Spring Semester 2005

boolean
s, Conditions, Decisions
First off here are some problems you need to have worked out before you leave the lab.
1
, 2
,
3
, or 4
(as an integer)
and reports "one
",
"two
", "three
", or
"four
" depending on the number that was
entered. If the number does not match the program prints "sorry".
50
and 50
every time you call it.
123
" and
adds its digits to produce 6
.
(Use charAt(
...)
instead of
substring(
...)
).
23:59
" and
creates two integers out of it, one for the hours (23
, in
this case) and one for the minutes (59
, here).
3.85
into an A
(by printing the letter grade A
to the
screen in response), numbers between
3.5
and 3.85
into an A
, numbers
between 3.15
and 3.5
into a B+
and
all the other numbers into an "Unknown
" type of message.
So before you leave you need to be able to correctly answer or solve all of the problems above. You should get help from the lab instructor if you're having problems putting the right answer together.
And now the Lab Assignment for next time:
Questions to work with for practice:
if
statements.
if quarters > 0 then System.out.println(quarters + "quarters"); if (1 + x > Math.pow(x, Math.sqrt(2)) y = y + x; if (x = 1) y++; else if (x = 2) y = y + 2; if (x && y == 0) p = new Point2D.Double(x, y); if (1 <= x <= 10) { System.out.println("Enter y:"); y = console.readDouble(); } if (s != "nickels"  s != "pennies"  s != "dimes"  s != "quarters") System.out.print("Input error!"); if (input.equalsIgnoreCase("N")  "NO") return; int x = console.readDouble(); if (x != null) y = y + x; language = "English"; if (country.equals("USA")) if (state.equals("PR")) language = "Spanish"; else if (country.equals("China")) language = "Chinese";
if
statements?
if
statement where the order of the tests does not matter.
Give an example where the order of the tests matter.
"Tom", "Dick" "Tom", "Tomato" "church", "Churchill" "car manufacturer", "carburetor" "Harry" hairy" "C++", "Car" "Tom", "Tom" "Car", "Carl" "car", "bar"
p
, q
,
and r
.
p 
q 
r 
(p && q)  !r 
!(p && (q  !r)) 

false  false  false  ?  ? 
false  false  true  ?  ? 
false  true  false  ?  ? 
?  ?  ?  ?  ? 
?  ?  ?  ?  ? 
?  ?  ?  ?  ? 
?  ?  ?  ?  ? 
?  ?  ?  ?  ? 
A && B
is the same as B && A
for any Boolean
conditions A
and B
?
ands = 0; if (x > 0) s++; if (y > 0) s++;
s = 0; if (x > 0) s++; else if (y > 0) s++;
!(x > 0 && y > 0) !(x != 0  y != 0) !(country.equals("USA") && !state.equals("HI") && !state.equals("AK")) !(x % 4 != 0  !(x % 100 == 0 && x % 400 == 0))
else
problem, using the following statement. A student with a GPA of at least 1.5, but less
than 2, is on probation. With less than 1.5, the student is failing.
==
operator and the
equals
method when comparing strings.
andr == s
where bothr.equals(s)
r
and s
are of type Rectangle
.
r
is null
?
What happens when this code runs?
Rectangle r; ... if (r.equals(null)) r = new Rectangle(5, 10, 20, 30);
Line2D.Double
represent the same line when displayed
on the graphics screen. Do not use a.equals(b)
.
Hint: IfLine2D.Double a; Line2D.Double b; if (your condition goes here) g2.drawString("They look the same!", x, y);
p
and q
are
points, then Line2D.Double(p, q)
and
Line2D.Double(q, p)
look the same.
n
equals
10 and whether a floatingpoint number x
equals 10.
x
and y
such that Math.abs(x  y)
is larger than 1000, but x
and
y
are still identical except for a roundoff error.
Rewrite this code to eliminate the explicitPoint2D.Double p = ... boolean xInside = false; if (x1 <= p.getX() && p.getY() <= x2) xInside = true; boolean yInside = false; if (y1 <= p.getY() && p.getY() <= y2) yInside = true; if (xInside && yInside) g2.drawString("p is inside the rectangle.", x1, y1);
true
and false
values,
by setting xInside
and yInside
to the values of Boolean expressions.
Thu Feb 3 15:14:08 EST 2005