Abstraction and Program Design

Unit 3: Class Creation. Topics 3.1–3.2. This set has 61 questions. Each time the page loads you get five of them, chosen at random. Pick an answer, press Check answer, and read the explanation for every choice. Reload the page or use New questions for a fresh five.

Topics assessed

• 3.1 Abstraction and Program Design
• 3.2 Impact of Program Design

Practice questions

Essential knowledge for this set

These are the essential knowledge (EKS) statements from the AP Computer Science A Course and Exam Description that the 61 questions in this set assess, grouped by topic and learning objective. The table under each question links here.

Topic 3.1: Abstraction and Program Design

3.1.A — Represent the design of a program by using natural language or creating diagrams that indicate the classes in the program and the data and procedural abstractions found in each class by including all attributes and behaviors.

• 3.1.A.1 Abstraction is the process of reducing complexity by focusing on the main idea. By hiding details irrelevant to the question at hand and bringing together related and useful details, abstraction reduces complexity and allows one to focus on the idea.
• 3.1.A.2 Data abstraction provides a separation between the abstract properties of a data type and the concrete details of its representation. Data abstraction manages complexity by giving data a name without referencing the specific details of the representation. Data can take the form of a single variable or a collection of data, such as in a class or a set of data.
• 3.1.A.3 An attribute is a type of data abstraction that is defined in a class outside any method or constructor. An instance variable is an attribute whose value is unique to each instance of the class. A class variable is an attribute shared by all instances of the class.
• 3.1.A.4 Procedural abstraction provides a name for a process and allows a method to be used only knowing what it does, not how it does it. Through method decomposition, a programmer breaks down larger behaviors of the class into smaller behaviors by creating methods to represent each individual smaller behavior. A procedural abstraction may extract shared features to generalize functionality instead of duplicating code. This allows for code reuse, which helps manage complexity.
• 3.1.A.5 Using parameters allows procedures to be generalized, enabling the procedures to be reused with a range of input values or arguments.
• 3.1.A.6 Using procedural abstraction in a program allows programmers to change the internals of a method (to make it faster, more efficient, use less storage, etc.) without needing to notify method users of the change as long as the method signature and what the method does is preserved.
• 3.1.A.7 Prior to implementing a class, it is helpful to take time to design each class including its attributes and behaviors. This design can be represented using natural language or diagrams.

Topic 3.2: Impact of Program Design

3.2.A — Explain the social and ethical implications of computing systems.

• 3.2.A.1 System reliability refers to the program being able to perform its tasks as expected under stated conditions without failure. Programmers should make an effort to maximize system reliability by testing the program with a variety of conditions.
• 3.2.A.2 The creation of programs has impacts on society, the economy, and culture. These impacts can be both beneficial and harmful. Programs meant to fill a need or solve a problem can have unintended harmful effects beyond their intended use.
• 3.2.A.3 Legal issues and intellectual property concerns arise when creating programs. Programmers often reuse code written by others and published as open source and free to use. Incorporation of code that is not published as open source requires the programmer to obtain permission and often purchase the code before integrating it into their program.