I have the following helloworld class
class HelloWorld {
public static void main (String args[]) {
System.out.println("Hello World");
}
}
This is in an ASCII streamfile on the IFS called helloworld.java. When I try and compile this in QSH I get the following error
javac helloworld.java
helloworld.java:2: ')' expected
public static void main (String args[]) {
¢
I can't see a missing ')' in line 2. I suspect this is a codepage error because I've also never seen ¢ as placeholder on compile output.
Any ideas ?
Personally, I would suggest edit, compile, and test, your java code on a workstation (PC or Mac) and not trying to compile on the IBM i.
It's much more efficient that way.
Once you have code that works the way you want it to on your workstation, create a deployable JAR file and move that to the IBM i for further testing.
Related
in a file named filename.java
class filename{
public static void main(String[] a){
System.out.println("From filename main method");
}
}
public class ClassName{
public static void main(String[] a){
System.out.println("From First main method");
}
}
Observe below commands:
Command 1:
C:\javaDJ>java filename.java
From filename main method
Command 2:
C:\javaDJ>javac filename.java
filename.java:7: error: class ClassName is public, should be declared in a file named ClassName.java
public class ClassName{
^
1 error
Observation:
command 1 compiles (i assume internally ) and executes successfully.
command 2 throws compilation error.
Problem Statement :
How is java cmd able to compile the file called filename.java, when the file(filename.java) contains a public class (ClassName)which is not named 'filename.java' (the name of the file-name.) ?
To highlight a specific section from the JEP#Launch Single-File Source-Code Programs with regards to the behavior
In source-file mode, execution proceeds as follows:
The class to be executed is the first top-level class found in the
source file. It must contain a declaration of the standard public
static void main(String[]) method.
The feature which enabled you to execute Command 1 successfully was introduced in Java 11. The feature allows you to execute a Java source code file directly using the java interpreter. The source code is compiled in memory and then executed by the interpreter, without producing a .class file on disk. Check this for more information.
The error you got in Command 2 has been there since the beginning of Java.
I have been trying to run Java with command line arguments, but for some reason the class can not be found. I am very certain the directory is correct. Is there any way to fix this?
CLDemo.java file
public class Demo {
public static void main(String[] args) {
System.out.print("It works!!!");
}
}
You need to do cd out\production before java CLDemo.
The default compile output of IntelliJ IDEA is under out\production folder, and Java needs to run at the corresponding package (folder) of your compile output.
I am trying to run a simple Java program in Atom, with no success.
My code:
public class Hello {
public static void main(String[] args) {
System.out.println("Hello World");
}
}
I use the cmd-i shortcut to run the code, and get the following error:
javac: invalid flag: /Users/xxxxx/Desktop/Programming/Atom (text editor)/AtomPrograms/AAA first test
Usage: javac
use --help for a list of possible options
[Finished in 0.586s]
The file did not have the same name as the class name.
It runs now.
Thank you
I want to use JOMP API (equivalent to OpenMP in C) but I met some problems:
This is the code I want to run:
import jomp.runtime.*;
public class Hello
{
public static void main (String argv[])
{
int myid;
//omp parallel private(myid)
{
myid = OMP.getThreadNum();
System.out.println("Hello from " + myid);
}
}
}
It is just an hello worl but I have a problem with the compiler. Please have a quick look at this page to understand:
http://www2.epcc.ed.ac.uk/computing/research_activities/jomp/download.html
But I can't, I do not understand how it works... I can only compile it with eclipse default compiler (I guess) and then I have only one thread!
I understand I have to compile this code (in a .jomp file) with
java jomp.compiler.Jomp MyFile
and then compile normally but I can't do this in ecplise neither in the terminal (I do not know how to install this compiler!)
ps: I use Ubuntu 12.04 on a Intel® Core™ i7-3610QM CPU # 2.30GHz × 8.
You just need to add the JOMP parameters to your launch configuration, this example can help you:
JOMP eclipse workaround
I'm just starting Java ... again.
I just made a simple program
class first
{
public static void main()
{
System.out.println("Hello!");
}
}
This runs perfectly fine in BlueJ but it gives an error during run-time when running from command prompt.
This is the error
Exception in thread "main" java.lang.NoSuchMethodError: main
It's because I didn't give String args[] in the main parameter list
Till now, I used to give it subconsciously. I know that the string array contains all the parameter values when running but then why is it running in BlueJ?
(BlueJ is a student-friendly Java editor and compiler)
Your program is valid and will compile to the same thing whether you compile from BlueJ or from the command line.
However, blueJ will let you run any static method in a class (so you can test your functions) where as the command line java command will (only) look for a special main method to run. This main method tages a String array with all the command line parameters and your program should look like this even though you don't use these command line parameters:
class first
{
public static void main(String[] args)
{
System.out.println("Hello!");
}
}