AP CSA 总复习 | 现代数学启蒙

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UNIT 1: Primitive Types

This unit covers the basic data types in Java, such as int, double, boolean, and char. It also includes understanding variables, assignment statements, and arithmetic operations.

Code Examples:

Variable Declaration and Initialization:

Arithmetic Operations:

Increment and Decrement:

Type Casting:

Combining Operations:

Math Class Usage:

Character Operations:

Boolean Logic:

Simple Output:

Simple Input (Using Scanner):

UNIT 2: Using Objects

This unit introduces object-oriented programming concepts, focusing on object creation, method calls, and the String class in Java.

Code Examples:

String Concatenation:

String Methods:

Creating Objects:

Using Scanner for Input:

Using Math Class:

Date and Time (Using LocalDate):

Random Numbers (Using Random):

Formatting Strings (Using String.format):

StringBuilder for Efficient String Manipulation:

Parsing Strings to Primitives:

UNIT 3: Boolean Expressions and if Statements

This unit covers the use of boolean expressions and conditional statements in Java.

Code Examples:

Simple If Statement:

If-Else Statement:

If-Else-If Ladder:

Nested If Statements:

Boolean Logical Operators:

Switch Statement:

Ternary Operator:

Comparing Strings:

Boolean Variable:

Complex Conditions:

UNIT 4: Iteration

This unit focuses on loops and iteration, including for, while, and do-while loops.

Code Examples:

Simple For Loop:

Enhanced For Loop:

While Loop:

Do-While Loop:

Nested Loops:

Loop Control - Break:

Loop Control - Continue:

Infinite Loop:

Countdown Loop:

Summing Values in a Loop:

UNIT 5: Writing Classes

This unit introduces the concept of designing and implementing classes in Java, including constructors, methods, and fields.

Code Examples:

Defining a Simple Class:

Creating and Using an Object:

Adding Methods to a Class:

Using the this Keyword:

Overloading Constructors:

Encapsulation with Getters and Setters:

Static Methods and Fields:

Method Overloading:

Inheritance Basics (Extending a Class):

Unit 6 Array

Arrays are data structures that store a fixed-size sequential collection of elements of the same type. They are used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type.

Key Concepts:

Declaration, instantiation, and initialization of arrays.

Accessing elements, iterating through arrays.

Limitations and characteristics of arrays (fixed size, same data type).

UNIT 7: ArrayList

ArrayList in Java is a resizable array, which can be found in the java.util package. Unlike traditional arrays, ArrayLists can change size dynamically.

Key Concepts:

Creating and using ArrayLists.

Adding, removing, and accessing elements.

Comparing ArrayLists with standard arrays.

Example Code:

UNIT 8: 2D Array

2D arrays are arrays of arrays, often used to represent matrices or grids. They are particularly useful for programs that require a lot of data organization, such as games or simulations.

Key Concepts:

Declaration, instantiation, and initialization of 2D arrays.

Accessing and modifying elements.

Nested loops for iteration.

Example Code:

UNIT 9: Inheritance

Inheritance is a fundamental concept in object-oriented programming that allows a new class to inherit properties and methods from an existing class. This promotes code reuse and establishes a hierarchical relationship between classes.

Key Concepts:

Understanding base (superclass) and derived (subclass) classes.

Overriding methods.

super keyword for accessing superclass methods and constructors.

Polymorphism and dynamic method dispatch.

Example Code:

UNIT 10: Recursion

Recursion is a programming technique where a method calls itself to solve a problem. It's a powerful tool, especially for tasks that can be defined in terms of similar subtasks.

Key Concepts:

Understanding recursive methods.

Base case and recursive case.

Stack overflow and termination conditions.

Recursive algorithms (e.g., factorial, Fibonacci).

Example Code: