Java occurrences of the given char in Array

Question

This is my homework, I am trying to get the occurrences of 'e' in strings of the array. My method doesn't seem to work. Can anyone wise person advise where did I go wrong?

import java.util.*;
import java.lang.*;
import java.io.*;

public class CountChar {
    public static void main(String[] args) {
        String[] strings
                = {"hidden", "Java SDK", "DDD", "parameter", "polymorphism", "dictated", "dodged", "cats and dogs"};
        int result = numberOfCharacters(strings, 'e');
        System.out.println("No. of occurrences of 'e' is " + result);
    }

    public static String numberOfCharacters(String str, char a) {
        int aresult = 0;
        if (str.length() > 0) {
            aresult = count(str.substring(1), a) + (str.charAt(0) == a ? 1 : 0);
        }
        return aresult;
    }    
}

You are passing a `String[]` as an argument to `String` type parameter. Change the method parameter to `String[]`. — Rohit Jain, Jan 18 '14 at 12:30
Your method is written to work with a string not an array of string. You can keep your method as it is and call this method for every string in the array and save the sum in an variable. Then print the sum — Marco Acierno, Jan 18 '14 at 12:57

score 1 · Answer 1 · answered Jan 18 '14 at 12:33

1

Just change your method signature to:

public static String numberOfCharacters(String[] str, char a) {

///code
}

answered Jan 18 '14 at 12:33

Raj

600
1
5
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1

I tried , but " int result = numberOfCharacters(strings, 'e');" show error 'incompatible type' – user3203056 Jan 18 '14 at 12:45
obviously it will say you are returning integer and the return type is string. – Vinayak Pingale Jan 18 '14 at 13:12

Vinayak Pingale · Answer 2 · 2014-01-18T14:30:52.437

0

+1 for santosh's answer. I have tried it in following way . Try it out

public class CountChar {
public static void main(String[] args) {
    String[] strings
            = {"hidden", "Java SDK", "DDD", "parameter", "polymorphism", 
               "eeeee", "dodged", "cats and dogs"};
    int result = 0;
    for(int i=0;i<strings.length;i++) {
        result += numberOfCharacters(strings[i], 'e');
    }
    System.out.println("No. of occurrences of 'e' in String is "+ result);
}
public static int numberOfCharacters(String str, char a) {
    int counter = 0;
    for( int i=0; i<str.length(); i++ ) {
        if( str.charAt(i)== a ) {
            counter++;
        } 
    }
    return counter;
}

}

edited Jan 18 '14 at 14:30

answered Jan 18 '14 at 13:05

Vinayak Pingale

1,315
8
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why? do you want it to be outside the for loop. I want to display every string array element and occurence of e in that. – Vinayak Pingale Jan 18 '14 at 13:17
1

because he asks for the number of occurrences in the whole array and you print the number of occurrences in each word. :) – Raul Guiu Jan 18 '14 at 13:44
1

oh yes, a slight modification. please check. – Vinayak Pingale Jan 18 '14 at 14:31

score 0 · Answer 3 · edited May 23 '17 at 11:49

In one liner:

Arrays.toString(strArray).replaceAll("[^"+a+"]", "").length();

Where 'a' is the char and 'strArray' the array of strings.

Using idea on how to count chars in a String from this question:

Java: How do I count the number of occurrences of a char in a String?

Complete code:

import java.util.Arrays;
public class CountChar {
    public static void main(String[] args) {
        String[] strings
                = {"hidden", "Java SDK", "DDD", "parameter", "polymorphism",
                  "eeeee", "dodged", "cats and dogs"};
        System.out.println("No. of occurrences of 'e' is " + 
                            countCharsInArray(strings, 'e'));
    }

    public static int countCharsInArray(String strArray[], char a) {
        return Arrays.toString(strArray).replaceAll("[^"+a+"]", "").length();
    }
}

Explaining it:

'Arrays.toString(strArray)' converts the array into a single string. 'replaceAll("[^"+a+"]", "")' replace all characters that are not the one we want by empty char '',

After that we only need to check the length of the resulting string.

Note: The array should not have nulls, or they should be removed first.

Perfect ! You are gooooood . Thank you so much for the explanation. — user3203056, Jan 18 '14 at 15:11

Java occurrences of the given char in Array

3 Answers3