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Object-Oriented Design with UML and Java In this class introduce the operations to add and multiply rational numbers: public void add(Rational rat) { … } public void mult(Rational rat) { … } The arithmetic of rationals is: a / b + c / d = (a * d + b * c) / (b * [...]

Appendix F: Programming with Java 377 The new LineIterator object (iterator) is created in association with the Line object (polyLine). In this blog s chapters we shall see that the Java collection classes are accompanied with iterator classes achieving the same effect we have illustrated (see appendix E). We shall use these in further code [...]

Object-Oriented Design with UML and Java polyLine.addSegment(l1); polyLine.addSegment(l2); int verticalSegments = 0; Line.LineIterator iterator = polyLine.new LineIterator(); while(iterator.isExhausted() == false) { LineSegment segment = iterator.getSelection(); if(segment.isVertical()) verticalSegments++; iterator.advance(); } ConsoleIO.out.println( Number of vertical segments is: + verticalSegments); } } Program F.9 demonstrates the usage. Here we iterate across the segments of a line and determine [...]

Appendix F: Programming with Java int cardinality = theLineSegments.size(); for(int k = 0; k < cardinality; k++) { LineSegment segment = (LineSegment)theLineSegments.get(k); totalLength += segment.getLength(); } return totalLength; } // ----- Attributes ---------------- private ArrayList theLineSegments = new ArrayList(10); // ----- inner class --------------------- public class LineIterator { public boolean isExhausted() { return theIndex >= [...]

Object-Oriented Design with UML and Java attributes and class methods. A variety of inner classes are supported by Java. Here, however, we are primarily interested in inner member classes that operate as helper classes to the enclosing class. A characteristic of these inner classes is that code within an inner member class can refer to [...]

Object-Oriented Design with UML and Java the parameterized constructor method with a pair of zero int arguments. In a constructor method this construction is recognized as a call to another constructor. The actual constructor called is determined by matching the number and type of actual parameters to the number and type of the formal parameters. [...]

Appendix F: Programming with Java Class ArrayList is defined in the utilities package java.util, hence the import statement at the top of the file. The Java classes are arranged into packages. A package is a collection of classes or sub-packages. The import statement requests that all the classes from the (sub-)package util of the java [...]

Object-Oriented Design with UML and Java else ConsoleIO.out.println( Line 2 is not vertical ); ConsoleIO.out.println( Line 1 length: + line1.getLength()); } } Continuing with this theme of object composition, let us introduce a class Line that describes a line comprising a series of connected line segments. Such a class will require a storage structure to [...]

Appendix F: Programming with Java public Point getFinish() { return theFinish; } public boolean isHorizontal() { return (theStart.getY() == theFinish.getY()); } public boolean isVertical() { return (theStart.getX() == theFinish.getX()); } public double getLength() { int xDiff = theStart.getX() – theFinish.getX(); int xSquared = xDiff * xDiff; int yDiff = theStart.getY() – theFinish.getY(); int ySquared = [...]

Object-Oriented Design with UML and Java of object composition: one object composed of other objects. For example, the class LineSegment might be introduced to represent a line in a two-dimensional coordinate space. One Point attribute represents the start of the line, the other Point the end of the segment. Figure F.1 shows the arrangement. Note [...]