How can I see the "System.out.println()" output in IntelliJ IDEA ?

Question about the task

Task about algorithms

Java Syntax, Level 8, Lesson 11

Resolved

It only shows that it ran the program successfully with return code 0.

package com.codegym.task.task08.task0830; import java.io.BufferedReader; import java.io.InputStreamReader; /* Task about algorithms */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); String[] array = new String[20]; for (int i = 0; i < array.length; i++) { array[i] = reader.readLine(); } sort(array); for (String x : array) { System.out.println(x); } } public static void sort(String[] array) { String[] array2 = array; String stringFirst = "ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ"; int i = 0, j = 0,k=0; for (j=0;j< array.length;j++){ for (i = 0; i < array.length; i++) { if (isGreaterThan(stringFirst, array[i])) { stringFirst = array[i]; } } array2[k] = stringFirst; k++; } array = array2; } // String comparison method: 'a' is greater than 'b' public static boolean isGreaterThan(String a, String b) { return a.compareTo(b) > 0; } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

13 March 2020, 14:22

You do have a problem in your code with aliasing (https://en.wikipedia.org/wiki/Aliasing_(computing)). Take this bit of code for example:

public static void main(String[] args) throws Exception {
   // create 2 string arrays, set values of second one to the
   // values of the first one
   String[] ar1 = {"ar1 1", "ar1 2", "ar1 3"};
   String[] ar2 = ar1;

   // output the values to make sure they are the same
   System.out.println("Testing values are the same:");
   System.out.println("ar1: " + Arrays.toString(ar1));
   System.out.println("ar2: " + Arrays.toString(ar2));
   System.out.println();

   // in ar2: changes the "ar1" part of each string to "ar2"
   System.out.println("Changing all values in ar2 to reflect ar2");
   for(int i = 0; i < ar2.length; i++)
      ar2[i] = ar2[i].replace("ar1", "ar2");

   // checks that values have been changed
   System.out.println("Testing ar2: " + Arrays.asList(ar2));
   System.out.println();

   // outputs both arrays again.
   System.out.println("Testing values both arrays:");
   System.out.println("ar1: " + Arrays.toString(ar1));
   System.out.println("ar2: " + Arrays.toString(ar2));
}

If you run it and check, at the very end of the code both arrays have identical outputs, even though lines 15 and 16 changed the values in the second array. This is because line 5 does not copy the values into a new array, but instead say that the variable "ar2" should direct to the same array that "ar1" stores. Now they both are connected to the same exact array in memory. This is what your code above does on line 27.

Johannes

Level 27 , Centurion, Pretoria, South-Africa

13 March 2020, 16:33

So is the only way to copy array to array2, to do it in a "for" loop ? Thanks ;)

Johannes

Level 27 , Centurion, Pretoria, South-Africa

13 March 2020, 16:34

What do I do to get around the sorting problem of capital alpha's that are placed in different areas in the sort order than lower-case alpha's ?

Guadalupe Gagnon

Level 37 , Tampa, United States

13 March 2020, 17:00

In this task you don't need to worry about lowercase and uppercase, just use the strings by the isGreaterThan() result. Copying using a loop is one way of doing it, and may be easiest for new comers, though the Arrays class also provides static methods that can create a copy of an array: statics: Arrays.copyOf() - this copies from index 0 to the specified length Arrays.copyOfRange() - this copies from the start point to an end point (won't include the end point)

Guadalupe Gagnon

Level 37 , Tampa, United States

13 March 2020, 14:17

It should be at the bottom of the screen. There may be tabs, click the solution tab. You may need to google where to show the output window if you still can't find it: .