Java recursive loop

Question

I am trying to stop this recursive loop in Java.

I have made a program which prints numbers like Output :1 2 3 4 5 6 5 4 3 2 1 0 1 2 3 4 5 6 5 4 3 2 1

It's like creating a wave of increasing and decreasing numbers. But i want to stop, when it gets more than the length of the string. Can anyone give an alternate way.

boolean isboolean = true;

public void recursive(int data, String s) {
    int counter = 0;

    Loop1:
    while (isboolean) {
        counter++;
        data = data + 1;
        System.out.print(data + " ");
        if (data > 5) {
            isboolean = false;
        }
        if (counter > s.length()) break Loop1;
    }
    Loop2:
    while (!isboolean) {
        data = data - 1;
        System.out.print(data + " ");
        if (data == 0) {
            isboolean = true;
        }
    }
    recursive(data, s);
}

I want to stop this wave of numbers when it gets more than String s length. And prints output: 1 2 3 4 5 6 5 4 3 2 1 0 1 2 3 4 5 6 5 4 3 2 1 but stops, when it's more than string length.

Why are you using labeled loops when you don't have nested loops? — Mushif Ali Nawaz
– Mushif Ali Nawaz, Commented Oct 8, 2019 at 9:18
What do you mean by when it gets more than the length of the string. IF you want to break the recursiveness do a if (data>s.length()) return; Place it as the first line in the add method and it will break. — Ioannis Barakos
– Ioannis Barakos, Commented Oct 8, 2019 at 9:24
@Mushif Ali Nawaz, yes removed that, this is the first time i have posted, so clearly don't have too much idea — Zahid Ansari
– Zahid Ansari, Commented Oct 8, 2019 at 9:28

Bilal Siddiqui · Accepted Answer · 2019-10-08 09:25:31Z

3

With few corrections:

1- declare counter outside

2- make length conditions to both loops

3- stop recursion when length reaches

4- counter should be incremented in both loops.

5- no need for labeled loop now.

boolean isboolean= true;
int counter = 0;

public void add(int data, String s) {

    //Loop1:
    while (isboolean && counter <= s.length()) {
        counter++;
        data = data + 1;
        System.out.print(data + " ");
        if (data > 5) {
            isboolean = false;
        }
    }
    //Loop2:
    while (!isboolean && counter<= s.length()) {
        counter++;
        data = data - 1;
        System.out.print(data + " ");
        if (data == 0) {
            isboolean = true;
        }
    }
    if (counter<=s.length())
        add(data, s);
}

edited Oct 8, 2019 at 9:25

answered Oct 8, 2019 at 9:19

Bilal Siddiqui

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Comments

Mushif Ali Nawaz · Accepted Answer · 2019-10-08 09:48:37Z

A better approach would be to pass the counter value rather than using an error-prone global variable for counter (because it will result in incorrect values if called more than once). And secondly, you can simplify both of your loops into a single loop:

public void recursive(int data, String s, int counter) {
    boolean increment = true;

    while (counter <= s.length()) {
        counter++;
        if (increment)
            data += 1;
        else
            data -= 1;
        System.out.print(data + " ");
        if (increment && data > 5) {
            increment = false;
        } else if (!increment && data == 0) {
            break;
        }
    }

    if (counter <= s.length()) {
        recursive(data, s, counter);
    }
}

And call your method like this:

recursive(0, "abcdefghijklmno", 1);

Output:

1 2 3 4 5 6 5 4 3 2 1 0 1 2 3

Jesper Hustad · Accepted Answer · 2019-10-08 10:21:50Z

0

For your needs you don't need a recursive loop, this will do what you want

So for your needs you would put min as 0 max as 6 and offset as 0:

private static void numberWave(String text, int min, int max, int offset) {
    for (int i = min+offset; i < text.length()+min+offset ; i++) {
        int deltaMX = max-min;
        int counterMod = ((i)%(deltaMX));
        int upWards = min+counterMod+1;
        int downWards = min+(deltaMX-counterMod-1);
        boolean counterPart = (i)%(deltaMX*2)<deltaMX;
        System.out.print((counterPart?upWards:downWards)+" ");
    }
}

Input: numberWave("Hello world" , 0 , 6 , 0 )

Output: 1 2 3 4 5 6 5 4 3 2 1 0 1 2 3

edited Oct 8, 2019 at 10:21

answered Oct 8, 2019 at 9:44

Jesper Hustad

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