# Arrays

Usually we use an array because we want to access the array in a different order.

The program below reads in three numbers, sorts them, then prints them.

 `12345678910111213141516171819202122232425` ```//Arrays: Read 3 numbers, sort and print package numbers; import java.util.*; public class Numbers { public static void main(String[] args) { Scanner keyboard=new Scanner(System.in); double[] num= new double[3]; for(int i=0;i<3;i++){ System.out.print("Enter a number:"); num[i]=keyboard.nextDouble(); }//for loop to input if (num[0] > num[1]) swap(num,0,1); if (num[1] > num[2]) swap(num,1,2); if (num[0] > num[1]) swap(num,0,1); for(int i=0;i<3;i++){ System.out.println(num[i]); }//for loop to output }//main public static void swap(double d[],int i, int j){ //swap elements i and j double temp=d[i]; d[i]=d[j]; d[j]=temp; }//swap }//class```
CODE

It is important to note that Java always passes primitive variables by value. Objects and arrays are passed a reference to the address.

In this program the reference to the array is passed to swap, but the values 0 and 1 are passed.

This algorithm works for just 3 numbers. You will study other algorithms for sorting large arrays.