Andrew Howard Andrew Howard - 3 months ago 11
Java Question

Java error "Value of local variable is not used"

I am really new to java (started learning 2 days ago). Sorry if this is a stupid question. I am trying to learn how to use rt.exec & similar methods so I tried to make a very simple program which runs calc.exe. This is the code:

public class main {
{
try {
Runtime rt = Runtime.getRuntime() ;
Process p = rt.exec("calc.exe") ;
}

catch(Exception exc){/*handle exception*/}
}
}


http://i.stack.imgur.com/KrpsT.png

I get the error " The value of local variable p is not used".

And if I try to compile this is what I get:

http://i.stack.imgur.com/Ryllw.pngI

I think it's easy to fix but I don't know how. Would be nice if someone helped.

Answer

Well, the error "The value of local variable p is not used.", Is not actually an error. It's your IDE (Eclipse), warning you that you aren't actually reading that variable, so you aren't receiving any input from it.

And the other problem with your class is, you don't have a main method. Like this,

public class main {
public static void main(String[] args) {
try {
Runtime rt = Runtime.getRuntime() ;
Process p = rt.exec("calc.exe") ;
} catch(Exception exc){
/*handle exception*/
}
    }
}

And by the way, you should always start a class name with a captial letter. So public class main, should actually be public class Main