for loop reading only the last value

Question

There's a bug in my program that makes my loop read only the last part of the inputted string. I want the program to count how many of each character is in a string. I do not want answers telling me how to more efficiently store these values, without repeating everything 26 times. Please answer the question I have stated here instead. Sorry if this is a duplicate! I just don't know what to specify since there is no apparent error.

import java.util.Scanner;

public class stringprogram {
    public static void stringinputmethod()
    {
        Scanner scan = new Scanner(System.in);
        System.out.println("Enter a String");
        String strs = scan.nextLine();

        int numa = 0;
        int numb = 0;
        int numc = 0;
        int numd = 0;
        int nume = 0;
        int numf = 0;
        int numg = 0;
        int numh = 0;
        int numi = 0;
        int numj = 0;
        int numk = 0;
        int numl = 0;
        int numm = 0;
        int numn = 0;
        int numo = 0;
        int nump = 0;
        int numq = 0;
        int numr = 0;
        int nums = 0;
        int numt = 0;
        int numu = 0;
        int numv = 0;
        int numw = 0;
        int numx = 0;
        int numy = 0;
        int numz = 0;

        String randaf;

        for(int i=0; i<=strs.length();i++)
        {
            randaf = strs.substring(i);

            if(randaf.equals("a"))
            {
                numa = numa + 1;
            }
            else if(randaf.equals("b"))
            {
                numb = numb + 1;
            }
            else if(randaf.equals("c"))
            {
                numc = numc + 1;
            }
            else if(randaf.equals("d"))
            {
                numd = numd + 1;
            }
            else if(randaf.equals("e"))
            {
                nume = nume + 1;
            }
            else if(randaf.equals("f"))
            {
                numf = numf + 1;
            }
            else if(randaf.equals("g"))
            {
                numg = numg + 1;
            }
            else if(randaf.equals("h"))
            {
                numh = numh + 1;
            }
            else if(randaf.equals("i"))
            {
                numi = numi + 1;
            }
            else if(randaf.equals("j"))
            {
                numj = numj + 1;
            }
            else if(randaf.equals("k"))
            {
                numk = numk + 1;
            }
            else if(randaf.equals("l"))
            {
                numl = numl + 1;
            }
            else if(randaf.equals("m"))
            {
                numm = numm + 1;
            }
            else if(randaf.equals("n"))
            {
                numn = numn + 1;
            }
            else if(randaf.equals("o"))
            {
                numo = numo + 1;
            }
            else if(randaf.equals("p"))
            {
                nump = nump + 1;
            }
            else if(randaf.equals("q"))
            {
                numq = numq + 1;
            }
            else if(randaf.equals("r"))
            {
                numr = numr + 1;
            }
            else if(randaf.equals("s"))
            {
                nums = nums + 1;
            }
            else if(randaf.equals("t"))
            {
                numt = numt + 1;
            }
            else if(randaf.equals("u"))
            {
                numu = numu + 1;
            }
            else if(randaf.equals("v"))
            {
                numv = numv + 1;
            }
            else if(randaf.equals("w"))
            {
                numw = numw + 1;
            }
            else if(randaf.equals("x"))
            {
                numx = numx + 1;
            }
            else if(randaf.equals("y"))
            {
                numy = numy + 1;
            }
            else if(randaf.equals("z"))
            {
                numz = numz + 1;
            }
        }
        System.out.println("a: "+numa +"\nb: "+ numb +"\nc: "+ numc +"\nd: "+ numd +"\ne: "+ nume +"\nf: "+ numf +"\ng: "+ numg +"\nh: "+ numh +"\ni: "+ numi +"\nj: "+ numj +"\nk: "+ numk +"\nl: "+ numl +"\nm: "+ numm +"\nn: "+ numn +"\no: "+ numo +"\np: "+ nump +"\nq: "+ numq +"\nr: "+ numr +"\ns: "+ nums +"\nt: "+ numt +"\nu: "+ numu +"\nv: "+ numv +"\nw: "+ numw +"\nx: "+ numx +"\ny: "+ numy +"\nz: "+ numz);
    }

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

This code can be shortened 95% by using an array or `HashMap` and for loop. — Hovercraft Full Of Eels, Feb 08 '15 at 18:36
possible duplicate of [Get string character by index - Java](http://stackoverflow.com/questions/11229986/get-string-character-by-index-java) — user253751, Feb 08 '15 at 18:36
not a duplicate, just wrong algorithm to count characters of the string. — Roman C, Feb 08 '15 at 18:44

score 1 · Answer 1 · answered Feb 08 '15 at 18:38

1

The substring method will return a new string from the index specified to the end of the string. What you want is String.charAt(index) which will return the char at the specified location

answered Feb 08 '15 at 18:38

Moddl

360
3
13

Mureinik · Answer 2 · 2015-02-08T19:08:33.303

substring returns the part of the string from the given index to it's end. Since a string longer than a single character can never be equal to a single character, the only place where any of the conditions are met is the last character. Instead of using substring(i) you could use substring(i, i+1), or better yet, charAt(i) - just note that it returns a char primitive, not a java.lang.String object.

