while loop question

JavaBeans

failed a beginners java module, so Im doing some revision for my repeat in august, kinda stuck here if anyone can help please....


write a method called reverseString that takes a string s, passed to it as a parameter, and reverses the string. You should use a while loop to display one character at a time.

use the header: public void reverseString(String s)


here's what I have, yes it's a looks like a dog's dinner, can someone fix it for me thanks

public void reverseString(String s)
{
        String answer = "" ;
        int i = 0 ;
        int j = 0 ;
        while(i <= s.length()){
            while(j >= 0){
                answer = s.substring(i); 
            }i--  ;
            j++ ;
        }
System.out.println(i) ;

    }

boblong

Something like this?

public class Main {
	
	public static void main(String[] args) {
		reverseString("Hello JavaBeans!");
	}
	
	public static void reverseString(String s) {
		int i = s.length()-1;
		
		while (i>-1) {
			System.out.println(s.charAt(i));
			i--;
		}
	}

}

Although the question wording sort of implies that a reversed string should be returned, the return type of 'void' in the prototype suggests otherwise...

JavaBeans

hey, thanks for reply, ive slightly modified what you wrote, and now it works,
but we haven't covered charAT method you've called !! but it works !! ill learn it off thanks..Im sure ill be back with more questions as i redo the course work

http://i55.tinypic.com/11tlsu8.jpg

boblong

Cool, glad it worked out.

Note that the i>-1 terminating condition will also work, as:

i=5 (ok)
i=4 (ok)
i=3 (ok)
i=2 (ok)
i=1 (ok)
i=0 (ok)
i=-1 (Not OK as i is not > -1)

but43r

JavaBeans wrote: »

but we haven't covered charAT method you've called !!
http://i55.tinypic.com/11tlsu8.jpg

You will NEVER cover all methods available in JAVA API in college and I am sure you are not restricted to use particular methods when doing coursework. I would suggest you to have a look at JAVA API - http://download.oracle.com/javase/6/docs/api/

stesh

but43r wrote: »

You will NEVER cover all methods available in JAVA API in college and I am sure you are not restricted to use particular methods when doing coursework. I would suggest you to have a look at JAVA API - http://download.oracle.com/javase/6/docs/api/

JAVA API is best API.

Placebo

http://www.irt.org/script/1325.htm

lynchie

Placebo wrote: »

http://www.irt.org/script/1325.htm

Above code is javascript, not java and does not demonstrate a while loop.

JavaBeans

but43r wrote: »

You will NEVER cover all methods available in JAVA API in college and I am sure you are not restricted to use particular methods when doing coursework.

probably not, but the exercises given to us we're specifcally to get us used to while loops, and solve problems with while loops, Im aware of the api cheers !

like my lecturer would of wanted this as the answer..

public void reverseString(String s)
{
String answer = "" ;
int i = s.length() ;
int j = 0 ;
while(i >= 0){
while(j < s.length()){
answer = s.substring(i);
}i-- ;
j++ ;
}
System.out.println(i) ;

}