How do I return a created Array in Java?

Question

In this program, I'm supposed to count the amount of times the letters 'A','B' and 'C' are in the string and return that as an array. The input is ABBACCCCAC and I'm supposed to get an output of [3, 2, 5] but I'm getting [1, 1, 2, 2, 1, 2, 3, 4, 3, 5]

import java.util.Arrays;
public class HelloWorld{

 public static void main(String []args){
    String str = "ABBACCCCAC";
    int[] arr = new int[str.length()];
    int acount = 0, bcount = 0, ccount = 0;
    
    for(int i =0; i<str.length();i++){
        if(str.charAt(i) == 'A'){
            acount++;
            arr[i] = acount;
        }
        else if(str.charAt(i) == 'B'){
            bcount++;
            arr[i] = bcount;
        }
        else if(str.charAt(i) == 'C'){
            ccount++;
            arr[i] = ccount;
        }
    }
    System.out.print(Arrays.toString(arr));
 }
}

What is your array even supposed to do? You store the current count for whatever letter is at that index up until that point. Ditch the array, and do System.out.print(Arrays.toString(new int[]{acount, bcount, ccount })); — Michael
– Michael, Commented Jul 23, 2020 at 23:54
What is your question? How to return an array? What is wrong with the counting in your array? — user207421
– user207421, Commented Jul 24, 2020 at 0:09

WJS · Accepted Answer · 2020-07-23 23:53:40Z

2

You were close. Just change your array size to 3 and the indiced to 0,1, and 2.

   String str = "ABBACCCCAC";
    int[] arr = new int[3];
    int acount = 0, bcount = 0, ccount = 0;
    
    for(int i =0; i<str.length();i++){
        if(str.charAt(i) == 'A'){
            acount++;
            arr[0] = acount;
        }
        else if(str.charAt(i) == 'B'){
            bcount++;
            arr[1] = bcount;
        }
        else if(str.charAt(i) == 'C'){
            ccount++;
            arr[2] = ccount;
        }
    }
    System.out.print(Arrays.toString(arr));

Your could also just increment the array locations directly.

arr[0]++; // like this.

answered Jul 23, 2020 at 23:53

WJS

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3 Comments

Michael Over a year ago

That being the case, why bother to update the array in the loop at all, when you can construct it after from the counters?

WJS Over a year ago

There are lots of ways to improve this and make it accommodate any number of characters. I was just helping the OP as they may be new at Java.

Michael Over a year ago

I'm not sure that helping them do something illogical is really helping them

Sweeper · Accepted Answer · 2020-07-23 23:57:37Z

0

Right now, you are assigning the counts to the array at each step of the counting, whereas you should have done this at the end of the count. Also, note that you created an array the same length of the string, rather than the expected 3.

You should just move the creation of the array to the end, with an array creation expression:

String str = "ABBACCCCAC";
int acount = 0, bcount = 0, ccount = 0;

for(int i =0; i<str.length();i++){
    if(str.charAt(i) == 'A'){
        acount++;
    }
    else if(str.charAt(i) == 'B'){
        bcount++;
    }
    else if(str.charAt(i) == 'C'){
        ccount++;
    }
}

int[] arr = new int[] { acount, bcount, ccount }; // <--- here!
System.out.print(Arrays.toString(arr));

answered Jul 23, 2020 at 23:57

Sweeper

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