How to calculate the median of an array?

Question

I'm trying to calculate the total, mean and median of an array thats populated by input received by a textfield. I've managed to work out the total and the mean, I just can't get the median to work. I think the array needs to be sorted before I can do this, but I'm not sure how to do this. Is this the problem, or is there another one that I didn't find? Here is my code:

import java.applet.Applet; import java.awt.Graphics; import java.awt.*; import java.awt.event.*;  public class whileloopq extends Applet implements ActionListener {     Label label;     TextField input;     int num;     int index;     int[] numArray = new int[20];     int sum;     int total;     double avg;     int median;        public void init ()     {         label = new Label("Enter numbers");         input = new TextField(5);         add(label);         add(input);         input.addActionListener(this);         index = 0;     }      public void actionPerformed (ActionEvent ev)     {         int num = Integer.parseInt(input.getText());         numArray[index] = num;         index++;         if (index == 20)         input.setEnabled(false);             input.setText("");         sum = 0;         for (int i = 0; i < numArray.length; i++)         {             sum += numArray[i];         }         total = sum;         avg = total / index;          median = numArray[numArray.length/2];            repaint();      }        public void paint (Graphics graf)     {            graf.drawString("Total   = " + Integer.toString(total), 25, 85);         graf.drawString("Average = " + Double.toString(avg), 25, 100);         graf.drawString("Median = " + Integer.toString(median), 25, 115);        } } 

Answer 1

The Arrays class in Java has a static sort function, which you can invoke with Arrays.sort(numArray).

Arrays.sort(numArray); double median; if (numArray.length % 2 == 0)     median = ((double)numArray[numArray.length/2] + (double)numArray[numArray.length/2 - 1])/2; else     median = (double) numArray[numArray.length/2];