Develop Reference

java -cp/javac doesn't work in cmd prompt

I am trying to run mo program by cmd :
first i try to compile my Main.java by "javac Main.java", after that i have no msg in cmd
second i run "java -cp Main"(Main.class with byte code), after that i have no output in cmd
I tryed reinstall my JDK, but it doesn't help. also when i run "java -version" in cmd i have no output. and no msg.I has set my JAVA_HOME path into JDK dir and set him into my PATH "%JAVA_HOME\bin". what i cant do wrong? Pls help

Your path environment variable for java is not set correctly. You could try to run the command where java and most likely it will return a path that is not correct (or nothing).
Find the correct path where your JDK is installed and run this command to add it to the path vars in cmd:
set PATH=%PATH%;C:\your\path\here\
An example for my system and path would be:
set PATH=%PATH%;C:\Program Files\Java\jdk-11\bin
After setting this path variable, close and reopen your cmd window and try running java -version again.
If it still doesn't show anything then you have to manually change your path variables and remove the old path.

Make sure that you have correctly set the path to the directory in which you have your java installed. For instance mine is settled in D:\Program files\java\jdk-11.0.2
Subsequently I set JAVA_HOME as
Then you open path variable and new entry as following:
Then save all changes. Close all running cmd, start it again and then retry java -version

java is not recognized as an internal or external command, variables are set already

After setting JAVA_HOME to C:\Program Files\Java\jdk1.8.0_171 and adding %JAVA_HOME%\bin to my path, I am still getting this error. I have checked that the path is correct multiple times and every solution online just says to add these two variables. Is there any other step to fix this?
I'm getting this error when trying to run "java -jar start.jar" for solr.

You have not added Java Location as the Path variable in your system. The Command Prompt or Powershell can only take you to the path/paths you have already specified.
Add "C:\Program Files\Java\jdk1.8.0_171\bin\" to the Path variable in your Advanced System Settings->Enviroment Variables->Path.

Make sure you run the command in a new DOS shell. If you are using the same one you ran the java command in before setting the path, it won't have the path update.

Don't type path manualy - choose path by [Browse directory] button.
Path looks the same but can be different (maybe encoding of signs)

Even when I defined the class path, javac is not recognizing it

I am using Windows 7 and 8 in my PC .
I have installed jdk 7 and created class path for bin as it should be. But when I enter javac in the command prompt, it throws an error:
`javac is not recognizing as internal and external`.
I have searched for a solution in many websites but nothing could solve my problem.
Would you please help me and suggest where my mistake could be?

You need to set the environmental variables. Run sysdm.cpl from run dialog box to open advanced system properties.
In the environmental variables, add a new one like in this dialog.
Name : JAVA_HOME
VALUE: C:\Program Files\Java\jdk1.7.0_21\
Now edit the value of the PATH variable and add ;%JAVA_HOME%\bin\; at the end of it's value.
Now, restart your system and you can run java related commands from command prompt.

also set path in your *System variables:path=c:/..../jdk/bin/;c:/..../JRE/bin;.;
user Variables:CLASSPATH=c:/..../jdk/bin/;c:/..../JRE/bin;.;

Double check your system variable "Path" on System Properties appending %PATH_TO_JDK%\bin. Don't forget to restart the command prompt after.

It is path not classpath - -till your bin folder
and restart cmd

Javac Command Not Working

My javac command is not working.
"javac is not recognized as an internal or external command, operable program or batch file."
-java version WORKS
I've tried setting classpath successfully in command prompt. SET CLASSPATH "C:\Program Files\Java\jdk1.7.0_09\bin";
Ive adding it in environment variables. ;C:\Program Files\Java\jdk1.7.0_09\bin ;C:\Program Files\Java\jre7\bin
Ive checked the bin folder java.exe is there aswell as javac.exe.
^ Tried all of these still doesn't work. I've also restarted command prompt still does not not work.
Why is not working?

You're using the correct path apparently, but you should assign it to the PATH variable, not to the CLASSPATH variable.
You're trying to set the access path to the executable files, not to the class files.

Just do this
In the same dialog, make sure that JAVA_HOME exists in your user variables or in the system variables and it is set to the location of your JDK,
e.g. C:\Program Files\Java\jdk1.5.0_02 and that %JAVA_HOME%\bin is in your Path environment variable.

Just set JAVA_HOME to
C:\Program Files\Java\jdk1.7.0_09

After adding the path to the jre7\bin-Folder to the PATH-Variable, you need to restart your Computer in most cases.

Did you tried to create a JAVA_HOME variable? The value should be the path of the java without the bin.
Also, try to open Eclipse.
If nothing helps, the last thing that you can do is install netbeans, it will configurate everything.

javac command prompt parameters

I installed java on my machine and I wanted to compile this group of source code. But when I opened up the command prompt and typed in javac, the command prompt said it was an unknown parameter. The same thing happened when I wanted to build something with ant (I had the build.xml if you are wondering) and the same thing happened. How can I set the javac and ant command to be used in any directory?

First of all you have to be sure you installed JDK and not only JRE
Secondly it depends on your operating system:
windows: you have to reach environment variables by using My Computer (manage->advanced->something here)
linux/osx: you have to export variables with export command or by using a .profile file in user directory
Then you need to set two things:
adding /jdk_1.6.../bin/ to your PATH variable
setting JAVA_HOME to your root of java installation ( /java_1.6..../ ) (maybe this is not required by java itself but many frameworks use it)
One note: on OSX, and maybe Linux too you have to split paths in PATH variable with double colon ':' instead that semicolon ';'

Add the directory the executable is in to the PATH environment variable.

Guessing that you are using Windows. Right click My Computer and click Manage. Then, in the Advanced tab, select Environment Variables. In the new window, under System variables, find Path and append the full path to the binaries (javac and ant) at the end, separated by semicolons.