Java Operating on a Series of Integers - Web Development and Design | Tutorial for Java, PHP, HTML, Javascript Java Operating on a Series of Integers - Web Development and Design | Tutorial for Java, PHP, HTML, Javascript

Wednesday, January 2, 2019

Java Operating on a Series of Integers

Problem

You need to work on a range of integers.

Solution

For a contiguous set, use a for loop.

Explained

To process a contiguous set of integers, Java provides a for loop. * Loop control for
the for loop is in three parts: initialize, test, and change. If the test part is initially
false, the loop will never be executed, not even once.

For discontinuous ranges of numbers, use a java.util.BitSet .

The following program demonstrates all of these techniques:

import java.util.BitSet;
/** Operations on series of numbers */
public class NumSeries {
public static void main(String[] args) {

// When you want an ordinal list of numbers, use a for loop
// starting at 1.
for (int i = 1; i <= months.length; i++)
System.out.println("Month # " + i);
// When you want a set of array indexes, use a for loop
// starting at 0.
for (int i = 0; i < months.length; i++)
System.out.println("Month " + months[i]);
// For a discontiguous set of integers, try a BitSet
// Create a BitSet and turn on a couple of bits.
BitSet b = new BitSet( );
b.set(0);
// January
b.set(3);
// April
// Presumably this would be somewhere else in the code.
for (int i = 0; i<months.length; i++) {
if (b.get(i))
System.out.println("Month " + months[i] + " requested");
}
}
/** The names of the months. See Dates/Times chapter for a better way */
protected static String months[] = {
"January", "February", "March", "April",
"May", "June", "July", "August",
"September", "October", "November", "December"
};
}