java static void main

Question

Hi to all

I'm trying to print 'hello world' from a java program but I am a little confused with the main method:

public static void main(String[] args)

and

public static void main(string args[])

Both these functions perform the same task. How does this happen?

I know the function of String but not of the args.

Thanks

Answer 1

In Java:

String args[]

is exactly equivalent to:

String[] args

I assume the "string" in your second example is a typo.

Answer 2

You can define an array in Java in two equivalent manners (as you written):

• String[] args
• String args[]

So it doesn't really matters. The first way is a bit more common, though.

Answer 3

You are defining a method named "main" which is public (anyone can call it), static (it's a class method, not an instance method), and returns void (does not return anything), and takes a parameter named args that is a String array.

In Java you can declare a String array as:

String[] args

or

 String args[]

Answer 4

As answered by Sharptooth, it is the parameters passed via the command line when executing the java program.

within your program, you can access these variables via args[0], args[1] etc.

Answer 5

In java your array declaration can be after the type or the name of the variable, so it is ok both methods to perform the same functionality.

args are used to store command line arguments.

Like

java YourClass arg1 arg2

arg1 and arg2 will be stored in args array at indexes args[0] and arg[1].

Answer 6

The args variable is for inputs to your program. See tutorial on command-line arguments.

Answer 7

Im gonna try to explain all the parts of this line public static void main(String[] args)

main: its a Java convention inherited from C.. the first method to run its the one called main.

void: this method should return nothing, which in java its called void

static: you don't need to create an instance of this class to run this method(completely logic if is the first one to run)

public: it is possible to call this method from other classes, even outside of the package(again its logic been the firsts method to be called)

Now to your question String[] args is completely equivalent to String args[] or to String[] name... anyway, it means that args(or name in the last case) its the name of the array of Strings that the method is receiving. Its an array because of the symbols [] and in java is valid to put the symbols in front of the type(String for this case) or in front of the name of the variable(args). If you run your program from a terminal with a command like "java myprogram argument1 argument2" inside the method main the value of args will be args = ["argument1", "argument2"]