Java Programming Principles

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Questions and Answers

What is the problem with the code snippet: `expenses = new Expenses(100, 10); employee.getDepartment().getManager().approveExpense(expenses);`?

It is a violation of the Law of Demeter (correct)

The method names are not descriptive

The code does not handle errors properly

The classes are not properly instantiated

What is the effect of the tightly coupled classes in the code?

Improved code readability

Reduced cohesion (correct)

Higher modularity

Easier debugging

What is the benefit of following the Law of Demeter?

Improved code performance

Increased modularity and flexibility (correct)

Easier debugging

Reduced code complexity

What is a characteristic of a well-designed function according to the Law of Demeter?

It has a single responsibility Signup and view all the answers

What is an effect of a global variable accessible by all classes?

Tighter coupling between classes Signup and view all the answers

What is the main principle of the Law of Demeter?

A method of an object should only call methods of a limited set of objects Signup and view all the answers

What is a challenge of object-oriented code?

It makes it hard to add new functions because all the existing classes must change. Signup and view all the answers

When is procedural code more appropriate?

When we want to add new functions more than data types. Signup and view all the answers

What is the principle of the Law of Demeter?

A module should not know about the inner details of the objects it manipulates. Signup and view all the answers

What is a consequence of not following the Law of Demeter?

Tight coupling between objects. Signup and view all the answers

What is the main idea behind the Law of Demeter?

A method should only call the methods of its own class, its parameters, and any objects created within it. Signup and view all the answers

What is the alternative way to describe the Law of Demeter?

Only talk to your immediate friends. Signup and view all the answers

What is the primary goal of abstraction in data structures?

To hide the internal details of the data Signup and view all the answers

What is the main difference between data structures and objects?

Data structures are public and have no functions, while objects are private and have functions Signup and view all the answers

What would happen if a new function is added to the Geometry class in the Procedural Shape Example?

The shape classes would be unaffected Signup and view all the answers

What is the advantage of using object-oriented programming in the Polymorphic Shapes Example?

It makes it easy to add new shapes without changing the existing functions Signup and view all the answers

What is the concept demonstrated by the Procedural Shape Example and the Polymorphic Shapes Example?

Data/Object Anti-Symmetry Signup and view all the answers

What is the main difference between procedural code and object-oriented code in terms of adding new functions and data structures?

Procedural code makes it hard to add new data structures, while object-oriented code makes it easy to add new functions Signup and view all the answers

Study Notes

Object-Oriented vs Procedural Code

OO code makes it hard to add new functions because all existing classes must change
OO code makes it easy to add new classes without changing existing functions
Procedural code is the opposite: easy to add new functions, hard to add new classes

When to Use OO Code

In complex systems where new data types are likely to be added
When the primary focus is on adding new data types rather than functions

When to Use Procedural Code

When new functions are likely to be added, but not new data types
When the primary focus is on adding new functions rather than data types

The Law of Demeter (LoD)

States that a module should not know about the inner details of objects it manipulates
A software component or object should not have knowledge of the internal workings of other objects or components
LoD is a specific case of loose coupling

Law of Demeter Rules

A method M of class C should only call methods of:
- C itself
- M's parameters
- Any objects created within M
- C's direct component objects
- Global variables accessible by C, in the scope of M

Law of Demeter Principles

"Only talk to your immediate friends"
"Don't talk to strangers"
Abstract data representation, hiding internal details

Data/Object Anti-Symmetry

Objects hide their data (private) and have functions to operate on that data
Data structures show their data (public) and have no functions
Procedural code uses data structures, making it easy to add new functions but hard to add new data structures
OO code uses objects, making it easy to add new data structures but hard to add new functions

Law of Demeter Violation Example

Code that violates LoD allows method calls on objects returned by other methods, leading to tight coupling between classes

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Description

This quiz assesses understanding of Java programming principles, including static fields and the Law of Demeter. It covers concepts related to variable scope and method calling.