How do I run a Java program from the command line on Windows

Question

I m trying to execute a Java program from the command line in Windows  Here is my code   import java io File  import java io FileInputStream  import java io FileOutputStream  import java io IOException  import java io InputStream  import java io OutputStream   public class CopyFile       public static void main String   args                 InputStream inStream   null          OutputStream outStream   null           try                        File afile   new File  input txt                File bfile   new File  inputCopy txt                 inStream   new FileInputStream afile               outStream   new FileOutputStream bfile                byte   buffer   new byte 1024                int length                 copy the file content in bytes             while   length   inStream read buffer    gt  0                                 outStream write buffer  0  length                               inStream close                outStream close                 System out println  File is copied successful                        catch  IOException e                        e printStackTrace                        I m not sure how to execute the program - any help  Is this possible on Windows  Why is it different than another environment  I thought JVM was write once  run anywhere

User · Answer

In case your Java class is in some package. Suppose your Java class named ABC.java is present in com.hello.programs, then you need to run it with the package name.

Compile it in the usual way:

C:\SimpleJavaProject\src\com\hello\programs > javac ABC.java

But to run it, you need to give the package name and then your java class name:

C:\SimpleJavaProject\src > java com.hello.programs.ABC

User · Answer

Source  javaindos      Let s say your file is in C  mywork       Run Command Prompt   C   gt  cd  mywork       This makes C  mywork the current directory   C  mywork gt  dir       This displays the directory contents   You should see   filenamehere java among the files   C  mywork gt  set path  path  C  Program Files Java jdk1 5 0 09 bin       This tells the system where to find JDK programs   C  mywork gt  javac filenamehere java       This runs javac exe  the compiler   You should see nothing but the   next system prompt     C  mywork gt  dir       javac has created the filenamehere class file   You should see   filenamehere java and filenamehere class among the files   C  mywork gt  java filenamehere       This runs the Java interpreter   You should then see your program   output       If the system cannot find javac  check the set path command   If javac   runs but you get errors  check your Java text   If the program   compiles but you get an exception  check the spelling and   capitalization in the file name and the class name and the java   HelloWorld command   Java is case-sensitive

User · Answer

You can compile any java source using javac in command line   eg  javac CopyFile java  To run   java CopyFile  You can also compile all java files using javac   java as long as they re in the same directory  If you re having an issue resulting with  could not find or load main class  you may not have jre in your path  Have a look at this question  Could not find or load main class

User · Answer

It is easy  If you have saved your file as A text first thing you should do is save it as A java  Now it is a Java file    Now you need to open cmd and set path to you A java file before compile it  you can refer this for that   Then you can compile your file using command      javac A java   Then run it using     java A   So that is how you compile and run a java program in cmd  You can also go through these material that is Java in depth lessons  Lot of things you need to understand in Java is covered there for beginners

User · Answer

Now  with JDK 9 onwards   you can just use java  to get that executed  In order to execute  Hello java  containing the main  one can use   java Hello java  You do not need to compile using separately using javac anymore

User · Answer

To complete the answer     The Java File  TheJavaFile java  Compile the Java File to a   class file  javac TheJavaFile java    This will create a TheJavaFile class file  Execution of the Java File  java TheJavaFile  Creation of an executable   jar file   You ve got two options here -   With an external manifest file     Create the manifest file say - MANIFEST mf  The MANIFEST file is nothing but an explicit entry of the Main Class  jar -cvfm TheJavaFile jar MANIFEST mf TheJavaFile class  Executable by Entry Point    jar -cvfe TheJavaFile jar  lt MainClass gt  TheJavaFile class    To run the Jar File  java -jar TheJavaFile jar

User · Answer

Since Java 11  java command line tool has been able to run a single-file source-code directly  e g   java HelloWorld java   This was an enhancement with JEP 330  https   openjdk java net jeps 330  For the details of the usage and the limitations  see the manual of your Java implementation such as one provided by Oracle  https   docs oracle com en java javase 11 tools java html

User · Answer

Complile a Java file to generate a class   javac filename java   Execute the generated class   java filename

User · Answer

STEP 1  FIRST OPEN THE COMMAND PROMPT WHERE YOUR FILE IS LOCATED   right click while pressing shift  STEP 2  THEN USE THE FOLLOWING COMMANDS TO EXECUTE           lets say the file and class name to be executed is named as Student java The example program is in the picture background        javac Student java      java Student

User · Answer

As of Java 9  the JDK includes jshell  a Java REPL   Assuming the JDK 9  bin directory is correctly added to your path  you will be able to simply    Run jshell File java     File java being your file of course   A prompt will open  allowing you to call the main method  jshell gt  File main null   To close the prompt and end the JVM session  use  exit   Full documentation for JShell can be found here

User · Answer

Assuming the file is called  CopyFile java   do the following   javac CopyFile java java -cp   CopyFile   The first line compiles the source code into executable byte code  The second line executes it  first adding the current directory to the class path  just in case

User · Answer

On Windows 7 I had to do the following   quick way   Install JDK http   www oracle com technetwork java javase downloads in windows  browse into  C  Program Files Java jdk1 8 0 91 bin   or wherever the latest version of JDK is installed   hold down shift and right click on a blank area within the window and do  open command window here  and this will give you a command line and access to all the BIN tools   javac  is not by default in the windows system PATH environment variable  Follow comments above about how to compile the file   javac MyFile java  then  java MyFile   https   stackoverflow com a 33149828 194872   long way   Install JDK http   www oracle com technetwork java javase downloads index html After installing  in edits the Windows PATH environment variable and adds the following to the path C  ProgramData Oracle Java javapath  Within this folder are symbolic links to a handful of java executables but  javac  is NOT one of them so when trying to run  javac  from Windows command line it throws an error  I edited the path  Control Panel -  System -  Advanced tab -   Environment Variables     button -  scroll down to  Path   highlight and edit -  replaced the  C  ProgramData Oracle Java javapath  with a direct path to the java BIN folder  C  Program Files Java jdk1 8 0 91 bin   This likely breaks when you upgrade your JDK installation but you have access to all the command line tools now  Follow comments above about how to compile the file   javac MyFile java  then  java MyFile   https   stackoverflow com a 33149828 194872

[java] How do I run a Java program from the command line on Windows?

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