Except where otherwise noted, the contents of this document are Copyright 2010 Stuart Reges and Marty Stepp.
lab document created by Whitaker Brand and Marty Stepp
Goals for today:
For each expression in the left-hand column, indicate its value in the right-hand column. Be sure to list a constant of appropriate type (e.g., 7.0 rather than 7 for a double, Strings in quotes).
4 * (2 + 4) - 3 * 5
|
9 |
|
54 % 10 + 8 * 3 % 9
|
10 |
|
3 * 2 + 4 + "+" + 2 + 3 * 4
|
"10+212" |
|
2.3 * 3 + 19 / 5 / 2 + 6.0 / 5
|
9.1 |
|
108 / 20 * 3 / 4 / 2.0 + 1.0 / 2
|
2.0 |
public class Mystery { public static void main(String[] args) { String hear = "bad"; String song = "good"; String good = "hear"; String walk = "talk"; String talk = "feel"; String feel = "walk"; claim(feel, song, feel); // to walk the walk is good claim(good, hear, song); // to hear the good is bad claim(talk, "song", feel); // to feel the walk is song claim("claim", talk, walk); // to claim the talk is feel } public static void claim(String hear, String good, String song) { System.out.println("to " + hear + " the " + song + " is " + good); } }
if
/else
mystery
Consider the following Java code.
public static void ifElseMystery(int a, int b) { if (a < b) { a = a * 2; } if (a > b) { a = a - 10; } else { b++; } System.out.println(a + " " + b); }
Fill in the boxes with the output produced by each of the method calls.
ifElseMystery(10, 3);
|
0 3 |
|
ifElseMystery(6, 6);
|
6 7 |
|
ifElseMystery(3, 4);
|
-4 4 |
|
ifElseMystery(4, 20);
|
8 21 |
while
loop
mystery
Fill in the boxes at right with the output produced by each method call.
public static void mystery(int n) { int x = 1; int y = 2; while (y < n) { if (n % y == 0) { n = n / y; x++; } else { y++; } } System.out.println(x + " " + n); } |
|
Identify whether each assertion is always/never/sometimes true
at each point.
public static void mystery(int x, int y) { int z = 0; // Point A while (x != y) { // Point B z++; if (x > y) { // Point C x = x / 10; } else { // Point D y = y / 10; } } // Point E System.out.println(x + " " + y + " " + z); }
Solve this problem in Practice-It by clicking on the check-mark above.
Write a method flip
that takes a Random
object as
a parameter and that prints information about a coin-flipping simulation.
Your method should use the Random
object to produce a sequence
of simulated coin flips, printing whether each flip comes up "heads" or
"tails". Each outcome should be equally likely. Your method should stop
flipping when you see three heads in a row.
Solve this problem in Practice-It by clicking on the check-mark above.
Write a method before
that takes as parameters two month/day
combinations and that returns whether or not the first date comes before
the second date (true
if the first month/day comes before the
second month/day, false
if it does not). The method will take
four integers as parameters that represent the two month/day combinations.
The first integer in each pair represents the month and will be a value between 1 and 12 (1 for January, 2 for February, etc, up to 12 for December). The second integer in each pair represents the day of the month (a value between 1 and 31). One date is considered to come before another if it comes earlier in the year.
Solve this problem in Practice-It by clicking on the check-mark above.
Write a method sameDashes
that takes two strings as parameters
and that returns whether or not they have dashes in the same places
(returning true
if they do and returning false
otherwise). For example, below are four pairs of strings of equal length
that have the same pattern of dashes. Notice that the last pair has no
dashes at all.
string 1: "hi--there-you." "-15-389" "criminal-plan" "abc" string 2: "12--(134)-7539" "-xy-zzy" "(206)555-1384" "9.8"To be considered a match, the strings must have exactly the same number of dashes in exactly the same positions. The Strings might be of different length.
Solve this problem in Practice-It by clicking on the check-mark above.
If you finish all the exercises, work on other sample midterm questions in Practice-It.