working with the command prompt in Java - java

I've been learning java on my own and I've come to a point where I need to pass arguments from the command prompt. I had previously been using Netbeans, which has become a bit of a crutch, but I want to learn how to program using notepad and the command prompt. I am running Windows 8.1. I downloaded the JDK 7 to my C:\ directory. I tried typing "java -version" and "javac -version" to check it out (as my book says to do) but it tells me "'java' is not recognized as an internal or external command, operable program or batch file." It says the same when I try javac. I do this from C:\ and from C:\Java> and get the same result. I uninstalled Netbeans, thinking maybe it was interfering somehow ... still not working. The book I'm using says it covers Java 7.
I don't understand why it doesn't work. Is there some compatibility issue with Java 7 and win 8.1? My java 7 is update 71 or 72. Did this update change something and now arguments are passed differently? Can anyone help me out? Thank you.

You need to download the JDK (if you don't already have it) and add the location to the end of your PATH. In a single command line session you can do this with PATH=%PATH%;<jdk location> where <jdk location> is the bin folder of the jdk.

Some installs of java manage environment variables and some do not. It appears yours has not. or you have not installed it correctly.
many applications understand JAVA_HOME, so you should set that to the root of the installation in your environment variables.
You will also need to add the bin folder to your path.
Generally, when using windows, you can install a windows exe version, which will manage all of this for you. Other installations just copy themselves to the c drive and expect java applications to know where to look.

Go to System environment variable. Select Variable PATH. Click on edit button. Append a ; after current value of Variable value. Copy jdk's bin folder path. In my PC it is "C:\Program Files\Java\jdk1.8.0_20\bin" without quotes. Then paste jdk's bin path. Copy jre's bin folder path. In my PC it is "C:\Program Files\Java\jdk1.8.0_20\jre\bin". Append a ; then paste jre's bin folder path. Click OK.

Download the JDK from this page. Run the installer.
Open the Command Prompt. Try it. It works. Yay!

If you use the full path to your java.exe, you dont need to set up any PATH and JAVA_HOME:
c:\> cd \work
c:\work> c:\java\bin\java.exe -cp classes\ your.Main
If your book does not use the normal JDK installers it really is supposed to explain that. (However it is normal behaviour for any executable).
(The above example asumes you compile into c:\work\classes\your\Main.class and your JDK is installed (installer does the unpack) in C:\java (typically you would use default locations like C:\Program Files\Java\jdk1.8.0\bin\java.exe).

Related

Javac working with Powershell but not Command Prompt

I am trying to install Java in Windows 10 Home (64 bit). Like many tutorials point out, I downloaded the Java jdk setup file, executed it and once installed changed the Path in the Environment Variables. But for some reason, when I execute the command 'javac' it returns the not internal/external command error in Command Prompt but runs absolutely fine in Powershell. I tried to rectify this by uninstalling Java and reinstalling it very carefully, following all the steps but still this keeps on happening.
Also, during installation of Java, I lost the original value to my Path variable. Could this be causing the problem?
Edit : I was able to get the java command running in the command prompt but javac still won't work. I've already tried the methods suggested on other forums and this one but no luck so far.
See there is no problem with Java installation if you can find JDK(Java development kit) and JRE(Server Java runtime environment) in programme files in windows in a JAVA folder.
The main problem is with the environment variable declaration.
Go to environment variables and make a new path for that.
JAVA_HOME = "YOUR JDK & JRE INSTALLATION PATH"
And another one is
JAVA = "YOUR JDK & JRE INSTALLATION PATH"
Hope that help to you. After doing that if still there problem persisist just restart your PC and check again.
Just add your variable location up to /bin/
Refer to this :
https://www.windows-commandline.com/javac-not-recognized-internal-external-command/
Open file explorer
Right click computer then click properties
click advanced system settings
click environmental variables
click path (for me there was one in user variables for admin and another in system variables)
find the directory for javac (for me it was here C:\Program Files (x86)\Java\jdk1.8.0_191\bin)
so go back to file explorer and open program files x86
then open the java folder
then open the jdk folder
then open the bin folder
highlight the path in the search bar and copy it
click edit on path and paste into the path in the environmental variable for both(if you have more than one path)
If no path exists then create one in user variables
If there is any existing text place a semicolon ; between the text you pasted in there and the preexisting text.
close command prompt and reopen it.
type javac -version
the version info should be listed
This problem comes up with the directory of your command prompt.
check your PowerShell and command prompt default directory.
We can run command prompt as WinKey+R then type cmd, Hit the enter button then check our java version cmd javac -version.

