very beginner ques 1

[Nanda]

Hi,

Could anybody please tell me what is wrong in the following statement....i get error when i compile.

int x = args[0];
int y = args[1];
System.out.println(x + y);

Thanks in advance

 

[Kruzer]

try this - I don't what error you got, but here yah go

int x;
int y;
int [] args = new int[3];
args[0] = 1;
args[1] = 2;
x = args[0];
y = args[1];
System.out.println(x + y);
Dano
dskryzer@hotmail.com
What's your major malfunction

 

[Nanda]

Apologies, I did not explained my prob...actually, I am trying to sum 2 numbers passed at command line...here args is command line argument. I think main function can only contain String args. I am not at all sure.
my code is

public class Sum {
public static void main(String[] args)
{
// sum to numbers
int x = args[0];
int y = args[1];
System.out.println(x + y);

}
}
and error on compilation is "Incompatible type of declration. Can't convert java.lang.String to int"
I know args is string and my x and y are int. But, how do i solve it?

 

[globos]

Hi,

Maybe you have already solve your problem, but I will give you a solution.

You just have to convert the strings to ints as you might expect.
So, simply do :

public class Sum {
public static void main(String[] args)
{
int x = Integer.parseInt (args[0]);
int y = Integer.parseInt (args[1]);
System.out.println(x + y);
}
}

Bye

 

[Guest_imported]

What ever you enter through Command Prompt we won't receive
it as integer.So you do casting to integer and the add it. It will work definetly.

 

[Nanda]

Thank you all for your reply and time. I was not able to figure out, how to do casting. It solved my problem.

Now, to do any casting, will the syntax be always same
float x = Float.parseFloat(argu[0]); OR
Int y = 3;
String s = String.parseChar;

or it will be different. I am also bit confused with when to use Int and when Integer, when char and when String. Kind of I am confused with types and its conversions. any comments will be a guideline for me.

Thanks again.
Nanda

 

[globos]

Hi Nanda,

What we are talking about is not casting, but logical representations between very different types (i.e. String and int). You talk about casting when conversion between types has a "semantic" sense (casting a float to an int has sense, but casting a String to an int has no sense).
We often talk about "primitive casting". Primitives in the Java language are : char, byte, short, int, long, float, double, boolean, and void.
You might have heard that everything in Java is object, indeed classes instance. Objects are always created in a memory area which is not optimal. But the Java language has particular elements which are called primitives. Primitives look like objects, but are not objects at all. They are created and managed in a different way(for example int primitive is useful for loop counters). However, primitives are wrapped into objects specially made for that, such objects are called wrappers.
Integer, Float classes, for example are wrappers for primitives int and float respectively. They just provide helpful features to manage their corresponding primitives.

I hope this could help you. --
Globos

 

[Nanda]

Thank you Globos...you explained well in short. Thank you.

Nanda