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Nicholas Ladefoged

Need help with hello world :)

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i am using eclipse to make my first java script. .. the script i made look like this


public class hallo1 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.print("Hello world");
}
}


[size=2]it shows "hello world" in the console inside eclipse, so everything is fine there. im just wondering, how do i take it out of eclipse? (for future scripts) i have tried open it in java. but it closes really fast tryed to print screen to see what it said, and it said it couldnt find my file. i think i have heard i should save it as a jar file to see it? mby im wrong. please help if you can [img]http://public.gamedev.net//public/style_emoticons/default/biggrin.png[/img] or mby just make it open my cmd? if thats possible. [/size]

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[quote name='nico1991' timestamp='1335189955' post='4934100']
[size=2]it shows "hello world" in the console inside eclipse, so everything is fine there. im just wondering, how do i take it out of eclipse? (for future scripts) i have tried open it in java. but it closes really fast tryed to print screen to see what it said, and it said it couldnt find my file. i think i have heard i should save it as a jar file to see it? mby im wrong. please help if you can [img]http://public.gamedev.net//public/style_emoticons/default/biggrin.png[/img] or mby just make it open my cmd? if thats possible. [/size]
[/quote]

You could export your java application, go under File > Export to make a runnable jar... Otherwise, you need to either put the .class file in the system's CLASSPATH path, or you can specify where to find the java .class/.jar/.zip files, by adding the -classpath (or -cp) command line switch in your java command line... Many ways to do it... type java -h to view the command line switches.

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followed your first advice, i got my file with a java icon on it. i double click it, and nothing happens? only possible thing that might be wrong, that i can see is maybe the java program i use to launch isent the right? i use "java platform se binary" [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img] you got any suggestions?

actually something does happen really fast. a cmd opens and closes really fast. captured what it said with a screen shot :) : Error: could not find or load main class c:\users\nico\desktop\var1.jar


btw thanks for your reply. exporting it, so obvious. i just thought i saved it, and tryed to run it as the saved file from eclipse.

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[quote name='nico1991' timestamp='1335199642' post='4934153']
followed your first advice, i got my file with a java icon on it. i double click it, and nothing happens? only possible thing that might be wrong, that i can see is maybe the java program i use to launch isent the right? i use "java platform se binary" [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img] you got any suggestions?

actually something does happen really fast. a cmd opens and closes really fast. captured what it said with a screen shot [img]http://public.gamedev.net//public/style_emoticons/default/smile.png[/img] : Error: could not find or load main class c:\users\nico\desktop\var1.jar


btw thanks for your reply. exporting it, so obvious. i just thought i saved it, and tryed to run it as the saved file from eclipse.
[/quote]

as your application is a commandline application the correct method would be to run it from the commandline (The application is supposed to exit once its printed hello world and for most commandline applications this is a good thing (as they tend to be linked together by shellscripts and artificially pausing them restricts this functionality)

try the command: java hallo1 from the directory that holds the .class file. (you can open a command prompt from windows by running cmd.exe (WindowsButton + R , type cmd.exe , press enter) , use the cd command to change directory to the one holding your class file.

As an alternative, useful only while you're learning and not for real commandline apps you can do something to pause the execution of the application after it has printed hello world:

One method is to read some input:

[code]
public class hallo1 {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.print("Hello world");
InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader reader = new BufferedReader (isr);
System.out.print("Press [Return] to exit");
reader.readLine(); // You can use String s = reader.readLine() instead if you want to be able to do something with any text entered by the user.
}
}
[/code]

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thanks for the replies. what i imagine. is a browser opening when i want to launch what i wrote. but maybe thats just a bit too far out of my league yet :) im very new a programming. so i still have a "hard time" understanding how it works in reality

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