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Assignment 10 - Pseudo Polygons




Assignment 10 - Pseudo Polygons;This extra credit assignment is worth 12 points. Don't worry about the fact that it may say ".1;points possible". You can get up to 12 points for it.;OPTION A (The Only Option): A List of Points;In elementary mathematics of 2-dimensions, each point on the plane (or paper or screen, if you like);can be represented by a pair of numbers, (x, y), where x tells you the horizontal location of the;point and y tells you the vertical location. The values are relative to some "origin" (0,0). So (3.1;0) is the point 3.1 units to the right of the origin, and (-3.6, 5) is the point 3.6 units to the leftof;the origin and 5 units above it. This allows us to label every point in the plane with a;unique (x,y) coordinate pair. The two numbers, x and y, are called the coordinates of the point.;Create a class called Point that has the following private members;float x - the x-coordinate of the point.;float y - the y-coordinate of the point.;Point should also contain;private static float MIN_VAL and MAX_VAL - which are initialized to -10.0 and +10.0;respectively. These will represent the legal range of both the x and y coordinates for;all Points in the class. It is important that these be static values since all objects will share;the same range limits.;If you wish, you can let x and y (and the two statics) be doubles. If you do, adjust the data types;of corresponding members below to be compatible with your choice.;Supply the following instance members;Two Constructors;one that takes no arguments which constructs a default point of (A, A), where A =;(MIN_VAL + MAX_VAL) / 2 (which would be (0,0) if MIN_VAL = -MAX_VAL);and another that takes two arguments, x and y which constructs a point (x, y).;boolean set(float x, float y) - a mutator which sets the coordinates of the point to x and y.;float getX() and float getY(), accessors for the x and y coordinates of the Point.;displayPoint() - displays the Point in the form "(0.46, -0.102);Also create a public static method;boolean setRange(float newMinVal, float newMaxVal) - a static method that changes;the floats MIN_VAL andMAX_VAL to the values passed (if successful). This method must;check that newMinVal < newMaxVal and return true orfalse, accordingly. Note that any;changes made to MIN_VAL and MAX_VAL through this method will not enforce the range of;any previously constructed Points, but will only affect future constructor and mutator calls.;Create another class called Polygon that has the following members;numPoints - a private instance member, an int, that describes the number of Points in the;current Polygon.;points[] - an array of Points representing the list of points that define this Polygon. This is;a private instance member.;MAX_POINTS - a static final that gives the maximum number of Points allowed in the array;(can be used to declare the array if you wish). Note that numPoints could be much smaller;than MAX_POINTS. For example, you might choose MAX_POINTSto be 100, but three;different objects might have numPoints set to 3, 13 and 7.;You should supply all of the following (at a minimum);A Constructor that takes no parameters and sets the number of points to 0.;A Constructorthat takes three parameters.;The first parameter is an int: numPoints, which indicates how many points the newly;constructed Polygon will contain.;The second is an array of floats: xArray[], which contains all the x-coordinates of;the Points in the newly constructed Polygon.;The third is an array of floats: yArray[], which contains all the y-coordinates of;the Points in the newly constructedPolygon.;For example, the x-y coordinates of the first (really 0th) Point in the Polygon would come;from xArray[0] and yArray[0], the x-y coordinates of the second (really 1st) Point in;the Polygon would come from xArray[1] and yArray[1], the x-y coordinates of the third;(really 2nd) Point in the Polygon would come from xArray[2] and yArray[2], and so on. (The;two arrays are called parallel arrays because they work together "in parallel" to specify;the Points: if you want to get the coordinates of the kth Point in the Polygon, you would;use the xArray[k - 1] for the x-coordinate and yArray[k - 1] for the y-coordinate.);The actual arrays passed might be larger than the int numPoints passed, and that's okay.;We only use the first numPointselements of the two arrays. For example, the arrays might;each be 100 elements, but if numPoints is 3, we are only using the first three elements of;each array. Only supply these two constructors and no others.;boolean setPoints(int numPoints, float xValues[], float yValues[]) - a mutator that takes;an int, numPoints, and twofloat arrays. The two float arrays provide the x-y;coordinates of the Points in the requested Polygon in the same manner described in detail;for the constructor, above. This method overwrites any values in the existing object, and;creates a fresh Polygon from scratch - it does not append points to the existing;Polygon. Return false (error) if the internal points[] array is smaller than numPoints or;if numPoints is < 0. There is another possible reason for failure (false return) that you must;consider - this is part of your assignment. Do not ask what it is, but figure it out based on the;information above.;void showPolygon() - displays the points in the Polygon as a text string such as "(3.5, 1.2);(-9.1, 5.5), (0.120, -0.30)",....;boolean addPoint(float x, float y) - adds (appends) a new Point to the list, but only if;there is room!;boolean addPoint (Point p) - adds (appends) a new Point to the list, but only if there is;room!;As always, make sure that mutators, constructors and any methods that affect private data filter;out bad parameters from the client.;This example gives lots of opportunity to use/invoke some methods to make other methods' lives;easier. Make sure you are not duplicating code, but exploiting this opportunity.;We don't care if a Polygon's points cause it to be drawn with sides crossing (if we were to draw it;which most of you will not). Any list of (x,y) pairs will be considered a valid Polygon, assuming that;they are valid Points.;Polygon and Point should be classes distinct from (and not contained within) your main class (which;we call Foothill). However, you can and should defined them as a non-public classes so it can;reside in the same file,;Generate a sample main() that tests your classes.;Establish one set of min/max values for the statics in the Point class using the static mutator.;set and display a few Point objects manually. Check that your range limitation works by;attempting to set values of one Pointoutside the range and proving that your Point rejects;this attempt.;Next, instantiate three Polygons manually from literal values in your program, i.e., do not;involve the user with run-time input.;Two Polygons should be constructed with float arrays arguments for the x and y values;instantly populating the Polygon. The third should be instantiated using the default;constructor, then filled with points using the mutator methods. Use different coordinate;values for the Points for all three Polygons (i.e., don't create two identical Polygons).;Display the Polygons.;Make changes to the Polygons using the mutators of that class and display them again.;In at least one Polygon mutator call, attempt to set values illegally (in any sense of the word;based on the above criteria) and prove that your class protects against this attempt.


Paper#67154 | Written in 18-Jul-2015

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