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Question about the task

Longest sequence

Java Syntax, Level 8, Lesson 6

Resolved

This my code:

1. Create a list of numbers.
2. Use the keyboard to add 10 numbers to the list.
3. Display the length of the longest sequence of repeating numbers in the list.

Example for the list 2, 4, 4, 4, 8, 8, 4, 12, 12, 14:
3

The value is 3, because the longest sequence of repeating numbers is three fours.

Requirements:

The program must display a number on the screen.
The program should read values from the keyboard.
In the main method, declare an ArrayList variable with Integer elements and immediately initialize it.
The program should add 10 numbers to the collection in accordance with the conditions.
The program should display the length of the longest sequence of repeating numbers in the list.

package com.codegym.task.task08.task0812; import java.io.*; import java.util.ArrayList; /* Longest sequence */ public class Solution { public static void main(String[] args) throws IOException { // Create list of numbers ArrayList<Integer>list = new ArrayList<>(); BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); // Add 10 numbers to the list for (int i = 0 ; i < 10 ; i++){ int n = Integer.parseInt(reader.readLine()); list.add(n); } // Display the length long sequence int count = 1; int maxCount = 1; for (int i = 1 ; i < 10 ; i++){ if ( list.get(i-1) != list.get(i)){ count = 1; } else count ++; if (maxCount < count){ maxCount = count; } } System.out.println(count); } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

12 April 2019, 13:30

public class Solution {
    static class debug{ // debug flag: True equals 'debug' mode, false normal mode
        static public boolean flag(){
            return true; // set to false before verifying
        }
    }

    public static void main(String[] args) throws IOException {
        // Create list of numbers
        int[] n = {1,1,1,1,4,5,5,6,6,6};
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        ArrayList<Integer>list = new ArrayList<>();

        // Add 10 numbers to the list
        for (int i = 0 ; i < 10 ; i++){
            if(debug.flag())
                list.add(n[i]);
            else list.add(Integer.parseInt(reader.readLine()));
        }
        // Display the length long sequence
        int count = 1;
        int maxCount = 1;

        for (int i = 1 ; i < 10 ; i++){
            if(debug.flag()){
                System.out.print("Testing indice [" + (i-1) + "] and [" + i +"]: ");
                System.out.println(list.get(i)+" =? " + list.get(i-1) );
            }
            if ( list.get(i-1) != list.get(i)){
                count = 1;
                 if(debug.flag()) System.out.println("\tNo match =( - setting count to "+ count);
            }
            else {
                count++;
                if(debug.flag()) System.out.println("\tMatch!! =) - count now " + count);
            }
            if (maxCount < count){
                maxCount = count;
                if(debug.flag()) System.out.println("\tcount greater than maxCount, setting maxCount to: " + maxCount);
            }
        }

         if(debug.flag()) System.out.println("maxCount: " + maxCount + " -- count: " + count);
        else
        System.out.println(count);
    }
}

Guadalupe Gagnon

Level 37 , Tampa, United States

12 April 2019, 13:55

solution

Being able to debug your code (or others) is one of the most beneficial skills to have. Take a look at the code that I shared, which is your code modified for 'debug' mode. Basically you set ONE boolean value to use throughout your code. When that value is true then debug mode is activated, when that value is false then debug mode is shut off. First lines 10 along with 15-19 have been added or changed to use an array of numbers. This array is to signify user input, but is used when debug mode is activated so you don't have to manually enter numbers every time you want to test run your code. Change the numbers in the array on line 10 to anything you want to test. You then put a bunch of conditional if statements through out the code with Sys.out lines that you can use to output information about the status of the program. When the code is run it will output a bunch of lines to screen. These lines are to help you step through your code. At line 10 I left the numbers in the array that I used to eventually find the problem with your code. Try to see if you can use the output to step through your code and identify the problem (hint: its literally one line with the wrong variable used). When you are satisfied that the code works, set the boolean value to false and you can verify your code as is.

Henk

Level 19 , Pretoria, South-Africa

29 April 2019, 09:53

hi Guadalupe I like the debug info you shared. Problem is that the code editor we use doesn't execute the code when you click on the green arrow. It just runs through it, not asking for user input, or not even stopping after 10 iterations IF you enter user input in a loop (of 10 iterations). So not sure how to run it using IntellejIDEA is the main problem

Henk

Level 19 , Pretoria, South-Africa

29 April 2019, 11:32

Guadalupe, I used your debug code now, thank you, I am starting to become more adept using IntelliJIDEA

Godwin

Level 14 , Sango, Nigeria

23 May 2019, 18:57

GG, do you debug all the code you write?

Guadalupe Gagnon

Level 37 , Tampa, United States

23 May 2019, 19:18

Most of the code i write. I make small mistakes all the time in code, and the longer it gets the more mistakes there will be. It saves a LOT of time finding your mistakes as you go along rather than working for a couple of hours and making 1 small mistake in the beginning that screws up all your code. Finding that one mistake can take more time at that point than the time to just debug as you go along. Small projects I typically wont though.

Godwin

Level 14 , Sango, Nigeria

23 May 2019, 19:33

Okay, thanks to you I now know how to properly debug a code. I discovered a lot of mistakes that I am now trying to fix in a task I was stuck on for hours. I wish I knew how to debug earlier, it would have saved me a lot of time. Thank you once again, you are the best.