CodeGym/Help with Java Tasks/How print array

Livello 10

07.10.2022
697viste
12commenti

How print array

Domanda sul compito

Risolta

In this exercise requirement don't met even if the print is right i guess there is something wrong in the array printing. Can someone explain to me? Thanks so much

package com.codegym.task.task04.task0420; /* Sorting three numbers */ import java.io.*; import java.util.*; import java.util.Arrays; import java.util.Collections; public class Solution { public static void main(String[] args) throws Exception { //write your code here Scanner s = new Scanner(System.in); int n1 = s.nextInt(); int n2 = s.nextInt(); int n3 = s.nextInt(); Integer [] ar = {n1, n2, n3}; System.out.println(); Arrays.sort(ar, Collections.reverseOrder()); //for (int num : ar) { //System.out.print(num + " "); System.out.println(Arrays.toString(ar)); } }

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Thomas

Livello 41 , Bayreuth, Germany

7 ottobre 2022, 14:17

you're supposed to print three numbers separated by spaces like: 4 2 1 However the code above outputs numbers separated by commas and surrounded by brackets like: [4, 2, 1]

EvelynSt

Livello 10 , Italy

8 ottobre 2022, 14:05

Even with the for is wrong i guess because it end with a space? for (int num : ar) { System.out.print(num + " "); // 4 2 1 output System.out.println(Arrays.toString(ar)); // [4, 2, 1 output

Thomas

Livello 41 , Bayreuth, Germany

8 ottobre 2022, 16:33

yep... try to remove the trailing white space... there are numerous ways to do that

Integer[] arr = {2, 5, 7};
// #0
System.out.format("%s %s %s%n", arr[0], arr[1], arr[2]);

// #1
System.out.print(arr[0]);
for (int i = 1; i < arr.length; i++) {
    System.out.print(" " + arr[i]);
}
System.out.println();

// #2
StringBuilder sb = new StringBuilder();
for (int i : arr) {
    sb.append(i).append(" ");
}
System.out.println(sb.toString().trim());

// #3
System.out.println(Arrays.stream(arr).map(Object::toString).collect(Collectors.joining(" ")));

// #4
String[] strings = new String[arr.length];
for (int i = 0; i < arr.length; i++) {
    strings[i] = String.valueOf(arr[i]);
}
System.out.println(String.join(" ", strings));

// ... lots of other possibilities

EvelynSt

Livello 10 , Italy

8 ottobre 2022, 18:20

O m g i didn't know any of that. I need to save your message you are simply incredible, really thank you!!!!!!!

EvelynSt

Livello 10 , Italy

9 ottobre 2022, 01:54

I have tried them all keep failing 3 point.... no clue why

Thomas

Livello 41 , Bayreuth, Germany

9 ottobre 2022, 07:25

ups, haven't seen that you have additional output in your code that isn't asked by Codegym. That may be the problem (line 22). Btw. that approach using min/ max you posted in your other thread is one of my favorites at that point. You also could try a little sort algorithm for three variables (not the sort methods that are build into Java). if a < b -> swap if b < c -> swap now there's a possibility that a < b again so: if a < b -> swap output a b c

EvelynSt

Livello 10 , Italy

9 ottobre 2022, 10:06

You are a genius it was that line the problem! Nowi pass. With 12 try! I am really glad for your help. What do you mean with swap?

Thomas

Livello 41 , Bayreuth, Germany

9 ottobre 2022, 10:33

utile

you swap the values of the variables... eg. for a and b:

int temp = a;
a = b;
b = temp;

EvelynSt

Livello 10 , Italy

9 ottobre 2022, 11:26

I never see or use something like that! Is really interesting even if now I don't understand the purpose. I need to study more

Thomas

Livello 41 , Bayreuth, Germany

9 ottobre 2022, 13:46

Once you think about it, it's really simple. You have your three numbers 1 2 3 a b c and want to sort them desc 1. step, compare a, b, if a < b swap the values 2. step, that's the values after swapping a, b 2 1 3 a b c 3. step compare b, c, if b < c swap the values 4. step, that's the values after swapping b, c 2 3 1 a b c 5. step, compare a, b again, if a < b swap the value 6. step, that's the values after swapping 3 2 1 a b c a b c basically that's your first bubble sort algorithm

Thomas

Livello 41 , Bayreuth, Germany

9 ottobre 2022, 13:46

utile

Scanner console = new Scanner(System.in);
int a = console.nextInt();
int b = console.nextInt();
int c = console.nextInt();

if (a < b) {
    int temp = a;
    a = b;
    b = temp;
}
if (b < c) {
    int temp = b;
    b = c;
    c = temp;
}
if (a < b) {
    int temp = a;
    a = b;
    b = temp;
}
System.out.format("%d %d %d%n", a, b, c);

EvelynSt

Livello 10 , Italy

12 ottobre 2022, 04:33

Really thank you!!! If i have chance i will try to apply that.