๐ Topic Summary
The Scanner class in Java is essential for reading input from various sources, most commonly the keyboard. For AP Computer Science A, mastering its use is crucial. It involves creating a Scanner object, specifying the input source (like System.in for keyboard input), and using methods like nextInt(), nextDouble(), and nextLine() to read different data types. Proper handling of input and closing the Scanner when finished are key to writing robust and efficient code.
Following best practices ensures that your code is readable, maintainable, and less prone to errors. This includes importing the Scanner class, initializing it correctly, using appropriate methods for different data types, and closing the scanner to prevent resource leaks. Careful error handling can also make your programs more resilient.
๐ง Part A: Vocabulary
Match each term with its correct definition:
| Term |
Definition |
| 1. Scanner |
A. A sequence of characters |
| 2. System.in |
B. Reads a floating-point number |
| 3. nextLine() |
C. An input stream from the keyboard |
| 4. nextDouble() |
D. A class used for reading input |
| 5. String |
E. Reads a line of text |
(Match the numbers 1-5 to the letters A-E)
โ๏ธ Part B: Fill in the Blanks
Fill in the blanks in the following paragraph using the words provided:
The Scanner class is part of the ________ library. To use it, you must first ________ it. You create a Scanner object by writing Scanner input = new Scanner(________);. To read an integer, you use the ________ method, and to read a line of text, you use ________.
(Words: System.in, import, nextInt(), java.util, nextLine())
๐ค Part C: Critical Thinking
Explain why it's important to close the Scanner object after you're finished using it. What potential problems can occur if you don't close it?