Sorting 10 Double Arrays

[Kris French]

Hello Everybody,

I'm trying to sort 10 inputted numbers (double precision) using the Array.sort() method. I'm actually kind of proud that I made it this far on my own, but I have ran into a wall.

I can get the 10 numbers inputted, but the output is ten 0.0s; now (and this how I know I am learning some things) I'm fairly certain that the variable number is not storing the numbers inputted by the user otherwise I wild be seeing the program work correctly.

So my question is why isn't number storing the inputs?

import javax.swing.JOptionPane;
import java.util.Arrays;

public class KrisFrench3 {
    public static void main(String[] args) {
        double[] number = new double[10];               
                
        for(int i = 1; i <= i; i++) {
            JOptionPane.showInputDialog("Enter 10 numbers: " 
                    + "Number:" + i);           
            
        }        
                
        Arrays.sort(number);
        for(int i = 0; i < number.length; i++){
            System.out.println(number[i]);
        }
        
    
    }
     
}

As always, thank you for the help.

Kris

[J. Kevin Robbins]

You are prompting the user for numbers, but where are you adding them to the array? Adding values to an array is convoluted. I suggest you use a Collection such as an ArrayList which has an .add() method for putting those values in the collection. It's much simpler.

[Joanne Neal]

Kris French wrote:I can get the 10 numbers inputted, but the output is ten 0.0s;

You should always post the code you are using. The code you posted won't output anything because you have an infinite loop* at line 8.

*Or possibly a very long running loop - it may end when i reaches Integer.MAXVALUE and is then incremented.

[Campbell Ritchie]

Infinite.

[Kris French]

Oops...thank you Joanne. There were a few changes made when I was researching how to accomplish this. I do have to use the Array.sort() method.

Here is where I was when I thought I was on the right track:

import javax.swing.JOptionPane;
import java.util.Arrays;

public class KrisFrench3 {
    public static void main(String[] args) {
        double[] number = new double[10];               
                
        for(int i = 1; i <= 10; i++) {
            Double.parseDouble(JOptionPane.showInputDialog("Enter 10 numbers: " 
                    + "Number:" + i));           
            
        }        
                
        Arrays.sort(number);
        for(int i = 0; i < number.length; i++){
            System.out.println(number[i]);
        }
        
    
    }
     
}

[fred rosenberger]

your lines 9 and 10 ask the user to input a number...but you still are not doing anything with it. You have to tell java exactly where you want to save it, else it basically gets thrown away.

[Campbell Ritchie]

And how are you filling the array? If you don't put values into the array, it will contain ten copies of 0.0.

Don't write 10 twice. Second time round you want to use the length of the array. So write numbers.length. Call the array numbers rather than number.
Why are you using JOptionPane for keyboard input? It is very old‑fashioned practice.
Use a for‑each loop to display the array. Or if you have to use the Arrays class, it has a method for converting an array to a String. You might as well use that.

[Partheban Udayakumar]

Kris French

Kindly review your code

for(int i = 1; i <= 10; i++) {  
            Double.parseDouble(JOptionPane.showInputDialog("Enter 10 numbers: "   
                    + "Number:" + i));             
              
        }  

In the above for loop you are just parsing the number to a double. You should store it in the array and as sheriff says try using for each loop for displaying the contents. If you are sure that only 10 elements will be present use arrays else go for the flexible arraylist

[Kris French]

Thank you all for your help. I knew nothing was getting stored in the array, but I just needed to figure out why. After some digging, it looked like using the Scanner was the way to go. I imported the Scanner utility and added the appropriate line of code to the program, but then I kept getting array.index.outofbounds exception. I did some reading on why this happens and it turned out that in the first loop, I was using

i <= numbers.length;

and when I switched to

i < numbers.length;

the program worked as it was intended.

Now my next challenge is to get the Number to count. for example; "Enter 10 numbers" then the program will print Number 1, Number 2, etc. Anyway, here is the program. Again thank you:

package krisfrenchhw3;

import java.util.Scanner;
import java.util.Arrays;

public class KrisFrenchHw3 {
    public static void main(String[] args) {
        double[] numbers = new double[10];               
        Scanner input = new Scanner(System.in); 
        
        System.out.println("Enter 10 numbers:");
        
        for(int i = 0; i < numbers.length; i++) {           
            System.out.println("Number: " + i);           
            numbers[i] = input.nextDouble();
        }  
        
        System.out.println("Here is the list of numbers from smallest to largest");                
                
        Arrays.sort(numbers);
        for(int i = 0; i < numbers.length; i++){
            System.out.println(numbers[i]);
        }       
    
    }
     
}

Kris

[Campbell Ritchie]

Well done working out the <= bit

I don't like <= and >=. They are not wrong, but < and > are much easier to understand, so try to use < and > whenever possible. There is a customary form for a for loop to traverse an array:-

for (int i = 0; i < myArray.length; i++)
{
   myArray[i] = ...;
}

Use that form as a basis for all for loops with arrays. That always works and never throws an out of bounds Exception. For traversing an array where it is not necessary to reassign the elements, always use a for‑each loop, officially called an “enhanced for statement”.

[aster tersa]

public class Bublesorti {

    public static void main(String[] args) {

        int[] t = {23, 45, -500, 1000, 12};
        for (int i = 0; i < t.length; i++) {
            for (int j = i + 1; j < t.length; j++) {
                if (t[i] > t[j]) {                    swap(t, i, j);                }
            }
        }
        
for (int i = 0; i < t.length; i++) {            System.out.println(t[i]);        }
    
}

    private static void swap(int[] h, int k, int d) {
        if (k == d) {            return;        }
        int temp = h[k];
        h[k] = h[d];
        h[d] = temp;
    }

}

[Campbell Ritchie]

Welcome to the Ranch

[Campbell Ritchie]

Please indent the code correctly. Having { and } on the same line makes code very difficult to read, even more so with all those spaces.
Don't use return. Much simpler to have the swap method like this

public static void swap(int[] array, int i, int j)
{
   if (i != j) // Use != rather than ==
   {
      int temp = array[i];
      array[i] = array[j];
      array[j] = temp;
   }
}

[Liutauras Vilda]

public static void swap(int[] array, int i, int j)

Parameters "int i, int j" are not necessary, otherwise I missed something.

[Campbell Ritchie]

Yes, i and j are necessary. They represent the two indices to swap.

[Liutauras Vilda]

Sure, didn't check full code.
Please omit my previous post.