Having said that, this entire construct is a bit cumbersome. It would be much easier to use a Map<Character,Integer>:

// Initialization:
Map<Character,Integer> map = new HashMap<>();
for (char c = 'a'; c <= 'z'; ++c) {
    map.put (c, 0);
}

// Going over the string:
for(char c : strs.toCharArray()) {
    Integer i = map.get(c);
    if (i != 0) {
        map.put (c, i + 1);
    }
}

Or an even more optimized form could use an array where the first element indicates the number of 'a's, the second the number of 'b's, etc.:

// Initialization:
int[] chars = new int[26];
for (i = 0; i < chars.length; ++i) {
    chars[i] = 0;
}

// Going over the string:
for(char c : strs.toCharArray()) {
    int i = c - 'a';
    if (i >= 0 && i < chars.length) {
        chars[i]++;
    }
}

score 0 · Answer 3 · answered Feb 08 '15 at 18:47

 randaf = strs.substring(i);

Change this line to

randaf = strs.substring(i,i+1);

And change the for loop to i<strs.length() and not equal to.

If you want to shorten the program you can do this.

int[] counts=new int[26];

for(int i=0;i<strs.length();i++)
counts[strs.charAt(i)-'a']++;

Assuming you only want to count 'a' to 'z'

score -1 · Answer 4 · answered Feb 08 '15 at 18:58

Okay, so I got it right after I posted this. Thanks for helping anyways, though! I just changed the range of my substring to read one character, not all the ones after it as well.

I still did not fix the issue with my long code, but hey, it works.

import java.util.Scanner;

public class stringprogram {
    public static void stringinputmethod()
    {
        Scanner scan = new Scanner(System.in);
        System.out.println("Enter a String");
        String strs = scan.nextLine();

        int numa = 0;
        int numb = 0;
        int numc = 0;
        int numd = 0;
        int nume = 0;
        int numf = 0;
        int numg = 0;
        int numh = 0;
        int numi = 0;
        int numj = 0;
        int numk = 0;
        int numl = 0;
        int numm = 0;
        int numn = 0;
        int numo = 0;
        int nump = 0;
        int numq = 0;
        int numr = 0;
        int nums = 0;
        int numt = 0;
        int numu = 0;
        int numv = 0;
        int numw = 0;
        int numx = 0;
        int numy = 0;
        int numz = 0;

        String randaf;

        for(int i=0; i<=strs.length()-1;i++)
        {
            randaf = strs.substring(i, i+1);

            if(randaf.equals("a"))
            {
                numa = numa + 1;
            }
            else if(randaf.equals("b"))
            {
                numb = numb + 1;
            }
            else if(randaf.equals("c"))
            {
                numc = numc + 1;
            }
            else if(randaf.equals("d"))
            {
                numd = numd + 1;
            }
            else if(randaf.equals("e"))
            {
                nume = nume + 1;
            }
            else if(randaf.equals("f"))
            {
                numf = numf + 1;
            }
            else if(randaf.equals("g"))
            {
                numg = numg + 1;
            }
            else if(randaf.equals("h"))
            {
                numh = numh + 1;
            }
            else if(randaf.equals("i"))
            {
                numi = numi + 1;
            }
            else if(randaf.equals("j"))
            {
                numj = numj + 1;
            }
            else if(randaf.equals("k"))
            {
                numk = numk + 1;
            }
            else if(randaf.equals("l"))
            {
                numl = numl + 1;
            }
            else if(randaf.equals("m"))
            {
                numm = numm + 1;
            }
            else if(randaf.equals("n"))
            {
                numn = numn + 1;
            }
            else if(randaf.equals("o"))
            {
                numo = numo + 1;
            }
            else if(randaf.equals("p"))
            {
                nump = nump + 1;
            }
            else if(randaf.equals("q"))
            {
                numq = numq + 1;
            }
            else if(randaf.equals("r"))
            {
                numr = numr + 1;
            }
            else if(randaf.equals("s"))
            {
                nums = nums + 1;
            }
            else if(randaf.equals("t"))
            {
                numt = numt + 1;
            }
            else if(randaf.equals("u"))
            {
                numu = numu + 1;
            }
            else if(randaf.equals("v"))
            {
                numv = numv + 1;
            }
            else if(randaf.equals("w"))
            {
                numw = numw + 1;
            }
            else if(randaf.equals("x"))
            {
                numx = numx + 1;
            }
            else if(randaf.equals("y"))
            {
                numy = numy + 1;
            }
            else if(randaf.equals("z"))
            {
                numz = numz + 1;
            }
        }
        System.out.println("a: "+numa +"\nb: "+ numb +"\nc: "+ numc +"\nd: "+ numd +"\ne: "+ nume +"\nf: "+ numf +"\ng: "+ numg +"\nh: "+ numh +"\ni: "+ numi +"\nj: "+ numj +"\nk: "+ numk +"\nl: "+ numl +"\nm: "+ numm +"\nn: "+ numn +"\no: "+ numo +"\np: "+ nump +"\nq: "+ numq +"\nr: "+ numr +"\ns: "+ nums +"\nt: "+ numt +"\nu: "+ numu +"\nv: "+ numv +"\nw: "+ numw +"\nx: "+ numx +"\ny: "+ numy +"\nz: "+ numz);
    }

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

for loop reading only the last value

4 Answers4