Practice with ArrayList

great exercises to solidify ArrayList concept !

hint: pueden ayudarse de indexof() hint: indexOf() is usefull

Can somebody please explain, why I get 6 as the highest number? BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); ArrayList<Integer> list = new ArrayList<Integer>(); for (int i = 0; i < 5; i++) { list.add(Integer.parseInt(reader.readLine())); } int highestNumber = list.get(0); System.out.println(list); for (int i = 0; i < list.size(); i++) { for (int j = i; j < list.size(); j++) { if (list.get(i) >= list.get(j)) { highestNumber = list.get(i); } else{ highestNumber = list.get(j); } } } System.out.println(highestNumber); } }

I think there is a bug in the exercise "The largest number" because the Requirements say first of all to read 5 numbers from the keyboard and write them to the integers list, which my program does and second of all to display the maximum number on the screen which my program also does and the maximum number gets shown in the output, so i don't get it. Why do i not pass the test? Or is it that the integers list cannot hold the primitive data type int, but only the object Integer, but if that were the case the maximum number would not get displayed in the output, and i would get an error, right? This is my code: package en.codegym.task.jdk13.task07.task0708; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.ArrayList; /* The largest number */ public class Solution { private static ArrayList<Integer> integers = new ArrayList<>(); public static void main(String[] args) throws Exception { //write your code here BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); int i = 0; while (i < 5) { integers.add(Integer.parseInt(reader.readLine())); i++; } int maximumNumber = 0; for (int item : integers) { if (item > maximumNumber) { maximumNumber = item; } } System.out.println(maximumNumber); } }

Here: https://codegym.cc/help/4942

package com.codegym.task.task07.task0708; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.List; /* Longest string */ public class Solution { private static List<String> strings; static int c_len = 0, o_len = 0; public static void main(String[] args) throws Exception { Solution.strings = new ArrayList<>(); ArrayList<String> lstr = new ArrayList<>(); for (int i = 0; i < 5; i++) { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); Solution.strings.add(br.readLine()); } for ( int i = 0; i < strings.size(); i++){ c_len = strings.get(i).length(); if ( c_len > o_len ){ o_len = c_len; for ( int j = lstr.size()-1; j >= 0; j--){ lstr.remove(j); } lstr.add(0,strings.get(i)); } else if(c_len == o_len){ lstr.add(strings.get(i)); } } for ( int j = 0; j < lstr.size(); j++){ System.out.println(lstr.get(j)); } } } This is working but validation failed

For "Longest String" there are definitely methods that will work but fail validation. For example, creating a second Arraylist to store only the strings that are tied for longest will fail validation, even if it works in testing for all numbers of tied strings. My guess is that the validator is expecting to find the variable "strings" in the System.out.

for (String s : longList) {
            System.out.println(s);
        }

Never give up my friends. Keep on pushing

(String str : list), someone can explain me what does " : " mean?

Expressing ourselves more concisely: What's wrong with this statement? The verifery tells me: List<String> myStrings = new ArrayList<String>(); "Declare a string list variable and immediately initialize it." Failed. I don't see the problem. The code runs correctly.