How to sort by ASCENDING ASCII CODE?

Question about the task

Symbol frequency

Java Core, Level 8, Lesson 11

Under discussion

I believe I did it but the verification system didn't think so... Great delight if you post your idea, thx

The program is started with one argument: the name of a file that contains text.
Calculate how often each symbol is encountered.
Sort the results by increasing ASCII code (read about it online).

Example:
','=44, 's'=115, 't'=116.

Display the sorted results:
[symbol1] frequency1
[symbol2] frequency2
Close the streams.

Example output:
, 19 - 7 f 361

Requirements:

You don't need to read anything from the console.
Create a stream to read from the file passed as the first argument of the main method.
You need to calculate the frequency of each symbol in the file and display the results.
The displayed results should be sorted by ascending ASCII code.
The stream used to read the file must be closed.

package com.codegym.task.task18.task1821; /* Symbol frequency */ import java.io.FileInputStream; import java.util.HashMap; public class Solution { public static void main(String[] args) throws Exception { String filename = args[0]; FileInputStream inputStream = new FileInputStream(filename); HashMap<Character, Integer> count = new HashMap<>(); while (inputStream.available()>0) { int i = inputStream.read(); if (!count.containsKey((char)i)) count.put((char)i,1); else { int num = count.get((char)i); num++; count.put((char)i,num); } } inputStream.close(); HashMap<Character,Integer> sorted = new HashMap<>(); for (int i = 1; i < 500; i++) { char c = (char)i; if (count.containsKey(c)) sorted.put(c,count.get(c)); } for(HashMap.Entry<Character,Integer> entry : sorted.entrySet()) { if (entry.getValue()!=0) { System.out.println(entry.getKey() + " " + entry.getValue()); } } } }

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Ramen

Level 23 , South Lake Tahoe, United States

6 April 2023, 05:36

I used Collections.sort(array list). But then you have to convert the key from ASCII code back to the original char in the print-out

AlfredW

Level 23 , Denver, United States

4 October 2020, 15:19

If you change your HashMap to a TreeMap it will sort it automatically. So you will be able to remove your entire sorting routine.

MICHAEL DUNLAP

Level 20 , Bellevue, United States

7 October 2019, 03:52

The TreeMap will totally work if you store the ASCII value (as an integer in my case) as the key. Don't store the Character; cast the integer key to a char when you loop through the tree and print the results.

lonelygleaner

Level 22 , New York, United States

11 August 2019, 03:54

Use TreeMap so that the key is sorted when you insert each item in package com.codegym.task.task18.task1821; /* Symbol frequency */ import java.io.*; import java.util.Map; import java.util.TreeMap; public class Solution { public static void main(String[] args) throws Exception{ String fileName = args[0]; FileInputStream fileInputStream = new FileInputStream(fileName); TreeMap<Character, Integer> map = new TreeMap<>(); while(fileInputStream.available() > 0){ int data = fileInputStream.read(); if(map.containsKey((char)data)){ map.put((char)data, map.get((char)data)+1); } else{ map.put((char)data, 1); } } for (Map.Entry mapElement : map.entrySet()) { Character key = (Character)mapElement.getKey(); Integer value = ((int)mapElement.getValue()); System.out.println(key + " " + value); } fileInputStream.close(); } }

Bill Nguyen

Level 22 , Ho Chi Minh, Vietnam

6 August 2019, 05:54

Add ASCII code of characters into a ArrayList, then use Collections.sort(ArrayList). This is my way to pass this problem. Have a nice day!

Switch/Cypher

Level 25 , Bexleyheath, United Kingdom

6 October 2020, 17:47

Me too, sorted in ArrayList then counted in LinkedHashMap to preserve insertion order.

hidden #10361881

Level 19

31 July 2019, 17:33

Actually if you print the ASCII codes in sorted you can see they are not sorted. Here a possible correction:

package com.codegym.task.task18.task1821;

/*
Symbol frequency

*/

import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;

public class Solution {
    public static void main(String[] args) throws Exception {
        String filename = args[0];
        FileInputStream inputStream = new FileInputStream(filename);
        HashMap<Character, Integer> count = new HashMap<>();


        while (inputStream.available()>0) {
            int i = inputStream.read();
            if (!count.containsKey((char)i))
                count.put((char)i,1);
            else {
                int num = count.get((char)i);
                num++;
                count.put((char)i,num);
            }
        }
        inputStream.close();

        ArrayList <Character> sorted = new ArrayList<>(count.keySet());


        Collections.sort(sorted);

        for(int i = 0; i < sorted.size(); i++){

            System.out.println(sorted.get(i) + " " + count.get(sorted.get(i)));
        }

    }
}

Isenraf

Level 20 , Douala, Cameroon

20 August 2019, 01:08

thanks very helpful