#AP Computer Science A: String Manipulation Study Guide 🚀

Hey there, future AP Computer Science A rockstar! This guide is designed to be your ultimate resource for mastering String manipulation, especially as you gear up for the big exam. Let's dive in and make sure you're feeling confident and ready to ace it!

#Introduction to External Libraries and APIs

#What are External Libraries and APIs?

• Java's base installation is powerful, but external libraries and APIs expand its capabilities.
• These resources provide pre-written code for common tasks, saving you time and effort.
• Think of them as toolboxes filled with specialized tools for your coding projects. 🧰

#Java Documentation

• Every Java class, library, and API comes with documentation.
• Documentation lists available methods and how to use them.
• Check out the official Java documentation for the String class here: String Class Documentation

#The String Class

• The String class is part of the java.lang package.

• Classes in java.lang are automatically imported, so no need to import them manually. 🎉

#String Methods: Accessing Substrings

#Key Concepts

• Substring: A sequence of characters within a larger string.
• Character: A substring with a length of 1. - Zero-Indexed Language: Java starts counting at 0, not 1. 🤯

#length() Method

• int length(): Returns the number of characters in the string.

java String str = "Hello"; int len = str.length(); // len will be 5 ```

#substring() Method

• String substring(int beginIndex, int endIndex): Returns a substring from beginIndex up to (but not including) endIndex.
• String substring(int beginIndex): Returns a substring from beginIndex to the end of the string.

java String str = "Peter Cao"; String sub1 = str.substring(0, 5); // sub1 will be "Peter" String sub2 = str.substring(6); // sub2 will be "Cao" ```

#Accessing the nth Character

• Use `str.substring(n-1...