loop for please explain?

Posted on 2004-08-10
Medium Priority
Last Modified: 2010-03-31
i am reading this tutorial on java.sun.com and i have problem understanding this program

1 public class BasicsDemo {
2    public static void main(String[] args) {          
3        int sum = 0;
4        for (int current = 1; current <= 10; current++) {
5            sum += current;
6        }
7        System.out.println("Sum = " + sum);
8    }
9  }

i don't understand the following:

line 2 "what is (String[]args) and why is there void in the main function
line 4 & 5 can you explain the loop how does it work because the sum = 55 and i don't know how the number is getting there i just cannot understand the equation and the way the loop works Please explain that loop to me as best as you can

I am just begining in java i found tutorials on java.about.com and java.sun.com

is there any other good sites that you guys know about  

thank you  
Question by:macipod
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LVL 14

Assisted Solution

sudhakar_koundinya earned 500 total points
ID: 11764532
line two explains you that, it is starting method of your java class

generally syntax of main is  RDT static main(String s[])

RDT-> is return data type void means this method will not return any thing

coming to your loop it is calculating

It is just printing the sum of first 10 integeres


Accepted Solution

Nick_72 earned 500 total points
ID: 11764559

>>line 2 "what is (String[]args) and why is there void in the main function

the args parameter is an array of strings which contains any parameters you sent to the applications when it was started (for example from the commandline you could use:  java myApplication parameter1 parameter2).
The first position in the args array would contain "parameter1" and the second position in the array would contain "parameter2". Of course, if no parameters are sent, the length of args is 0.
The main method is declared void since it never has a return value.

The loop:

The variable sum is declared as 0, and the loop value (current) starts at 1 and loops as long as current is less or equal to 10, and in every loop it adds its value to the sum variable.
Thus, it's equal to writing:

1+2+3+4+5+6+7+8+9+10 = 55.

Hope it helps,

LVL 14

Expert Comment

ID: 11764562

Expert Comment

ID: 11764635
sum += current;

is equal to:

sum = sum + current;

Expert Comment

ID: 14493036
good job guys

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