Java jdk path setting in windows

I delete jdk\bin path from environment variables path in windows but when ı write "java -version" in anywhere , it still returns true results . How ?
You can use the where command, to check which java application is executed when you run java -version
Is there an equivalent of 'which' on the Windows command line?
Just type where java in cmd console, and you'll get where it is. And as it shows, I think you need check this location(C:\Windows\System32), when you instal java, Java exe files are copied to windows System32 folder, java.exe, javaw.exe and javaws.exe are available there.
Restart your system and try again. In case, it's still pointing after restart, please check the path variable correctly. Might be some referrence still exist in either system/user path variable and thus giving the result.

setting up classpath. javac is not recognized

I am trying to run my java program from command line.
I read an article about setting up classpath, but I get an error of javac is
not recognized as internal or external command. What should I do? (I dont want to set a permanent CLASSPATH)
This is what I have done in my command line
D:\user> set path=%path%;C:\Program Files\Java\1.7.0_07\bin
D:\user> cd testing
D:\user\testing> javac firstProgram.java
'javac' is not recognized as an internal or external command,
operable program or batch file.
Thank you
Assuming that the PATH is correct1, the most likely cause is that you have a JRE installation ... and a JRE doesn't include a java compiler. You need a JDK installation if you want to compile from the command line.
(You can confirm this by looking in the C:\Program Files\Java\1.7.0_07\bin directory to see if it contains a javac.exe file. A JRE won't ...)
Where can I find the Java compiler to download..
You need to download one of the JDK installers; see http://www.oracle.com/technetwork/java/javase/downloads/index.html
1 - I don't think quotes are required in a PATH variable on Windows. At least that's what various examples that Google found for me seem to imply. But I've never really understood the logic behind quoting in Windows ...
Its an issue related to Program Files.
First make sure that your JDK Folder is installed in Program Files or Program Files(x86) or any other folder.
Then you should use the path of bin folder in " ". Because command prompt does break the string at space. When you will write it in " " then it will take is as a whole String.
You try these commands
set path=%path%;"C:\Program Files\Java\1.7.0_07\bin"
or
set path=%path%;"C:\Program Files(x86)\Java\1.7.0_07\bin"
It might help you to get out of this.
Better do it in Environmental variable and check it!
try below command is recognized from command prompt
C:\Program Files\Java\1.7.0_07\bin\javac ab.java
This is just to verify your javac
Here's how you can set the path temporary, meaning if you close and reopen "command prompt" you will have to set the path again.
Assuming the path is C:\Program Files\Java\jdk1.6.0\bin
TYPE IN C:\Program Files\Java\jdk1.6.0\bin AND HIT ENTER
that's it.
The commands D:\user> set path=%path%;C:\Program Files\Java\1.7.0_07\bin works well for me
Adding few more information to this:
Please check the version of JDK and JRE installed on your computer. Recently I faced the same problem even after setting the PATH. It gives the error "javac - command is not recognised"
Solution is there must be similar versions of JDK as well as JRE
E.g.: JDK 1.7.75 along with JRE 1.7.75

java can run jar from cmd but not by double clicking

I just created a jar file using jdk7. I tried running it but kept getting an error. It turned out it was pointing at a jre6 and not the jre in jdk7. So, I used the following command to change it
ftype jarfile = "C:\path to jre\bin\javaw.exe" -jar "%1" %*
After that, I tried to double click on my jar file again, but it popped up a window asking me to choose a program to open it with. When I chose the same javaw.exe file as above it runs but exits immediately without doing anything. I can run it fine in cmd by doing the java -jar file.jar command. I even tried deleting the .jar registry key, but that just got me back to the point where it asked me to choose a program to open with. I'm running windows 7 ultimate if that matters.
EDIT:
In the registry there are 3 subkeys: OpenWithList, OpenWithProgids, and UserChoice. I've changed all the defaults to the path above except UserChoice which won't let me edit it from regedit. When I delete that and try to run the jar file, it opens up the choose a program to open with window again. For some reason it ignores the other registry keys
OK, I found the answer somewhere else but ran into this issue again so came here via google.
The solution is...
Open up regedit.exe
Either search for "jre6" or follow this: HKLM->SOFTWARE->Classes->jarfile->shell->open->command
Change the Data field to the directory of the javaw.exe file that's in your JDK directory.
For the love of God, don't forget to put the weird [-jar "%1" %*] parts on the end of it.
Enjoy outsmarting Oracle.
Hopefully this'll save some people a bit of time.
This happened to me when I installed the JRE6 plugin for Chrome, though it could happen when installing any other JRE I guess.
I fixed it by going to regedit and searched for jre which brought up...
HKEY_CURRENT_USER/Software/Classes/Applications/javaw.exe/shell/open/command
I changed the REG_SZ
from: "C:\Program Files (x86)\Java\jre7\bin\javaw.exe" "%1"
to: "C:\Program Files (x86)\Java\jre7\bin\javaw.exe" -jar "%1" %*
When windows asks you for a program to run it against it won't insert the needed -jar argument in the command line.
If it's asking you for the exe in which to run it then that means somehow your JRE isn't associated with the .jar extension. You'll need to modify the .jar file registry entry so that it runs c:\path_to_jre\bin\javaw -jar %1 in order for it to work.
It used to be under File Explorer > Tools > Folder Options > File Types.
Then look for .jar in there. You should find a text field that shows the executable to run and the command line arguments. That's what you want to modify. You can also do it in the registry editor too, but I've forgotten the HKEY variable path. I'm sure this KBA will help:
support_microsoft_kb_950505
Check if the file type jarfile is actually registered with the *.jar extension using
assoc .jar
Seems like .jar is not linked to jarfile.
I'm not sure exactly why none of the solutions worked, but I reinstalled jre7 and it works now.
Isn't it easier to change your java version to you rnew jdk7 by changing the CLASSPATH environment variable? See how here

