Printing from a dictionary Java

user_8915051 0
Viewed 4408

I would like to print the occurrence of each character in a text using a dictionary system:

Ex: Text is "I like apples"

Console output looks like:

'i' has an occurrence of 2 times on positions: 1, 4

'l' has an occurrence of 2 times on positions: 3, 11

..

So far I've got this

String text = "text";
HashMap<Integer, String> dictionary = new HashMap<Integer, String>();

for (int i = 0; i < text.length(); i++) {
    dictionary.put(i, String.valueOf(text.charAt(i)));
}

Basically just adding each letter to a key value in the dictionary, but I can't figure out how to do the print...

printing dictionary java
3 Answers

This is how I would go about it:

String[] tempArray = data.split("");
IntStream.rangeClosed(1, tempArray.length)            
         .boxed()
         .collect(groupingBy(index -> tempArray[index-1].toUpperCase()))
         .forEach((k, v) -> System.out.println(k + " has an occurrence of " +
                     v.size() + " times on positions " + v.stream()
                    .map(Object::toString).collect(joining(","))));
  • first split the string into their individual characters represented as strings
  • utilise IntStream.range to generate the indices
  • utilise groupingBy to group by the individual characters and have the values as a List<Integer> representing the indices that characters appear in
  • finally, use forEach to format the data and print to the console.

given data is set as follows:

String data = "I like apples";

this yields the output:

P has an occurrence of 2 times on positions 9,10
  has an occurrence of 2 times on positions 2,7
A has an occurrence of 1 times on positions 8
S has an occurrence of 1 times on positions 13
E has an occurrence of 2 times on positions 6,12
I has an occurrence of 2 times on positions 1,4
K has an occurrence of 1 times on positions 5
L has an occurrence of 2 times on positions 3,11

Note that the above solution considers a space as a character as well, if you don't want this in the output then use a filter operation to exclude it:

IntStream.rangeClosed(1, tempArray.length)
         .filter(index -> !tempArray[index-1].trim().isEmpty())
         .boxed()
         .collect(groupingBy(index -> tempArray[index-1].toUpperCase()))
         .forEach((k, v) -> System.out.println(k + " has an occurrence of " +
                     v.size() + " times on positions " + v.stream()
                    .map(Object::toString).collect(joining(","))));
user_58620710

This code uses a dictionary and prints the correct answer in the exact format requested:

import java.util.ArrayList;
import java.util.HashMap;

public class TestDriver {

public static void main(String[] args) {    

    String text = "i like apples";  
    char[] textArray = text.toCharArray();

    //a dictionary that will hold the letter as the key and a list of it's positions as the value.
    HashMap<Character, ArrayList<Integer>> dictionary = new HashMap<Character, ArrayList<Integer>>();

    //loop through the text to check each letter
    for (int i = 0; i < textArray.length; i++) {            

        //if you've already checked this letter, skip to the next one
        if(dictionary.containsKey(textArray[i])) {
            continue;
        }       

        //add the letter's position to its position list
        ArrayList<Integer> positionList = new ArrayList<>();
        positionList.add(i);

        //compare the remaining letters in the text to the current letter
        for (int j = i+1; j < textArray.length; j++) {

                //if a letter matches, add it's position to the list
                if(textArray[i] == textArray[j]) {
                positionList.add(j);
            }   
        }               

        //add the letter and its list of positions to the dictionary
        dictionary.put(textArray[i], positionList);
    }

    //format the response
    for(char key : dictionary.keySet()) {
        ArrayList<Integer> positions = new ArrayList<>();
        positions = dictionary.get(key);
        System.out.println(key + " has an occurance of " + positions.size() + " on positions: " + positions);           
        }
    }
}

Prints to console:

  has an occurance of 2 on positions: [1, 6]
p has an occurance of 2 on positions: [8, 9]
a has an occurance of 1 on positions: [7]
s has an occurance of 1 on positions: [12]
e has an occurance of 2 on positions: [5, 11]
i has an occurance of 2 on positions: [0, 3]
k has an occurance of 1 on positions: [4]
l has an occurance of 2 on positions: [2, 10]
user_104572540

You can try as as below

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class GenericPlayAround {
    public static void main(String[] args) throws InterruptedException {
        String text = "I like apples";
        Map<Character, List<Integer>> dictionary = new HashMap<Character, List<Integer>>();

        for (int i = 1; i <= text.length(); i++) {
            Character c = text.charAt(i-1);
            List<Integer> list;
            if (dictionary.containsKey(c)) {
                list = dictionary.get(c);
            }
            else {
                list = new ArrayList<Integer>();
                dictionary.put(c, list);

            }
            list.add(i);
        }

        System.out.println(dictionary);
    }
}

The output is

{ =[2, 7], p=[9, 10], a=[8], s=[13], e=[6, 12], I=[1], i=[4], k=[5], l=[3, 11]}
user_20742570
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