11. Object oriented design

Question 1

What is the difference between a mutable and an immutable object?

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Question 2

What does import do for us?

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Question 3

Which package has all its classes imported automatically?

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Question 4

What are stubs used for?

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Question 5

What symbols are used to start and end a multi-line comment?

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Question 6

In object oriented design, in what sense is the design oriented around objects?

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Question 7

What two interesting things might nouns that appear in the requirements statements relate to?

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Question 8

How does the idea of encapsulation relate to the default of making our instance variables private?

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Question 9

What principles do we follow when deciding in which class our code should reside?

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Question 10

What is the name of the mechanism for passing arguments to methods in Java?

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Question 11

What is the significance of the approach for arguments of a primitive type and those of a reference type?

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Question 12

In what way must each constructor be distinguished from the others?

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Question 13

What two things are checked by the compiler in the multiple returns context?

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Question 14

What do we mean by the phrase ‘single entry, multiple exit’?

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Question 15

Which of the following method headings suggest they are accessor methods?

private void updateFeature()
public void updateFeature()
private int getFeature()
public int getFeature()
private static int getFeature()
public static int getFeature()
private void setFeature(int f)
public void setFeature(int f)

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Question 16

What kind of objects never have mutator methods?

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Question 17

What is the standard input used for?

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Question 18

What is a package?

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Question 19

What is a fully qualified name?

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Question 20

What is the range of the result of the method random()? Exactly?

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Question 21

What kinds of information does getProperty() give us? What is the return type?

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Question 22

Exactly how do we obtain the line separator?

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Question 23

What kind of Java variable is System.in?

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Question 24

What method is used to read lines of text? And what is used to read int values?

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Question 25

How does Java ensure the implicit toString() convention does not fail with null references?

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Question 26

What must be done to a final instance variable, by what stage, and what cannot be done later?

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Question 27

A class constant is another name for what?

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Question 28

Which object does null refer to?

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Question 29

Is it mutable or immutable objects for which having more than one variable holding its reference is particularly an issue, and why?

Answer 29

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