I'm getting started with java development. So, I installed JRE and JDK in my computer.
Then, I created a simple Example.java file and saved it in my Desktop.
In the prompt, I executed
javac Example.java
and it worked ok. A .class file has been created in my Desktop.
Then, I tried to run the class, executing this:
java Example
and I got an error in a window alert, with this message:
Java Installation Not Completed
Unable to install Java
There are error in the command line switches: "Example";.
Check that the commands are valid and try again
Then, for testing, I executed both commands:
javac -version and
java -version. Both are installed in my computer.
What am I doing wrong?
I am running Windows 8 and have already set my environment variables.
Example.java:
public class Example {
public static void main(String args[]) {
System.out.println("Finally Java");
}
}
Try to remove installation again, look for all leftovers and remove them manually, if you changed the directory you installed java to, remove environment variables as well and set them again. You should also make registry cleanup: https://java.com/en/download/help/manual_regedit.xml Make installation through offline installer.
Related
I made a program in Java on my Macbook. It compiled and executed properly.
I took the .class file and tried to run it in an another machine with windows on it.
I wanted to examine the platform independent feature of Java.
It first gave me Java launcher error and then kept saying, main class not found.
I did run the program on my Mac using the terminal with the following commands javac file.java
and executed it with java classname
Took the class file and tried to run in a windows machine using the command line with the command java classname.
Things did not run then
Has nothing to do with the OS, if java is installed on the windows machine, the class files should run. First make sure you have the JVM installed, if that's not it, it is because your are not running your main class.
Run main from cmd with this command.
java -cp "ClassPath" FileName
I have source code for QR code generation using Java.
I don't know how to run Java in command prompt.
two jar files
E:\QR Code\lib\core-2.2.jar
E:\QR Code\lib\javase-2.2.jar
Java code path
E:\QR Code\src\com\javapapers\java\QRCode.java
Source code
http://javapapers.com/core-java/java-qr-code
Explain me how to run the java in command prompt
Regards
Karthikeyan K
To make sure that Windows can find the Java compiler and interpreter:
Select Start -> Computer -> System Properties -> Advanced system settings Environment Variables -> System variables -> PATH. ...
Prepend C:\Program Files\Java\jdk1.6.0_27\bin; to the beginning of the PATH variable.
Click OK
Then open command prompt and check if Java path setup done by below command
java -version
If everything ok it will show you which Java version you have installed .
then you can run java program Like below a example
C:\test> javac HelloWorld.java
I have test folder and it have HelloWorld.java file inside it after this
C:\test> java HelloWorld
It will give you output in my file i have added below content
public class HelloWorld{
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
Just today I noticed that I can run java in eclipse with no problems but when I try to run it in the command prompt, I get "cannot find or load main class." The command prompt actually compiles all right, and it outputs a .class file, but then it displays the error msg when trying to execute. (Also, I was able to run java in the cmd a couple weeks ago.)
/* work area for practice
*
*/
package Scrap;
public class experimentational {
public static void main (String [] args) {
System.out.println("welcome to java!");
}
}
Found the answer: (i'm using different code but it is still relevant to this problem)
java -cp . hiThere
output: "Hi there"
I know this is classpath but don't know why it works or what the period does for it. Anyone have an idea?
Use:
javac Scrap/experimentational.java
followed by:
java Scrap.experimentational
try java -cp . [your main class].
Did you install a JDK on the machine outside of Eclipse? If you did, then make sure you set your path variables correctly. Open a command prompt (assuming windows) and type java -version
If the JDK was installed properly and path variables were set properly it should tell you the version of Java that was installed. If it tells you that 'java' is not recognized as a command that you do not have a JDK installed, or it was not installed properly.
The reason your program runs in Eclipse is that Eclipse for Java has its own internal JDK and JVM.
Your other option is to set up your path variables to point to Eclispe's internal JDK.
If you were able to run it from a command prompt previously then most likely your class path was altered. Is this a machine at work? Some companies have SMS tasks that come through periodically and restore default system settings (including path variables) to corporate defaults.
Maybe java and javac isn't in your OS path.
If you are using Microsoft Windows in cmd type path and then enter.
If jdk or jre isn't in path you need to put them to it
I had a similar issue when I copy pasted code into an editor. I removed the package declaration on line 1 and it ran then. So I'd investigate above comments on packages, after trying first to remove the package line.
I got a strange problem in my windows 7 system running jdk1.6.0_33
When I try to run a simple java program from command prompt, it opens a new window (something like java frame) and suddenly disappears. There is no result shown on command prompt also I am unable to terminate the process (using Ctrl+C) or close command prompt after this. A java process is created each time I do this. I tried to kill process using Task Manager, but that too didn't work.
I am able to run the same program using eclipse.
Here is my program
class HelloWorld{
public static void main(String [] args)
{
System.out.println("Hello World");
}
}
Environment variables are set as follows:
Path=C:\Program Files\Java\jdk1.6.0_33\bin
classpath=.
Commands I used are,
javac HelloWorld.java
java HelloWorld
Why is this happening? Thanks in Advance.
I'm not sure, but I think this is what happens if you use java versus javaw from the command prompt on Windows:
References:
The java command manual page for Windows.
Difference between java/javaw/javaws
If your java class path is configured correctly.
type javac command in command prompt
You will get java compiler information.
After compile the class find your folder location if any .class file is created.
I'm trying to compile my programs using the command prompt on Windows 7. I'm having a problem when I during compile. I created a test program:
class test
{
public static void main (String args[])
{
System.out.println("this is working!!!!!!");
}
}
I use the following instructions from the command line:
cd \
cd summer
Javac test.java
java test
I have even tried using javaw and I get the same message but in a pop-up box
Could not find the main class, program will exit.
Any suggestions?
It seems your JDK and JVM have different editions.
You are using different versions of JDK. Check the versions on your javac vs java. This error is telling you that your java and compiled class are not same versions. Check your path for configuration, type "set" in dos to see details.
Example: If you compiled your class with javac (version 7) and execute it with java (version 6)