Why version 1 is good but second no :D ? - java help on CodeGym

I have problem with 3 i 5 points with version 2 Version 1 package pl.codegym.task.task04.task0428; /* Liczba dodatnia */ import java.io.*; import java.util.ArrayList; public class Solution { public static void main(String[] args) throws Exception { //tutaj wpisz swój kod BufferedReader r = new BufferedReader(new InputStreamReader(System.in)); int a = Integer.parseInt(r.readLine()), b = Integer.parseInt(r.readLine()), c = Integer.parseInt(r.readLine()); ArrayList<Integer> lista = new ArrayList<Integer>(); lista.add(a); lista.add(b); lista.add(c); int count=0; for(int i = 0; i < lista.size(); i++) { if(lista.get(i) > 0 ) { count++; } } System.out.println(count); } } Version 2 package pl.codegym.task.task04.task0428; /* Liczba dodatnia */ import java.io.*; import java.util.ArrayList; public class Solution { public static void main(String[] args) throws Exception { //tutaj wpisz swój kod BufferedReader r = new BufferedReader(new InputStreamReader(System.in)); int a = Integer.parseInt(r.readLine()), b = Integer.parseInt(r.readLine()), c = Integer.parseInt(r.readLine()); ArrayList<Integer> lista = new ArrayList<Integer>(); lista.add(a); lista.add(b); lista.add(c); int count=0; for(int i = 0; i < lista.size(); i++) { if(lista.get(i) > 0 ) { count=+1; } } System.out.println(count); } }

// you need to be aware of the problems int i = 5; // i = i + 1L; compilation error, incompatible types i += 1L; // no problem but can lead to problems if lossy conversation kicks in like; i = 2147483647; i += 1L; // int overflow System.out.println(i); // -2147483648 // but this also can be very convenient char c = 'a'; // c = c + 1; // same as above, does not compile, incompatible types c += 1; // so it's synonym to c = (char) (c + 1) System.out.println(c); // b

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Dawid

Poziom 13 , Poland

Expert

1 maja 2023, 10:19

Thank you.

Thomas

Poziom 41 , Bayreuth, Germany

28 kwietnia 2023, 12:21

rozwiązanie

you confused += and =+ eg.

count=+1;

is synonym to

count = 1;

in each iteration you assign 1 to count on the other hand

count++;

count += 1;

count = count + 1;

3 maja 2023, 13:46

To be absolutely precise, i += i is not really synonym to i = i + 1 it's synonym to i = (T) (i + 1), where T is the type of the variable you assign the result. Two examples showing the problems and the benefits. This may not be very interesting at this point of learning, though ;)