Challenge 2 - NumberRange

Index

In this challenge we're to follow up our SmartyNumber work and code a class that models a number range.

NOTE WELL -- Java has multiple types of primitive integers -- for NumberRange all ivars, numeric return data types, and numeric parameters will be type long, unless otherwise noted

Instructions

Read through the challenge general rules and tips
Code the class defined on this page
It is suggested (but not required) to add a test class -- always a good idea
Have a ball! (fun)

Class

Add a class named NumberRange.

Instance Variables

Add two private instance variables named "start" and "stop" (both of type long).

These numbers will be used by NumberRange's methods that do logic and calcs (below).

Constructors

These two methods are NumberRange's most important methods. The reason why is that object users will use these methods to construct SmartNumber objects -- we must be able to construct objects first to use them.

Standard Constructor

NumberRange has one standard constructor which has two parameters of type 'long'.

The first parameter should set the ivar "start" and the second parameter should set the ivar "stop".

Static Factory Constructor

NumberRange also has one static factory constructor.

It can be coded as shown here (copy-paste) -- you will learn details about these methods in advanced programming.

/** static factory constructor */
public static NumberRange fromStartStop(long start, long stop) {
	return new NumberRange(start, stop);
}

Range Rules and Assumptions

The start and stop are included in the range. E.g. if we have a range from start=10 and stop=12 the numbers in the range would be 10, 11 and 12.

You may assume the first param (passed to the constructor) will be greater than zero, and assume the second param (passed to the constructor) will be equal or greater than the first.

Instance Method Definitions (Explained)

Each Method Definition provides a definition of an instance methods that to be added (coded) to NumberRange.

Instance Method Definition (Explained)

An example method definition is shown here:

size

Returns the size (a long) of the range

Examples:

start=10 stop=12 then size=3
The size is 3 because the range includes:
10, 11 and 12

start=20 stop=20 then size=1
The size is 1 because the range includes:
20

Notes Pertaining to the Method Definition Above:

The method name is size
Below the method name is a description of the method
Return types and method param types can be derived from the method description
If no method params are mentioned, that means there are no method params for the given method
If no return value is specified then the method does not return a value (i.e., the return type is coded as void)
When a method description uses terminology such as "our number", "this number", "the number", etc it is talking about the num in the particular instance of the brainy or smart number
To the right is additional information such as examples of method usage, example test values, etc

Instance Method Definitions - Core

toString

This is the standard "toString" method. We add to help with debugging.

We can code it just like shown here.

public String toString() {
	return String.format("[%d, %d]", this.getStart(), this.getStop());
}

getStart

Returns the ivar named start

//Example Usage
NumberRange range = new NumberRange(10, 20);
println('Start: ' + range.getStart());
//Start: 10

getStop

Returns the ivar named stop

//Example Usage
NumberRange range = new NumberRange(10, 20);
println('Stop ' + range.getStop());
//Stop: 10

setStart

Sets the ivar named start with the passed parameter.

Receives one parameter, of data type long.

//Example Usage
NumberRange range = new NumberRange(10, 20);
println('Start: ' + range.getStart());
//Start: 10
range.setStart(1000);
println('Start: ' + range.getStart());
//Start: 1000

setStop

Sets the ivar named stop with the passed parameter.

Receives one parameter, of data type long.

//Example Usage
NumberRange range = new NumberRange(10, 20);
println('Stop: ' + range.getStop());
//Stop: 10
range.setStop(5000);
println('Stop: ' + range.getStop());
//Stop: 5000

size

Returns the size (an long) of the range

Examples:

start=10 stop=12 then size=3
The size is 3 because the range includes:
10, 11 and 12

start=20 stop=20 then size=1
The size is 1 because the range includes:
20

includes

Returns true if our range includes the method parameter (which is type long).

Recall that our range includes the start and stop values.

intersection

Returns a new NumberRange object that is the intersection between this range and the parameter (which is another NumberRange).

For example if our range is 1-100, and the parameter's range is 91-200, then we would return a new NumberRange with a range of 91-100.

If there is no intersection, return a range with start and stop both equal to 0.

These Java methods may be handy to use:

Math.max(a, b); //returns max of a and b
Math.min(a, b); //returns min of a and b

Instance Method Definitions - Counts

evenCount

Returns the count of even numbers in our range.

For a range from 0 to 100, then we would expect evenCount to be 51

oddCount

Returns the count of odd numbers in our range.

