COMP 14: Midterm Review

1. COMP 14: Midterm Review June 8, 2000 Nick Vallidis

2. Announcements • Midterm is tomorrow!

3. Assignment P4 • Just want to go over it to make sure you all understand...

4. Instantiating objects • We do this with the keyword new • Examples: String name; name = new String("Vallidis"); Die myDie; myDie = new Die(6);

5. packages • A package is a group of classes • That's it. In Java, each class has its own .java file and all the .java files in a directory are one package.

6. Assignment operators mult += value is just the same thing as: mult = mult + value • This is just a shortcut so you don't have to type mult twice! • You can replace + with any of the normal math operators: -, /, %, etc.

7. Equivalence of loops • All loops have the same four parts: • initialization • condition • statements (the loop body) • increment (the loop update -- it doesn't have to be an increment specifically) • As a result, you can convert between loop types.

8. Equivalence of loops for (initialization; conditon; update) body; initialization; initialization; while (condition) do { { body; body; update; update; } } while (condition);

9. Nested if statements • What's up with this? if (x < 3) if (y > 2) System.out.println("yay!"); else System.out.println("x >= 3");

10. Nested if statements • write nested ifs to do the following: • you have one integer x • when 0<=x<5 print "low" • when 5<=x<10 print "medium" • when 10<=x<15 print "high" • for any other value of x don't do anything ------------------------------------------------------ • Can you do this as a switch statement?

11. nested loops • what does this code do? int i, j; for (i=1; i<=5; i++) { for (j=i; j>=1; j--) System.out.print("*"); System.out.println(); }

12. nested loops • Write code to print out a person's name 5 times and then ask if they want to do it again. If they do, then print their name again 5 times (response can be string or integer) Assume the name has already been read and has this declaration: String name;