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 ca

Answer 1

If you want to use any external library here is Apache commons math library using you can calculate the Median.
For more methods and use take look at the API documentation

import org.apache.commons.math3.*;
.....
......
........
//calculate median
public double getMedian(double[] values){
 Median median = new Median();
 double medianValue = median.evaluate(values);
 return medianValue;
}
.......

• For more on evaluate method AbstractUnivariateStatistic#evaluate

Update

Calculate in program

Generally, median is calculated using the following two formulas given here

If n is odd then Median (M) = value of ((n + 1)/2)th item term.
If n is even then Median (M) = value of [((n)/2)th item term + ((n)/2 + 1)th item term ]/2

In your program you have numArray, first you need to sort array using Arrays#sort

Arrays.sort(numArray);
int middle = numArray.length/2;
int medianValue = 0; //declare variable 
if (numArray.length%2 == 1) 
    medianValue = numArray[middle];
else
   medianValue = (numArray[middle-1] + numArray[middle]) / 2;