tried many things

Question about the task

Playing Javarella

Java Syntax, Level 7, Lesson 9

Resolved

Cab someone help me explain why this is not working at all?

1. Enter 20 numbers from the keyboard, save them in a list, and then sort them to three other lists:
Numbers divisible by 3 (x%3==0), numbers divisible by 2 (x%2==0), and all other numbers.
Numbers simultaneously divisible by 3 and 2 (for example 6) go into both lists.
The order in which the lists are declared is very important.
2. The printList method should display each list item on a new line.
3. Using the printList method, display these three lists. First, the list for x%3, then the list for x%2, and then the last list.

Requirements:

Declare and immediately initialize 4 ArrayList<Integer> variables. The first list will be the main one. The other lists will be supplementary.
Read 20 numbers from the keyboard and add them to the main list.
Add to the first supplementary list all numbers in the main list that are divisible by 3.
Add to the second supplementary list all numbers in the main list that are divisible by 2.
Add to the third supplementary list all the remaining numbers from the main list.
The printList method should display each element of the passed list on a new line.
The program should display the three supplementary lists using the printList method.

package com.codegym.task.task07.task0713; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.List; /* Playing Javarella */ public class Solution { public static void main(String[] args) throws Exception { //write your code here BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); ArrayList<Integer> originalList = new ArrayList<Integer>(); ArrayList<Integer> numDiv3 = new ArrayList<Integer>(); ArrayList<Integer> numDiv2 = new ArrayList<Integer>(); ArrayList<Integer> numRest = new ArrayList<Integer>(); for(int i = 0; i < 20; i++){// enter 20 number from keyboard and aad them to the originalList int c = Integer.parseInt(reader.readLine()); originalList.add(c); } for (Integer c : originalList){//loops over the originalList if(c %3 == 0) // if the number is divisible by 3 { numDiv3.add(c);// it will be added to the numDiv3 list } if(c %2 == 0) // if the number is divisble by 2 { numDiv2.add(c); // it will be added to the numDiv2 list } if((c %3 == 0) && (c % 2 == 0)) // if the number is divived by 3 and 2 such as 6 { numDiv3.add(c); //the number will be added to numDiv3 numDiv2.add(c);// and the number will be added to numDiv2 } else { numRest.add(c);// all the remaining number will be added to the numrest list } } printList(numDiv3); printList(numDiv2); printList(numRest); } public static void printList(List<Integer> list) { //write your code here for (Integer c : list) {//loops over de original list System.out.println(c); } } }

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Liliane Top

Level 17 , Amsterdam, Netherlands

13 February 2020, 10:11

Anthony you're my hero today!

Anthony Chalk

Level 30 , London, United Kingdom

13 February 2020, 10:02

Because you're not using if-else for the first two conditions, the other conditions are checked irrespective of whether the first one has been fulfilled. Let's break it down: 1) Line 29, checks if the number is divisible by 3. If yes, adds it to the appropriate list and whether it is or isn't, moves on to the next condition 2) Line 33, checks if the number is divisible by 2. By this point, all the numbers that are divisible by 2 and/or 3 have been added to the correct list (including the ones that are divisible by both) 3) Line 37, checks if the number is divisible by both 2 and 3 and then adds to the correct list. Except, as line 29 and 33 were not using if-else, that's already been done, so you're adding duplicates to the lists 4) Line 42, if the number is not divisible by BOTH 2 and 3 add to numRest. This will include numbers that are divisible by ONLY 2 or 3. Remove lines 37-41 Change line 42 to: if (c %3 != 0 && c%2 !=0)