Thread: running java files in the cmd.exe

I am Charles Chinedu, a graduate of Statistics, in Nigeria.i picked interest in coding recently, so i took to trraining myself on html5, css, and javascript. i chose to add java to the tutorials i'm getting online. but am having problems running java codes i wrote using notepad in the cmd.exe. this is d code:
public class MyClass {
public static void main(String[] args) {
Systems.out.println("Hello World");
}
}
i saved it with MyClass.java
charset:unicode
what do i need to do to get cmd.exe to recognize the command "javac MyClass.java"

i dont understand this:The command line I posted could be used in any command prompt window.
should i copy and paste the command line in the cmd prompt window.i know my questions will sound silly, but im a beginner. i need help , time flies.

yeah. i know where files are located on my PC. it's located in C:\Users\HP. my java file is in there and still the cmd don't run it.

To compile with javac from the command prompt, the command window needs to know two things: the location of javac.exe and the location of your .java source file(s). From your posts, it appears that "java -version" and "javac -version" are giving good-looking results, which means the Path environment variable is good and thus javac.exe and java.exe can be found without specifying the full path to them.

Next it needs to be able to find your .java file. To do that, you can either CD (change directory) into that folder, then call "javac MyClass.java", or you can specify the full path to the source file without navigating into the folder first (e.g. "javac C:\JavaProjects\MyClass\MyClass.java". When that's successful, you'll see a new file "MyClass.class" file get created next to MyClass.java.

Then you just call "java MyClass" (if the command window is already navigated to the folder containing MyClass.class) or call "java C:\JavaProjects\MyClass\MyClass" (if the command window is not already navigated to the folder) to launch the program. Note for the call to java.exe, we omit the ".class" part of the file we want to execute (since it's implied).

So ultimately there should only be two problems to solve: 1.) Make sure your calls to java and javac are working, not giving errors like "not recognized as an internal or external command" (you can verify this with "java -version" and "javac -version"), and 2.) make sure you're passing (to javac and java) the correct location to your .java file and .class files, respectively. If you "CD" into the directory first, then you're good, otherwise you have to pass the fully-qualified path (e.g. "javac C:\JavaProjects\MyClass\MyClass.java" and "java C:\JavaProjects\MyClass\MyClass")

java version "1.8.0_231"
Java<TM> SE Runtime Environment <build 1.8.0_231-b11>
Java HotSpot<TM> Client VM <build 25.231-b11, mixed mode>

if i have to change the path with the version of java i have, it'd b:
C:\Program Files\Java\...1.8.0_231\bin

i put '...' cos i dont think what i have is jdk, which comes to my second confusion:
can i run my java tutorials with the java i have? "is it jdk?"

>>>><Please copy the full contents of the command prompt window and paste it here so we can see the command that was entered and the response.>
i hv tried copying what i have on the screen of my cmd.exe it doesn't copy.

@Binarydigit09
i hv tried entering "javac -version", its not recognized as an internal, or external command, operable program or batch file

thank you. this is whAT i hv in the cmd.exe:

C:\Users\HP>javac -version
'javac' is not recognized as an internal or external command,
operable program or batch file.

C:\Users\HP>java -version
java version "1.8.0_231"
Java(TM) SE Runtime Environment (build 1.8.0_231-b11)
Java HotSpot(TM) Client VM (build 25.231-b11, mixed mode, sharing)

pls is this jdk or jre(from the name)?

Originally Posted by Chinedu & ICT

thank you. this is whAT i hv in the cmd.exe:

C:\Users\HP>javac -version
'javac' is not recognized as an internal or external command,
operable program or batch file.

C:\Users\HP>java -version
java version "1.8.0_231"
Java(TM) SE Runtime Environment (build 1.8.0_231-b11)
Java HotSpot(TM) Client VM (build 25.231-b11, mixed mode, sharing)

pls is this jdk or jre(from the name)?

There's no way to tell if you have the JDK by simply invoking "java -version", because the JDK comes with the JRE and "java -version" always invokes the JRE, regardless of whether or not you also have the JDK installed. "javac -version" giving errors reveals that the JDK is not installed. "javac -version" is the first thing to get working.

