Class Design & Encapsulation

🏛️ Class Design

Part 1 of 7 — Static vs Instance, Scope, and Method Design

Static vs Instance

public class Counter {
    private static int totalCount = 0;  // Shared by ALL Counter objects
    private int myCount = 0;            // Unique to each Counter object

    public Counter() {
        totalCount++;
    }

    public void increment() {
        myCount++;
    }

    public static int getTotalCount() {
        return totalCount;      // OK - static method accessing static variable
        // return myCount;      // ERROR - static method cannot access instance variable
    }
}

🔑 Static variables are shared across all instances of a class. Changing it in one place changes it everywhere. Great for counting objects or shared constants.

Concept Check 🎯

Variable Scope

public class Example {
    private int x = 10;           // Instance: accessible everywhere in class

    public void demo(int y) {     // Parameter: accessible in demo()
        int z = 20;               // Local: accessible in demo()
        for (int i = 0; i < 5; i++) {  // Loop var: accessible in loop only
            // x, y, z, and i are all accessible here
        }
        // i is NOT accessible here
    }
    // y and z are NOT accessible here
}

Method Design Principles

Applied Recall ✍️

1. A variable declared with the static keyword is shared by all _______ of the class.

2. A variable declared inside a method is called a _______ variable and exists only while that method runs.

3. Having multiple methods with the same name but different parameter lists is called method _______.

Classify the Concept 🔍

AP Exam Strategy: Class Design

• Know the difference between static and instance — this determines how you call methods and access data
• Scope questions test whether a variable is accessible in a given context
• A static method CANNOT access instance variables (no this exists)
• Overloading: same name, different parameters. Overriding: subclass redefines superclass method (covered in inheritance)
• FRQ tip: when designing a class, always start with private instance variables, then write the constructor(s), then methods

AP-Style Application 🎯

💻 Class Design & Encapsulation

Part 2 of 7 — Key Processes

Understanding the processes related to Class Design & Encapsulation helps explain how and why patterns develop. This part explores the mechanisms driving key phenomena.

Key Concepts

Concept Check 🎯

Key Processes — Deeper Dive

Process 1

The primary mechanism that drives patterns in Class Design & Encapsulation. Understanding this concept is essential for mastering Class Design & Encapsulation in AP Computer Science A.

Process 2

A secondary process that shapes outcomes in Class Design & Encapsulation. This builds on the previous concept and connects to broader themes in the course.

Cause and effect

The relationship between actions and outcomes in Class Design & Encapsulation. This is frequently tested on the AP exam and connects to multiple units in the curriculum.

Applied Recall (exact term answers) ✍️

1. What term refers to the primary mechanism that drives patterns in Class Design & Encapsulation?

💻 Class Design & Encapsulation

Part 3 of 7 — Patterns & Examples

This part examines specific patterns and real-world examples related to Class Design & Encapsulation. Case studies help illustrate abstract concepts.

Key Concepts

Concept Check 🎯

Patterns & Examples — Deeper Dive

Spatial pattern

The geographic distribution related to Class Design & Encapsulation. Understanding this concept is essential for mastering Class Design & Encapsulation in AP Computer Science A.

Case study

A specific real-world example that illustrates Class Design & Encapsulation. This builds on the previous concept and connects to broader themes in the course.

Comparison

Analyzing similarities and differences across examples of Class Design & Encapsulation. This is frequently tested on the AP exam and connects to multiple units in the curriculum.

Applied Recall (exact term answers) ✍️

1. What term refers to the geographic distribution related to Class Design & Encapsulation?

💻 Class Design & Encapsulation

Part 4 of 7 — Connections & Interactions

Class Design & Encapsulation connects to other topics in AP Computer Science A. Understanding these connections reveals how different processes interact.

Key Concepts

Concept Check 🎯

Connections & Interactions — Deeper Dive

Interconnection

How Class Design & Encapsulation links to other course topics. Understanding this concept is essential for mastering Class Design & Encapsulation in AP Computer Science A.

Scale interaction

How Class Design & Encapsulation operates differently at local, national, and global scales. This builds on the previous concept and connects to broader themes in the course.

Feedback loop

How outcomes of Class Design & Encapsulation can reinforce or modify the original process. This is frequently tested on the AP exam and connects to multiple units in the curriculum.

Applied Recall (exact term answers) ✍️

💻 Class Design & Encapsulation

Part 5 of 7 — Change Over Time

Class Design & Encapsulation has evolved over time. Understanding historical and contemporary changes helps explain current patterns and predict future trends.

Key Concepts

Concept Check 🎯

Change Over Time — Deeper Dive

Continuity

Aspects of Class Design & Encapsulation that have remained stable over time. Understanding this concept is essential for mastering Class Design & Encapsulation in AP Computer Science A.

Change

How Class Design & Encapsulation has transformed due to new forces and conditions. This builds on the previous concept and connects to broader themes in the course.

Trend

The direction of change in Class Design & Encapsulation over time. This is frequently tested on the AP exam and connects to multiple units in the curriculum.

Applied Recall (exact term answers) ✍️

1. What term refers to aspects of Class Design & Encapsulation that have remained stable over time?

💻 Class Design & Encapsulation

Part 6 of 7 — Problem-Solving Workshop

Apply Class Design & Encapsulation concepts to data interpretation and analytical scenarios. Practice the types of questions seen on the AP exam.

Key Concepts

Concept Check 🎯

Problem-Solving Workshop — Deeper Dive

Data interpretation

Analyzing maps, graphs, and tables related to Class Design & Encapsulation. Understanding this concept is essential for mastering Class Design & Encapsulation in AP Computer Science A.

Argumentation

Making evidence-based claims about Class Design & Encapsulation. This builds on the previous concept and connects to broader themes in the course.

Spatial reasoning

Using geographic thinking to analyze Class Design & Encapsulation. This is frequently tested on the AP exam and connects to multiple units in the curriculum.

Applied Recall (exact term answers) ✍️

1. What term refers to analyzing maps, graphs, and tables related to Class Design & Encapsulation?

💻 Class Design & Encapsulation

Part 7 of 7 — AP Review

Comprehensive review of Class Design & Encapsulation for the AP exam. Focus on key concepts, common question types, and exam strategies.

Key Concepts

Concept Check 🎯

AP Review — Deeper Dive

Key vocabulary

Essential terms and definitions for Class Design & Encapsulation. Understanding this concept is essential for mastering Class Design & Encapsulation in AP Computer Science A.

Common question types

The most frequent ways Class Design & Encapsulation is tested on the AP exam. This builds on the previous concept and connects to broader themes in the course.

Exam strategy

Approaches for answering Class Design & Encapsulation questions effectively. This is frequently tested on the AP exam and connects to multiple units in the curriculum.

Applied Recall (exact term answers) ✍️

1. What term refers to essential terms and definitions for Class Design & Encapsulation?