Trouble

Question 1

ArithmeticException

Runtime or Checked Exception?

Answer 1

Runtime Exception

Question 2

ArrayIndexOutOfBoundsException

Runtime or Checked Exception?

Answer 2

Runtime Exception

Question 3

ClassCastException

Runtime or Checked Exception?

Answer 3

Runtime Exception

Question 4

IllegalArgumentException

Runtime or Checked Exception?

Answer 4

Runtime Exception

Question 5

NullPointerException

Runtime or Checked Exception?

Answer 5

RuntimeException

Question 6

NumberFormatException

Runtime or Checked Exception?

Answer 6

Runtime Exception

Question 7

FileNotFoundException

Runtime or Checked Exception?

Answer 7

Checked Exception

Question 8

IOException

Runtime or Checked Exception?

Answer 8

Checked Exception

Question 9

Does StringBuilder test for object equality or same letters with the .equals() method?

Answer 9

Object Equality

Question 10

The type of the object determines…

Answer 10

which properties exist within the object in memory

Question 11

The type of the reference to the object determines…

Answer 11

which methods and variables are accessible to the java program

Question 12

What can you not do with the Period class?

Answer 12

Chain methods!

Question 13

How to define an ArrayList that can have different types in it

Answer 13

ArrayList differentTypes = new ArrayList()

I guess just don’t specify type

Question 14

Can you override the finalize() method?

Answer 14

Yes

Question 15

Cab you pass null to varargs?

Answer 15

yes, but trying to access an index will result in NullPointerException

Question 16

For LocalDate d, is there a difference between

d.minus(p)

and

d = d.minus(p)

Answer 16

Yes.

You must do d = d.minus(p);

Question 17

If using a variable name as one of the cases in a switch statement, what modifier must it have?

Answer 17

final

Note: watch out for a final variable having the same value as a literal in the cases!

Question 18

Does System.gc() guarantee garbage collection will run?

Answer 18

No, it just hints at it

Question 19

What is wrong with this?

List list = new List()

Answer 19

List is an interface, so it cannot be instantiated directly!

Basically it can only be on the left side of this equation and you would want

List list = new ArrayList()

Question 20

Can you have calls to both super() and this() in a constructor?

Answer 20

No, only one or the other. One way to reason this is that any call to super() or this() must be the first non-comment line in a constructor, and they can’t both go first.