Why isn't this work? String value won't change. Recursion

Question

public class ggg
{
static int y=0;
static int x;

static String h;
public static void main(String [] args)
{

    String s = "hadoyef";
    x = s.length();
    System.out.println(s);
    reverse(s);
    System.out.println(s);
}

public static String reverse(String s){

    if (s.length() == 1){
        //System.out.print(s);
        h = h + s.substring(0,1);
        s=h;
        System.out.println(s);
        return s;
    }
    else{
        h = h + s.substring(s.length()-1,s.length());
        return reverse (s.substring(0, s.length()-1));  

        //System.out.print(s.substring(0,1));

    }
}
}

Please help me I dont understand why the s=h; part isn't working. Ignore from here its making me post more detail and idk what to say so im just going to ramble until it works thanks for whoever helps.

read [Is Java “pass-by-reference”?](http://stackoverflow.com/questions/40480/is-java-pass-by-reference) — jlordo, Apr 09 '13 at 17:35

score 5 · Answer 1 · answered Apr 08 '13 at 22:15

5

When you call reverse(s); in main, you're not assigning the result to anything.

answered Apr 08 '13 at 22:15

Bill the Lizard

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@frank You're only calling reverse once in main. You need to print the value returned from it instead of printing `s` again. – Bill the Lizard Apr 08 '13 at 22:49
@frank Its a scope issue. you are saying `s=h` in reverse method which is getting confined to its `String s` variable which is getting collected in method. This is not going to make any impact on `String s` in main. To see effect use `System.out.println(reverse(s));` in your main method. – Smit Apr 08 '13 at 22:51
thank you so much for explaining this to me, smit – frank Apr 08 '13 at 23:01

score 3 · Answer 2 · edited Apr 08 '13 at 23:03

3

You need 2 changes in your code.

Initialize static String h as:
```
static String h = "";
```
Use the return value in main method as:
```
s = reverse(s);
```

edited Apr 08 '13 at 23:03

Beta

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answered Apr 08 '13 at 22:22

prashant

1,805
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score 1 · Answer 3 · answered Apr 08 '13 at 22:16

1

because you are not using result of method reverse(s); why you are returning String when it`s not used ?

answered Apr 08 '13 at 22:16

Martin V.

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its homework and i have to return the string i sent it. – frank Apr 08 '13 at 22:19

Why isn't this work? String value won't change. Recursion

3 Answers3