trying to understand the code

[Dana Horst]

Hello guys!
here is the problem to solve : We'll say that a String is xy-balanced if for all the 'x' chars in the string, there exists a 'y' char somewhere later in the string. So "xxy" is balanced, but "xyx" is not. One 'y' can balance multiple 'x's. Return true if the given string is xy-balanced.

xyBalance("aaxbby") → true
xyBalance("aaxbb") → false
xyBalance("yaaxbb") → false

here is the working solution:

public boolean xyBalance(String str) {
boolean y = true; //what is the meaning of boolean here?

for(int i = 0; i < str.length(); i++) {            /
if(Character.toString(str.charAt(i)).equals("x") && y) {  // what
    // the "&&y" means? boolean = true? and what the point? 
y = false;
} else if(Character.toString(str.charAt(i)).equals("y") && !y) {
y = true;
}
}
return y;
} 

please answer the Qs, written in the comments within the code. Thank you!

[Ulf Dittmer]

"boolean" is a primitive datatype like "int". It can take the logical values of "true" or "false".

"&&" is a logical operator - it takes two parameters, and evaluates their logical "AND".

Here's the chapter in Oracle's tutorial that covers both these: http://docs.oracle.com/javase/tutorial/java/nutsandbolts/index.html

[Paweł Baczyński]

Nah, that solution is not optimal (if it works -- I didn't even check).
Why not just check last index of 'x' (lastX).
If lastX < 0 that means 'x' is not present in a String so the String is balanced.
Else, get last index of 'y' (lastY).
If lastY > lastX return true,
else return false.

[Winston Gutkowski]

Dana Horst wrote:please answer the Qs, written in the comments within the code. Thank you!

Dana,

Please DontWriteLongLines. It makes your thread very hard to read, and it's actually bad coding practice.
I've broken yours up this time, but for future reference, please remember:
80 characters max.
(the SSCCE page actually recommends 62)
And that includes string literals and long method calls AND comments.

Thanks.

Winston