Originally Posted by BinaryDigit09

There's no way to tell if you have the JDK by simply invoking "java -version", because the JDK comes with the JRE and "java -version" always invokes the JRE, regardless of whether or not you also have the JDK installed. "javac -version" giving errors reveals that the JDK is not installed. "javac -version" is the first thing to get working.

thanks alot Binarydigit09!
how do i solve this "javac -version"'s error issue, how do i install the jdk?
i forgot to mention from onset, i have a data-reporting software that runs on java installed in my system. could it be the problem?

Originally Posted by Norm

Go to the Oracle site and download a JDK from there.

do i have to uninstall this jre i have, and also the data reporting app running on java?

Originally Posted by Norm

It is possible to have multiple JDKs and JREs on your PC. The issue would be that the PATH will point to only a bin folder for each program. When wanting to use a program that is not pointed to by the PATH environment variable, you need to give the OS the full path to the program.

i uninstalled other java softs i have and downloaded the jdk 8 update 202 today, the installation since in the afternoon today, based on my time zn is still incomplete. i think its being delayed by bytefence,which has refused to resolve the harmful issues it detected while the jdk setup was running unless i upgrade. however, i downloaded and installed processing. still enjoying the setup() and draw() thrills. but frankly speaking, am not satisfied, cox i want to write java programs, run it, to get the real thrill of it.
i would be grateful if someone can share a jdk setup that would not have bytefence antivirus, a jdk setup that would install smoothly. this is my email:ezeheebochinedu@gmail.com

C:\Users\HP\myJava>javac MyClass.java
MyClass.java:1: error: illegal character: '\u0000'
*■p u b l i c c l a s s M y C l a s s {
^
MyClass.java:1: error: illegal character: '\u0000'
*■p u b l i c c l a s s M y C l a s s {
^
MyClass.java:1: error: illegal character: '\u0000'
*■p u b l i c c l a s s M y C l a s s {
^
MyClass.java:1: error: illegal character: '\u0000'
*■p u b l i c c l a s s M y C l a s s {
^
MyClass.java:2: error: illegal character: '\u0000'

^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal start of expression
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal start of expression
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: ';' expected
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: ';' expected
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal start of expression
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal start of expression
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^
MyClass.java:3: error: ';' expected
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{
^

MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{

^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{

^
MyClass.java:3: error: illegal character: '\u0000'
p u b l i c s t a t i c v o i d m a i n ( S t r i n g [ ] a r g s )
{

^
MyClass.java:4: error: illegal character: '\u0000'

^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: not a statement
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: not a statement
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: ';' expected
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: ';' expected
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:5: error: illegal character: '\u0000'
S y s t e m . o u t . p r i n t l n ( " H e l l o W o r l d " ) ;
^
MyClass.java:6: error: illegal character: '\u0000'

^
MyClass.java:7: error: illegal character: '\u0000'
}
^
MyClass.java:7: error: illegal character: '\u0000'
}
^
MyClass.java:7: error: illegal character: '\u0000'
}
^
MyClass.java:7: error: illegal character: '\u0000'
}
^
MyClass.java:8: error: illegal character: '\u0000'

^
MyClass.java:9: error: illegal character: '\u0000'
}
^
MyClass.java:9: error: illegal character: '\u0000'
}
^
MyClass.java:10: error: illegal character: '\u0000'

^
MyClass.java:11: error: illegal character: '\u0000'

^
MyClass.java:11: error: reached end of file while parsing

^
52 errors

the above is what i'm getting from the cmd when i try to run a program, my javac -version is ok.how do i resolve this issue, i'm reading up java class & classpath to c if i can resolve it. he/she who knows should help me pls.

this is my javac -version:

C:\Users\HP\myJava>javac -version
javac 1.8.0_202

these r d codes i'm trying to run:

MyClass.java

public class MyClass {
public static void main(String[] args) {
System.out.println("Hello World");
}
}

myNum.java

int myNum=33 ;
System.out.println(myNum) ;

Originally Posted by Norm

It looks like the MyClass.java file has been saved as Unicode not text. Edit the file and save it as text.

i c ANSI, unicode, unicode big endian, and utf-8. in "save as type", i c save as text, and all files. i used to save wt unicode, now i save wt utf-8. i edited it now, n changed the save as type from all files to save as text. this is output from the command prompt wn i tried compiling wt "javac MyClass.java":
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Users\HP>javac MyClass.java
javac: file not found: MyClass.java
Usage: javac <options> <source files>
use -help for a list of possible options

i was scavenging on class n classpath, couldn't fully flow with it.
how do i manage ds cmd's output: javac <options> <source files>