Decisions - Java Concepts - page 305

Rectangle r;
. . .
if (r.equals(null))
r = new Rectangle(5, 10, 20, 30);

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΢ Exercise R5.15 Explain how the lexicographic ordering of strings differs

from the ordering of words in a dictionary or telephone book. Hint:
Consider strings, such as IBM, wiley.com, Century 21,
While-U-Wait , and 7-11.

΢΢΢ Exercise R5.16. Write Java code to test whether two objects of type
Line2D.Double represent the same line when displayed on the
graphics screen. Do not use a.equals(b) .

Line2D.Double a;
Line2D.Double b;
if (your condition goes here)
g2.drawString(ÐThey look the same!Ñ, x, y);

Hint: If p and q are points, then Line2D.Double(p, q) and
Line2D.Double(q, p) look the same.

΢ Exercise R5.17. Explain why it is more difficult to compare floating-point

numbers than integers. Write Java code to test whether an integer n equals
10 and whether a floating-point number x equals 10.

΢΢ Exercise R5.18 Consider the following test to see whether a point falls
inside a rectangle.

Point2D.Double p = . . .
Rectangle r = . . .
boolean xInside = false;
if (r.getX() <= p.getX() && p.getX() &= r.getX()
+ r.getWidth())
xInside = true;
boolean yInside = false;
if (r.getY() <= p.getY() && p.getY() <= r.getY()
+ r.getHeight())
yInside = true;
if (xInside && yInside)
g2.drawString(Ðp is inside the rectangle.Ñ,
p.getX(), p.getY());