menu, type cmd.
open the command prompt.
type
java -version
If you did it right,it should show something like this.

For me its start working after putting ,: in the starting of the system variable path :--

My solution was to put same value (path to JDK bin folder) in JAVA_HOME and Path

In my case, PATH was properly SET but PATHEXT has been cleared by me by mistake with .exe extension. That why window can't find java or anything .exe application from command prompt. Hope it can help someone.

This problem is on Windows 8.
First copy your Path of java jdk - e.g. C:\Program Files\Java\jdk1.7.0_51\bin.
Right on the My Computer Icon on the Desktop and Click Properties.
Select 'Advanced System Settings' in the left pane.
Under 'Advanced' tab, select 'Environment Variables' at the bottom.
In System Variables, select 'Path' Variable and edit it.
Paste the path and add a ';' at the end - e.g. C:\Program Files\Java\jdk1.7.0_51\bin;

I had the same problem. Just Install the exact bit of java as of your computer. If your PC is 64 bit then install 64 bit java. If it is 32 bit then vice versa :)

Not sure why, but in my case, the reason was because I was running Anaconda terminal instead of the CMD.
After I use CMD and update the path settings as mentioned by all comments above the issue solved on my side.

In case you are using a laptop and do not have the Pause\Break button.
For windows 10 users with 20h2 and above:
1 WIN → type "About your PC" → scroll at the bottom → Advanced system settings → Environment variables or WIN+R → shell:::{bb06c0e4-d293-4f75-8a90-cb05b6477eee} to open Classic System Properties → on the left side → Advanced system settings → Environment variables
Also for Windows 10 and Windows 7:
1 WIN → This PC → properties → Advanced system settings → Environment variables
In the System variables section click on New…
In Variable name write: JAVA_HOME
In Variable value write: C:\Program Files\Java\jdk-15.0.2\bin, press OK
I have taken steps 2-4 from Vijay Bhatt
There is a bit faster way to set a system variable. Run a console (terminal) as an administrator.
General command synax to add a new variable:
setx variableName value /M
In our example, we would need to set it as
setx JAVA_HOME "C:\Program Files\Java\jdk-15.0.2\bin" /M`
Like this:
/M - flag specifies to set the variable in the system environment.
After command execution, you should see the message:
SUCCESS: Specified value was saved.
How can I check that it is added?
Close your active terminal;
Open your favorite terminal;
Type java -version.
You should see something similar to this:
Notice:
User variables can be created w/o having a root (administrator privileges), whereas to create System variable; You need to open a console as a root.
I have used C:\Program Files\Java\jdk-15.0.2\bin as an example, in your case, it could be different from mine.

I opened a new command prompt in Windows 10 after updating the environment variables without closing the old one(To have my commands handy and lazy to type again)
Still, the new cmd window was referring to the previous version of Java.
Then once I closed the all cmd prompts that ran with admin privileges, the new java version was getting reflected.

I corrected my path variable but command prompt need to Restart otherwise, it won't be able to verify the change to the path variable. May be helpful for someone like me. so
"restart command prompt"

Restart the command prompt before checking the version of JDK installed. I spent 02 days on it until my problem resolved when I restarted the command prompt before checking javac - version, javac etc.

if you have cygwin installed in the Windows Box, or using UNIX Shell then
Issue bash#which java
This will tell you whether java is in your classpath or NOT.

If you have set the environment variables (JAVA_HOME and PATH) under user variables, command prompt (run as administrator) will not identify java. For that you need to set environment variables under system variables.

Try this:
System variables:
PATH = /bin folder of your jdk install
https://docs.oracle.com/javase/10/install/installation-jdk-and-jre-microsoft-windows-platforms.htm

Just some extra information for people that have still problems,
instead of editing the path variable of java, delete that part of the path(only the java!!)
and make a new variable pointing tpo the jdk/jre.
this seemed to work for me.

Ant is unable to find a javac compiler

I am trying to build some binaries of an application. When i am trying to make the build, I am getting this:
BUILD FAILED
/home/.../ant-build.xml:84: Unable to find a javac compiler;
com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK.
It is currently set to "/usr/lib/jvm/java-8-openjdk-amd64/jre"
The application requires java 7, and i have it installed but i had it along java 8. The build requires for tools.jar which is located in java 7 only, therefore after several attempts i uninstalled java 8. However, when I am trying make again, i get the same error, even though i don't have java8 installed at all!
I set the JAVA_HOME properly:
$ echo $JAVA_HOME
/usr/lib/jvm/java-7-openjdk-amd64/
I doubt i need the path but i set that one up just in case as well :
$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/lib/jvm/java-7-openjdk-amd64/bin
I'm running out of ideas here :P any help would be appreciated.
Also something maybe important, I had to add the repo manually to get java-7 otherwise it wasnt able to locate the package. Thats when i got double jdk-s.

