Insertion Sort. Cannot print sorted values

Question

I am new to java and we are task to make an insertion sort but I have a little problem with my codes I can't print my Sorted values I can't figure out where are my faults ...please help me. thank you

import java.util.Scanner;
public class Sorting {

public static void main(String[] args){
System.out.println("Enter 10 numbers to be sorted separated with spaces:");
String values = new Scanner(System.in).nextLine();
 String [] Vstring = values.split(" ");
 int [] num = new int[Vstring.length];

 for(int i = 0; i<num.length; i++){
    num[i]=Integer.parseInt(Vstring[i]);

     }

     }
     public static void insertionSort(int[] list, int n){
     for(int i = 0; i<n; i++)
      {
        int key = list[i];
        int j = i-1;
        while(j >=0 && list[j]>key){
            list[j+1] = list[j];
            j=j-1;
        }

        list[j+1] = key;
        }


        }

       public static void printValues(int [] list){
       for (int i = 0; i<list.length; i++){
           System.out.println(list[i]+"");
       }
      System.out.println();
     }
     }

score 0 · Answer 1 · edited May 23 '17 at 10:24

To start, you nested a function within main. I don't think you can do that. Please separate them (I'll show an example) and see if that helps you. Also, be careful with user input. Assume the user is going to make mistakes, and program defensively. What if I were to type "Hello" into this program? It would throw a hard exception and crash. Try to prevent this kind of thing.

Also, I don't know if arrays can be passed by reference or not in Java, so I've modified your sort method to return the new "sorted" array.

public static void main(String[] args){

System.out.println("Enter 10 numbers to be sorted separated with spaces:");

String values = new Scanner(System.in).nextLine();

 String [] Vstring = values.split(" ");
 int [] num = new int[Vstring.length];

 for(int i = 0; i< num.length; i++){
      num[i] = Integer.parseInt(Vstring[i]);
 }

 num = insertionSort(num, num.length);
 printValues(num);

}

 public static int[] insertionSort(int[] list, int n){
     for(int i = 0; i<n; i++)
      {
        int key = list[i];
        int j = i-1;
        while(j >=0 && list[j]>key){
            list[j+1] = list[j];
            j=j-1;
        }

        list[j+1] = key;
        }

      return list;

  }


  public static void printValues(int [] list){
       for (int i = 0; i<list.length; i++){
           System.out.println(list[i]+"");
       }

       System.out.println();

  }

Edited my mistake with Vstring not being num in the function calls. To whomever downvoted my answer, please see: http://meta.stackexchange.com/questions/135/encouraging-people-to-explain-downvotes — Ricky Mutschlechner, Jul 03 '14 at 16:30

user3717646 · Answer 2 · 2014-07-03T16:46:37.413

0

Try this code, You should call insertionSort(num, num.length) method and printValues(int[] list) inside main method. I modified the return type of insertionSort method as well.

public static void main(String[] args) {
    System.out.println("Enter 10 numbers to be sorted separated with spaces:");
    String values = new Scanner(System.in).nextLine();
    String[] Vstring = values.split(" ");
    int[] num = new int[Vstring.length];

    for (int i = 0; i < num.length; i++) {
        num[i] = Integer.parseInt(Vstring[i]);

    }

    int[] result=insertionSort(num, num.length);
    printValues(result);
}

public static int[] insertionSort(int[] list, int n) {
    for (int i = 0; i < n; i++) {
        int key = list[i];
        int j = i - 1;
        while (j >= 0 && list[j] > key) {
            list[j + 1] = list[j];
            j = j - 1;
        }

        list[j + 1] = key;
    }
    return list;
}

public static void printValues(int[] list) {
    for (int i = 0; i < list.length; i++) {
        System.out.println(list[i] + "");
    }
    System.out.println();
}

edited Jul 03 '14 at 16:46

answered Jul 03 '14 at 16:28

user3717646

436
3
10

I would say standard practice doesn't involve printing from within the insertionSort method. Looks fine otherwise. – Ricky Mutschlechner Jul 03 '14 at 16:29
@RickyMutschlechner , Is that good to use a static int [] list attribute and print using it? – user3717646 Jul 03 '14 at 16:38
I would just say that it'd be better to print from main. In terms of reusability, what if someone doesn't want to print every single time they sort? It'd be beneficial to have that as an option rather than as mandatory. – Ricky Mutschlechner Jul 03 '14 at 16:39
1

I made the edit, thank you for your kindness @RickyMutschlechner – user3717646 Jul 03 '14 at 16:47

score 0 · Answer 3 · answered Jul 03 '14 at 16:38

The problem is that you aren't calling your functions in main. Your code will compile, (although you might want to have some indents/spaces for readability... Ctrl+A then Ctrl+I will help somewhat) but you will not get any results.

Here is what you have to do:

import java.util.Scanner;
public class Sorting {

    public static void main(String[] args){

        System.out.println("Enter 10 numbers to be sorted separated with spaces:");
        String values = new Scanner(System.in).nextLine();
        String [] Vstring = values.split(" ");
        int [] num = new int[Vstring.length];

        for(int i = 0; i<num.length; i++){
            num[i]=Integer.parseInt(Vstring[i]);
        }

        //HERE!!!!! Call the functions!
        insertionSort(num, num.length); 
        printValues(num);

    }

    public static void insertionSort(int[] list, int n){
        for(int i = 0; i<n; i++)
        {
            int key = list[i];
            int j = i-1;
            while(j >=0 && list[j]>key){
                list[j+1] = list[j];
                j=j-1;
            }

            list[j+1] = key;
        }
    }

    public static void printValues(int [] list){

        for (int i = 0; i<list.length; i++){
            System.out.println(list[i]+"");
        }
        System.out.println();
    }
}

I hope it helped! :)

score -1 · Answer 4 · edited Jul 03 '14 at 20:04

-1

You do not call the printValues function. You also do not call the sorting function. The code inside a function is only executed once you call it. Also I would suggest indenting the code so that things inside two braces are indented twice etc.

edited Jul 03 '14 at 20:04

BenMorel

34,448
50
182
322

answered Jul 03 '14 at 16:28

Joonazan

1,408
10
18

This code doesn't even compile most likely let alone run properly. – Ricky Mutschlechner Jul 03 '14 at 16:29

Insertion Sort. Cannot print sorted values

4 Answers4