Ch 6 & 7 Quiz 4

Question 1

Study #2

Answer 1

2

Question 2

T/F: the interface of a class describes what a class does and how it can be used by showing the implementation

Answer 2

F: the interface of a class describes what a class does and how it can be used without showing the implementation

Question 3

The word interface in Java can be used as___

Answer 3

Class interface
Graphical User Interface
Method interface
Language construct

Question 4

Study #6

Answer 4

Study #6

Question 5

Question 7

Answer 5

Q 7

Question 6

T/F: an object is said to be immutable if it’s contents or state cannot be changed once it has been created. Strings are an example of immutable objects.

Answer 6

T

Question 7

Will this code compile and if not what line would cause the error?
…
String userAnswer = reader.getInput().trim().toLowerCase();
String rightAnswer = “java is democratic” + 3;
int calcResult = 5 + 1;
int rightResult = 5;

if (calcResult == rightResult && userAnswer == rightAnswer)
{
System.out.println(“Maybe you are right”)
}
…

Answer 7

Code will compile because the syntax is correct

Question 8

Auto-boxing

Answer 8

Where the compiler take the decision to convert a primitive value (ex: int) into an object of its wrapper class (ex: Integer)

Study #12

Question 9

Auto-unboxing

Answer 9

Where the compiler take a decision to covert an object of a wrapper class (ex: Integer) into its primitive value (ex: int)

Study #12

Question 10

javadoc comment

Answer 10

The comment start symbol must have 2 asterisks.

/**
This is a javadoc comment
*/

Question 11

Study 15

Answer 11

Study 15

Question 12

T/F: The following code will compile correctly:
…
public class MyVote
{
private static int voteResult = 0;
private int voteID = 0;
private static final int voteTruth = voteResult + voteID;
}

Answer 12

F: static variable can’t refer to non-static variable. voteTruth (static variable) is referring to voteID (non-static)

Question 13

17

Answer 13

17

Question 14

Study #20

Answer 14

20