I guess you are calling the JAVAC command from any other source/tool like Jenkins/Bamboo/Teamcity. Make sure you have set the environment variable of that tool. usually it lies in the manage tool option.
I was facing same issue while using Jenkins.If you don't set up an environment variable in tool from which you are making a call it take your
"/usr/lib/jvm/java-8-openjdk-amd64/jre" so go and set the the env variable JAVA_HOME of you tools. attaching screen shot of Jenkins issue. Go to Manage Jenkins -->configure system --> environment variables and set you java_home path.
Cheers

I just encountered the same situation.
That is because JAVA_HOME is not correctly set in sudo environment.
I added export JAVA_HOME=/path/to in /root/.bashrc, and eventually it was built right.

It seems that you are using javac of java8 with JAVA_HOME or CLASS_PATH pointing to java7.
You can use which java to check that.
export JAVA_HOME=/lib/jvm/java-7-openjdk-amd64
export export ${PATH}=${JAVA_HOME}:/bin:${PATH}`

"JAVA_HOME points to an invalid Java installation issue" with service install command in elastic search

I want to use elastic search with my PHP application.
after running service install command , I am getting fallowing error.
C:\elasticsearch-0.90.10\bin>service install
JAVA_HOME points to an invalid Java installation (no java.exe found in "C:\Progr
am Files (x86)\Java\jdk1.7.0_25\bin"). Existing...

Open up and Look into the service.bat file:
It searches for:
%JAVA_HOME%\bin\java.exe
hence your %JAVA_HOME% should not include bin in it.
A workaround if you do not have privileges to set up the environmental variables:
open the service.bat file,
a) Remove the line:
if NOT DEFINED JAVA_HOME goto err
b) Replace %JAVA_HOME% with your java jdk path, something like: C:\Program Files\Java\jdk1.7.0_51
Note: This is just a workaround which works all the time.

from your error message we can see your JAVA_HOME points to
C:\Program Files (x86)\Java\jdk1.7.0_25\bin
while it should point to
C:\Program Files (x86)\Java\jdk1.7.0_25

I think the error message is fairly descriptive , you should look in this folder
is java.exe there ? If not then your JAVA_HOME environment variable to point to the correct installation
heres a page showing how to do that
https://confluence.atlassian.com/display/DOC/Setting+the+JAVA_HOME+Variable+in+Windows
1st hit on google.

Either JAVA_HOME points to the wrong location or you don't have Java installed. Check and see if there's an install of Java in the location specified.
Also note that the JAVA_HOME variable should point to the root of the Java install not the /bin folder. This is being added by the program you're executing.
To change the JAVA_HOME variable to test further use the following in the command prompt:
set JAVA_HOME=c:\xxxx
Once you've established the correct value to use this can be permanently changed in Control Panel>>System>>Advanced System Settings>>Advanced>>Environment Variables

set JAVA_HOME=C:\Program Files (x86)\Java
Above must fix the issue, I came across the same issue while installing the elastic search.
i gave a try by giving "bin" part of path but it did not work, so i just give the top folder "java" in path, it worked.

Just to add my own experience.
i was setting JAVA_HOME using tab autocompletion.
It ends up something like "C:\Program files...:" and it didn't work saying that it cannot find the java program. I solved typing the JAVA_HOME path in the set command without using tab completion. The problem was probably related to the " in the env variable

Problems with server

I am making a game server, and I have to lead it to Java. I have done that, but it says "The system cannot find the path specified. The path is ""c:\programfiles\Java\jdk1.7.0_25" Which I can follow that right to it, with no problems. So whats wrong?
Yes, I have tried a space.

It's very difficult to determine what you are trying to do right here..
From what it looks like, you are trying to call the program, jdk1.7.0_25, when that is not a valid program.
If i'm understanding you correctly, you want to copy all java files from this directory (.) to the jdk folder. to do that, use
#echo off
COLOR 08
title Compiler
cp ./*.java "c:\program files\java\jdk1.7.0_25"
pause
If i'm not correct with that assumption, my second one is that you are trying to compile all java files, and use . as the classpath. If so, then try,
#echo off
COLOR 08
title Compiler
"c:\program files\java\jdk1.7.0_25\bin\javac.exe" -cp . *.java
pause
This is a little dirty from a pragmatic point of view, because you are explicitly stating which version to use.. don't hardcode things like this..
java should be in your path.. if it is not, then press Win+Pause Break click "Advanced Settings -> Environment Variables" and add the "bin" folder to your "PATH" env variable, then you can do
javac -cp . *.java instead of that entire path.

Check your environment variables on your system, as well as the run path from where you are running your server. It may be a configuration issue.
On windows 7, that would be Computer -> Right Click -> Properties -> Advanced -> Environment Variables.
Check to see that JAVA_HOME and/or PATH variable is set.

I am sure you must have tried using / instead of \
In case you have not, please try it.
If it still doesn't work, please provide more details on the error.
You may paste some of the stacktrace if you are getting en exception

How to install Apache Ant?

