An odd warning and a problem...

[boen_robot]

I'm working with JAVA these days, part of efforts for impoving my API, but before going into the deep, I wanted to learn some basic JAVA I/O, and one that would work from PHP as well. Standard byte streams seem to be it.The program below is supposed to be like "echo" a bit. You write something (for example "test"), and get "Default string."+the text you typed (example: "Default string. test").

public class Main {	public static void main(String[] args) {		try {			boolean keepReading = true;			java.util.ArrayList line = new java.util.ArrayList();			while(keepReading) {				int character = System.in.read();				if (character != '\n') {					line.add(line.size(), character);				}else {					String lineContents = "Default string. ";					for(int i = 0; i<line.size(); i++) {						lineContents.concat(new String(line.get(i).toString()));					}					System.out.println(lineContents);					System.exit(0);				}			}		}	}}

The problem is instead I always get only "Default string. ". The for loop doesn't seem to be working, or... something else, I don't know for sure. What could possibly be the reason?Also, at compile time, I get the warning:Main.java:18: warning: [unchecked] unchecked call to add(int,E) as a member of the raw type java.util.ArrayListwith line 18 being

					line.add(line.size(), character);

What on earth does this warning mean? How could I avoid it and what problems could this cause? Is it possible its related to the fact I don't see anything from the input?If I'm taking the wrong approach, how would you suggest I echo out something from the input stream? Oh, and no console allowed. PHP doesn't support it, I've tried.

[boen_robot]

Nevermind. Got my question answered elsewhere. Shows how much W3Schools needs a JAVA forum.

[Synook]

"immutable"... being grown with PHP where there's no such thing, I think this is one word I'll keep hating for a long, long time.

What about constants?

[boen_robot]

What about constants?

When I use constants, I use them exactly because I don't want thir values to change. In JAVA, when I use Strings, I use them because that's the better way of representing characters than a sequence of bytes, but I still want them to be changeable, hence they are stored in a variable (which I'd expect by defintion, to be able to vary). The same goes with Arrays. I use ArrayList objects in preference of Arrays because they're not immutable like arrays.