Question

Using maps in Java.

Make a public class called ExampleOne that provides a single class (static) method named firstOne. firstOne accepts a String array and returns a map from Strings to Integer.

The map must count the number of passed Strings based on the FIRST letter. For example, with the String array {“banana”, “apples”, “blueberry”, “orange”}, the map should return {“b”:2, “a”:1, “o”:1}. Disregard empty Strings and zero counts.

Retrieve first character of String as a char using charAt, or, substring. You can use any map implementation in java.util. to solve this problem.

Please continue what I have started:

import.util.Map; // I think I need to import HashMap as well?

public class ExampleOne {

public static Map<String, Integer> firstOne(String[] str) {

I’m not sure how to continue. Please write code as simply as possible and provide comments so I can learn from it.

Answer 1

import java.util.HashMap;
import java.util.Map;

public class ExampleOne {
        public static void main(String[] args) {
                String str[]= {"banana", "apples", "blueberry", "orange"};
                System.out.println(firstOne(str));
        }
        public static Map<String, Integer> firstOne(String[] str) {

                Map<String, Integer> map = new HashMap<String, Integer>();

                //Iterating thorugh the given array of strings
                for (String s : str) {
                        //checking if string is empty than not processing
                        if (s.trim().length() == 0)
                                continue;
                        //extracting the first char
                        String firstChar = s.substring(0, 1);
                        //checking if first char is already in the map
                        if (map.containsKey(firstChar)) {
                                //getting the count of that key
                                int count = map.get(firstChar);
                                // updating the key with adding 1 
                                map.put(firstChar, count + 1);
                        } else {
                                // if this is first time than inserting with count as 1
                                map.put(firstChar, 1);
                        }

                }

                return map;
        }
}

NOTE : PLEASE COMMENT BELOW IF YOU HAVE CONCERNS.

I AM HERE TO HELP YOUIF YOU LIKE MY ANSWER PLEASE RATE AND HELP ME IT IS VERY IMP FOR ME