I want to install SMSlib (http://smslib.org/) in installation instruction (http://code.google.com/p/smslib/wiki/Installation).
In here I must install Apache Ant, but I didn't understand how to do that.
I already download Apache Ant 1.7.1 , read manual (http://ant.apache.org/manual/index.html)
In here I must have RPM version from jpackage.org right? I already go to http://www.jpackage.org/ after that what must I do? I already try (http://mirrors.dotsrc.org/jpackage/1.7/generic/free/repodata/) and (http://www.jpackage.org/browser/browse.php?jppversion=1.7) but too many link. I don't know witch one must I download

If you're on Windows, you can use WinAnt, a Windows installer for Apache Ant that I made.

Step 1: Download and install
Download Ant. Go to the Ant homepage and click to download the binary. Because we’re talking about Windows, choose to download the ZIP file rather than any of the others. Scroll down to where it says “Current release of Ant” and click on the ZIP filename.
Once downloaded, unzip the file. You’ll now need to choose a permanent home for Ant on the computer. c:\java\ant is often used, but you can put it wherever you want.
Step 2: Set environment variables
For Windows XP: To set environment variables on Windows XP, right click on My Computer and select Properties. Then go to the Advanced tab and click the Environment Variables button at the bottom.
For Windows 7: To set environment variables on Windows 7, right click on Computer and select Properties. Click on Advanced System Settings and click the Environment Variables button at the bottom.
The only environment variable that you absolutely need is JAVA_HOME, which tells Ant the location of your JRE.
If you’ve installed the JDK, this is likely
c:\Program Files\Java\jdk1.x.x\jre
on Windows XP and
c:\Program Files(x86)\Java\jdk1.x.x\jre
on Windows 7. You’ll note that both have spaces in their paths, which causes a problem. You need to use the mangled name[3] instead of the complete name. So for Windows XP, use C:\Progra~1\Java\jdk1.x.x\jre and for Windows 7, use C:\Progra~2\Java\jdk1.6.0_26\jre if it’s installed in the Program Files(x86) folder
That alone is enough to get Ant to work, but for convenience, it’s a good idea to add the Ant binary path to the PATH variable.
This variable is a semicolon-delimited list of directories to search for executables. To be able to run ant in any directory, Windows needs to know both the location for the ant binary and for the java binary. You’ll need to add both of these to the end of the PATH variable. For Windows XP, you’ll likely add something like this:
;c:\java\ant\bin;C:\Progra~1\Java\jdk1.x.x\jre\bin
For Windows 7, it will look something like this:
;c:\java\ant\bin;C:\Progra~2\Java\jdk1.x.x\jre\bin
Done
Once you’ve done that and applied the changes, you’ll need to open a new command prompt to see if the variables are set properly. You should be able to simply run ant and see something like this:
Buildfile: build.xml does not exist!
Build failed
That means Ant is installed properly and is looking for a build.xml file.
Source: http://www.nczonline.net/blog/2012/04/12/how-to-install-apache-ant-on-windows/

You can follow these instrunctions-
1)Download the latest version of ant from http://ant.apache.org/bindownload.cgi
2)Unzip and save it to your C:\ directory as ant.
3)Add the bin directory to your PATH environment variable.
4)Add the ANT_HOME environment variable set to C:\ant.
you can use following commands to set ANT_HOME variable
C:>set ANT_HOME=C:\ant
C:>set JAVA_HOME=C:\jdk
C:>set PATH=%ANT_HOME%\bin;%JAVA_HOME%\bin
C:>ant -version
Apache Ant version 1.8.1 compiled on April 30 2010
if you have java installed on your machine
5)Add the ANT_OPTS environment variable set to -Xmx256M.
This is all you need to install ant on your machine.

1) Download "apache-ant-1.8.4-bin.zip" from "http://ant.apache.org/bindownload.cgi"
2) Unzip it and copy "apache-ant-1.8.4" in "c:\Program Files"
3) Right Click "My Computer" -> properties -> Advanced -> Environment variables -> Edit variable "PATH" and append value "C:\Program Files\Java\jdk 1.7.0_04\bin;C:\Program Files\apache-ant-1.8.4\bin" and Click "OK".
4) open cmd and type "ant" for checking.

the installation of ant and smslib is pretty simple. All you need to do is extract it to some directory. Export the path in case of Linux or set the ANT_HOME\bin to the PATH variable to access it from any directory in the shell. ANT_HOME is the root directory where ant is installed.
For SMSLib Download the zip file and this link should guide you on a step by step basis

Sound's like you're using Linux. If so, the easiest way would be to use a package management frontend like Synaptic and install ant in there.

Its very simple just install Apache ant installer for windows give on [link][1]
[1]: http://code.google.com/p/winant/ and all is set.No need to set Environment variables.It will automatically do every thing for you.

You can install Apache Ant with only single command on Ubuntu:
sudo apt install ant
Check the version of ant installed with:
ant -version