📚 Topic Summary
In Java, strings are immutable sequences of characters. String methods allow you to manipulate these sequences without changing the original string. Instead, these methods return a new string representing the result of the operation. Understanding these methods is crucial for any AP Computer Science A student, as they appear frequently in coding problems and free-response questions. They allow you to extract parts of strings, compare strings, change the case of letters, and more!
🧠 Part A: Vocabulary
Match the term with its definition:
| Term |
Definition |
| 1. Substring |
A. Compares two strings lexicographically. |
| 2. IndexOf |
B. Converts a string to lowercase. |
| 3. equals() |
C. A contiguous sequence of characters within a string. |
| 4. toLowerCase() |
D. Checks if two strings have the same value. |
| 5. compareTo() |
E. Returns the index of the first occurrence of a specified substring. |
✍️ Part B: Fill in the Blanks
Complete the following paragraph using the words: length, charAt, immutable, concat, trim.
Strings in Java are ______________, meaning their value cannot be changed after creation. The __________ method returns the number of characters in a string. You can use the ___________ method to retrieve a character at a specific position. To combine two strings, you can use the __________ method. Finally, __________ removes leading and trailing whitespaces from a string.
🤔 Part C: Critical Thinking
Explain, with code examples, why string methods in Java do not modify the original string object.