Chapter 4: Methods and Encapsulation

Question 1

What parts of a method are required for the code to compile?

Answer 1

Return type
Method name
Parameter list (can be empty ())
Method body (can be empty {})

Question 2

What are the access modifiers in order from most to least accessible?

Answer 2

public
protected
[default]
private

Question 3

Can a package private class be accessed from a child class in a different package?

Answer 3

No. Package private is default accessibility and can only be accessed within the same package.

Question 4

What does final mean when applied to a method?

Answer 4

The method cannot be overridden

Question 5

What is the syntax for a method’s exception list?

Answer 5

Keyword throws followed by a comma separated list of exceptions

throws Exception1, Exception2, …

Question 6

What is the correct syntax for varargs?

Answer 6

datatype… name

Question 7

What are the rules for using varargs parameter?

Answer 7

It must be the last parameter and there can be only one vararg in a given parameter list

Question 8

How do you pass data to a method with a vararg?

Answer 8

Data can be passed in as comma separated values or as an array

Question 9

How do you access data from a vararg within a method?

Answer 9

Treat it like an array

Question 10

When can you call methods on a null reference variable?

Answer 10

When the method is static

Question 11

Can a static member call an instance member?

Answer 11

No

Question 12

What runs first, static initializer or intance initializer?

Answer 12

Static

Question 13

When is the last time a value can be assigned to a final instance variable?

Answer 13

In the constructor

Question 14

When do static initializer blocks run?

Answer 14

When the class is first used

Question 15

What do static imports do?

Answer 15

Allow importing of static class members

Question 16

Is Java a pass-by-reference language?

Answer 16

No. Java is pass-by-value

Question 17

What is the order in which Java will match overloaded methods?

autoboxed type
larger primitive type
varargs
exact type match

Answer 17

exact type match
larger primitive type
autoboxed type
varargs

Question 18

Can a class constructor have a different name than the class it’s in?

Answer 18

No

Question 19

Can a constructor have a return type?

Answer 19

No

Question 20

If a class only has a private constructor, is a default constructor provided?

Answer 20

No

Question 21

How do you call other constructors within the same class?

Answer 21

Using this()

Question 22

What is the order of initialization?

constructor
superclass
instance variable declaration and instance initializers in the order they appear
static variable declaration and static initializers in the order they appear

Answer 22

superclass
static variable declaration and static initializers in the order they appear
instance variable declaration and instance initializers in the order they appear
constructor

Question 23

List five JavaBeans conventions

Answer 23

properties are private
getters begin with ‘is’ if the property is a boolean
getters begin with ‘get’ if the property is not boolean
setters begin with ‘set’
methods are camelcase

Question 24

How do you create an immutable class?

Answer 24

Make instance variables private
Don’t provide setters
set initial values in the constructor

Question 25

When can you omit the parenthesis around a lambda expression’s parameter?

Answer 25

When there is exactly one parameter without an explicitly specified type

Question 26

When do you need to provide a return statement in a lambda expression?

Answer 26

When using a code block for the right side of the expression ( {} )