For a range from 0 to 100, then we would expect oddCount to be 50

countPrimes

Returns the count of prime numbers in our range.

Several example counts are shown.

Examples:
Start	Stop	Primes Count
1	10	4
1	100	25
1	1000	168

countDivisibleBy

This method takes three parameters: (long factor1, long factor2, boolean mustBeBoth)

The param mustBeBoth drives the method logic like this:

mustBeBoth	Description
true	Return count of nums in our range that are divisible by both factor1 AND factor2
false	Return count of nums in our range that are divisible by both factor1 OR factor2

Examples:

Range Start	Range Stop	factor1	factor2	mustBeBoth	countDivisibleBy (Resulting Count)
1	10	2	5	true	1
1	10	2	5	false	6
1	1000	2	5	true	100
1	1000	2	5	false	600

countFactorJKZs

Returns a count of the numbers in our range that have a factorJKZ greater or equal to the parameter value passed into this method (the threshold/minimum).

Receives one method parameter that is a long type indicating the threshold (minimum) that will dictate if we include a number in the count.

The definition of factorJKZ can be found in SmartNumber.

countFactorRatios

Returns a count of the numbers in our range that have a factorRatio greater or equal to the parameter value passed into this method (the threshold/minimum).

Receives one method parameter that is a long type indicating the threshold (minimum) that will dictate if we include a number in the count.

The definition of factorRatio can be found in SmartNumber.

countPalindromes

Returns a count of the numbers in our range that are palindromes.

The definition of isPalindrome can be found in SmartNumber.

countSquareAndCubeNumbers

Returns a count of the numbers in our range that both a square and a cube.

More information on square and cube numbers can be found in SmartNumber.

Instance Method Definitions - Other

sumPrimes

Returns the sum of prime numbers in our range.

Several example counts are shown.

Range Start	Range Stop	Primes Sum
1	10	17
1	100	1,060
1	1000	76,127

largestPrimeGap

This method receives no params and returns the size (count) of the largest consecutive "gap" of non-primes in our range that are between two prime numbers (that also must be in our range).

For example, given the range 1 to 10, the largest non-prime consecutive gap is:

4
(count = 1)

Note that we do NOT count the non-primes 8, 9 and 10 (length 3) because they are not bound, on the right side, by a prime number (that must be in our range).

Another example is given the range 10 to 20, the largest non-prime consecutive gap is:

14, 15, 16
(count = 3)

Several example counts are shown.

Example Results:

Start	Stop	Largest Prime Gap
3	3	0
4	4	0
1	10	1
10	20	3
1	1000	19
10,000	11,000	31
100,000	101,000	53

largestPrimeGapPair

Returns a string for the largest prime gap. Also see method description for largestPrimeGap. The string is:

prime1 + "-" + prime2

There are no spaces in the string.

For example if our range is 10-20, then the primes are 11, 13, 17, and 19. So the largest gap between any two primes in our range is between 13 and 17. So we would return:

“13-17”

If our range does not have any gap (i.e., zero or one primes), then return a string "0-0".

if our range has multiple gaps with the "largest prime gap" return the first.

Start	Stop	Largest Prime Gap Pair
1	10	3-5
1	20	7-11
10	20	13-17

shrink

No return value.

Receives one parameter of type long which is a factor to use to shrink our range.

Shrink the range size (length) by the passed in factor (compute a new length using the factor)
Preserve our start position
Adjust the stop position to accommodate the newly computed length

Example:

Given a passed in parameter shrink factor of 3
Take our length and divide it by 3 to compute new length (round result)

sumFactorJKZs

Returns a sum of the factorJKZs for the numbers in our range.

The definition of factorJKZ can be found in SmartNumber.

getSummary

Return a summary string of the NumberRange
Show one property per line
The example here shows four properties
You may use this example method as-is except add at least five more properties so that nine or more properties are displayed

public String getSummary() {
	String summary = "";
	String sep = System.lineSeparator();
	summary += "Start: " + this.getStart() + sep;
	summary += "Stop: " + this.getStop() + sep;
	summary += "Prime Count: " + this.countPrimes() + sep;
	summary += "Odd Count: " + this.oddCount() + sep;
	//TODO
	return summary;
	}

Grading

For this assignment, we will use these grading rules.

Introduction To Objects With Java (Chapter 603 - Loops)

Chapter 603 - Loops Challenge 2 - NumberRange

Contents Overview Concepts While With Objects With Helpers For Examples Challenges

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