"java -version" not working in command prompt

I downloaded this Java JDK and installed it.
But when I go to the command prompt to check the version, it says it's not recognized.
Is anyone else experiencing this issue with the latest Java?
I might not have installed the right version. I need the java that works with grails
C:\>java
'java' is not recognized as an internal or external command,
operable program or batch file.
C:\>java -version
'java' is not recognized as an internal or external command,
operable program or batch file.
C:\>
when i do a search on my computer for java, it does not find anything
Windows 2k8 R2 server-
For both java [-option] or %JAVA_HOME% to work in the command line you need the following:
In Control Panel->System and Security->System->Advanced system setting->Advanced->Environment Variables->System Variables
Edit the Path variable and add a ";" after the last value and add the the path to the Java bin directory:
e.g.- C:\Progra~2\Java\jre6\bin\
Add the JAVA_HOME Variable with the value set to the path for the java executable:
e.g.- C:\Progra~2\Java\jre6\bin\java.exe
Press simultaneously the "windows" and "pause" buttons on your keyboard, this will bring up the System Preferences dialog.
In the Advanced tab, find Environment Variables.
Then, in the User (upper) section, create or update the following two variables :
JAVA_HOME = where you put your JDK, eg. C:/Java/SDK
PATH = %JAVA_HOME%/bin
Close the dialogs.
Then, in a new command-line console, try "javac -version" and see if it's detected.
It's important that you use a new console, because environment variables are read only when the console is launched.
Java is typically installed (on Windows) as C:\Program Files\Java\jdk<version>
That installation directory has a subdirectory bin which you need to append to your PATH environment variable via the control panel. Then, the commands like java, javac etc. will be available on the command line.
BTW, the same is true for Grails.
Is the -version flag not recognized, or is the "java" command not recognized? One way to test this is just to type 'java' by itself and run it and see what happens.
If the command is not recognized, make sure that the JDK's install path is in your windows PATH. If not, you won't be able to use any of the java executables from the command prompt. Here's another link that may help out.
You need to manually add the path to javac.exe and java.exe to your operating system path. The Java installation program doesn't do that for you.
You most likely don't have java.exe in your system's PATH variable.
For Linux:
check $PATH and $JAVA_HOME. You can configure it in /etc/environment
From console you can check it like:
$ echo $PATH
For Windows:
My Computer -> Properties -> Advanced -> Environment Variables
Check there PATH.
From console you can check it like:
echo %PATH%
You should have a Java icon in Windows Control Panel. Locate the Java tab and click the View button. That will show you the path to the Java executables.
Last but not least, make sure you have restarted the computer so changes in the PATH variable can take effect.
You installed the JDK. Isn't java.exe part of the JRE? Do you have that installed?
Maybe your system variables in the environment variables are not set properly. Follow the steps in the link below. Finally, make sure the path component in system variables has only one JDK path. Delete other JDK paths that you won't use.
https://docs.oracle.com/javase/tutorial/essential/environment/paths.html
You might have installed a previous or older version of Java so you can just uninstall it and directly download JDK from Java JDK
I was also facing the same issue but when I downloaded and installed the latest version the issue was resolved.
Also uninstall any other Java versions which may be present in the program files.
To get to know other versions which may be present in your computer use Windows File Explorer to go to:
Files > Windows C > Program Files > Java
All the JDK and JRE you have will be listed there. Uninstall any other Java versions other than what you installed. And then make sure you have set the path variable of the JDK.
For me, it was incorrect line in the PATH
(1) Check PATH: Type "Edit System Environment Variables" on the search -> System Properties -> Advance -> Environment Variables -> System variables -> Path
(2) On the list, mine was C:\Program Files (x86)\Common Files\Oracle\Java\javapath so I just add \ at the end (the exe files in the javapath folder)
OS: Windows 10 64 bit
IF you set the PATH and it's not showing up in cmd when you run %PATH%, try restarting your computer.

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