How would I print a single index?

Question

So just to give a little direction, Ihave this assignment where I am supposed to print out the reverse of the input. Ex: If someone types in dylan it prints out nalyd. I'm also supposed to accomplish this using for loops and sub strings.

Here's my code:

    Scanner kb = new Scanner (System.in);
    String name;
    System.out.println("What is your name?");
    name = kb.next();
    int x = name.length();
    for (name.substring(x,x); x>-1; x-=1)
    {
        System.out.print(name.substring(x));
    }

This will print out "nanlanylanDylan" but obviously thats not what I want. Just looking for a way to remedy this, I understand I could use other methods like charAt and such but I'm trying to use just substrings.

See here: http://stackoverflow.com/questions/2441501/reverse-each-word-of-hello-world-in-java — Anderson Green, Oct 19 '13 at 01:54

Boann · Answer 1 · 2013-10-19T02:07:02.440

2

String.substring(x) returns the entire string starting at position x until the end. The two-argument form String.substring(begin, end) is what you need to chop out a single character. You should also reduce x by 1 initially to be within range. A fixed version of the loop:

int x = name.length() - 1;
for (name.substring(x,x); x>-1; x-=1)
{
    System.out.print(name.substring(x, x + 1));
}

That extra name.substring(x,x); in the for loop initialization isn't doing anything by the way. A fixed and tidied version of the loop:

for (int x = name.length() - 1; x >= 0; x--)
{
    System.out.print(name.substring(x, x + 1));
}

edited Oct 19 '13 at 02:07

answered Oct 19 '13 at 02:01

Boann

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thank you so much! i had tried ending and starting on x but i didnt think it would be possible to do x-1 – user2769708 Oct 19 '13 at 02:05
To add to this, instead of printing with `System.out.print` you can concatenate with `StringBuffer` – Justin Jasmann Oct 19 '13 at 02:08
@JustinJasmann Indeed, although StringBuffer/StringBuilder already have a `reverse()` method. – Boann Oct 19 '13 at 02:09
@Boann Haha, shhhhhh :P – Justin Jasmann Oct 19 '13 at 02:10

dtgee · Answer 2 · 2013-10-19T02:12:49.790

1

Substring can work much like charAt() if we just substring one character. To do so, we need to get the position of the current letter that we want, and substring that out.

String name;
for (int i = name.length() - 1; i >= 0; i--) {
    System.out.print(name.substring(x, x+1));
}

Note that the first argument to substring() is inclusive, and the second parameter to substring() is exclusive, so we only get one character with parameters (x, x+1).

String name = "John";
name.substring(0, 1); //returns 'J'

edited Oct 19 '13 at 02:12

answered Oct 19 '13 at 02:01

dtgee

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Should be `.length()` not `.length`. – Boann Oct 19 '13 at 02:12

How would I print a single index?

2 Answers2