Text Processing Chapter 9 Quiz

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Questions and Answers

What is a wrapper class?

A class that cannot be modified

A class only for strings

A class that wraps around a primitive data type (correct)

A class for creating variables

Wrapper classes in Java are mutable.

False

What are primitive data types?

Data types that are not created from classes and do not have attributes or methods.

What does the character class do?

It is a wrapper class for the char data type that provides methods for testing and converting character data. Signup and view all the answers

The method boolean isDigit(char ch) returns true for characters other than digits.

False Signup and view all the answers

What does the method boolean isLetter(char ch) check?

It checks if the character is an alphabetic letter. Signup and view all the answers

What does the method boolean isSpaceChar(char ch) tell us?

It checks if the character is a space character. Signup and view all the answers

What is the purpose of the method char toLowerCase(char ch)?

It returns the lowercase equivalent of the character passed to it. Signup and view all the answers

What does the valueOf method do?

It converts a primitive data type to its string representation. Signup and view all the answers

The StringBuilder class allows its objects to be modified.

True Signup and view all the answers

What does the method trim() do?

Removes leading and trailing whitespace characters Signup and view all the answers

When tokenizing a string, it is unnecessary to trim it beforehand.

False Signup and view all the answers

What is autoboxing?

Java's process of automatically converting a primitive value into a wrapper class object. Signup and view all the answers

What is unboxing?

The process of converting a wrapper class object to a primitive type. Signup and view all the answers

What is a delimiter?

A character that separates tokens. Signup and view all the answers

What is the file extension used for a comma-separated value file?

.csv Signup and view all the answers

Study Notes

Wrapper Classes

Wrapper classes are classes that encapsulate primitive data types, allowing the creation of objects instead of just variables.
They provide methods to perform operations related to the encapsulated primitive type and are immutable.
Java defines wrapper classes for each primitive data type, including Byte, Double, Float, Integer, Long, and Short.

Primitive Data Types

Primitive data types are basic data types that are not objects and do not possess attributes or methods.
These types include byte, double, float, int, long, and short.

Character Class

The Character Class serves as a wrapper for the char data type and offers methods for character testing and conversion.

Character Testing Methods

isDigit(char ch): Checks if the character is a digit (0-9).
isLetter(char ch): Verifies if the character is an alphabetic letter.
isLetterOrDigit(char ch): Returns true for characters that are either digits or letters.
isLowerCase(char ch): Checks if the character is a lowercase letter.
isUpperCase(char ch): Checks if the character is an uppercase letter.
isSpaceChar(char ch): Identifies if the character is a space character.
isWhiteSpace(char ch): Identifies if the character is any whitespace character (space, tab, newline).

String Manipulation Methods

substring(int start): Extracts a substring from a specified starting index to the end of the string.
substring(int start, int end): Returns a substring from start to end (end is exclusive).
concat(String str): Combines the contents of the calling string with another string.
trim(): Eliminates leading and trailing whitespace characters.

String Search Methods

indexOf(char ch): Locates the first occurrence of a character within the string, returning its index or -1 if not found.
lastIndexOf(char ch): Finds the last occurrence of a character, searching from the end of the string.

String Comparison Methods

startsWith(String str): Verifies if the string begins with the specified prefix.
endsWith(String str): Confirms if the string ends with the specified suffix.
regionMatches(...): Compares specific regions of two strings for equality.

StringBuilder and StringBuffer

The StringBuilder class allows modification of string contents and provides additional methods compared to String.
StringBuffer methods are synchronized for thread safety, while StringBuilder methods are not.

Tokenization

Tokenizing is the act of breaking a string into components called tokens, often using the String class's split method.
The delimiter is a character that separates tokens.

Regular Expressions

Regular expressions specify patterns of characters and can be used to search for those patterns within strings and other text collections.

Autoboxing and Unboxing

Autoboxing is the automatic conversion of primitive values into their corresponding wrapper objects.
Unboxing is the reverse process, converting wrapper objects back into their primitive types.

Static Members and Constants

MIN_VALUE and MAX_VALUE are static final variables representing the minimum and maximum values for respective data types.

CSV File Format

Comma Separated Value (CSV) format is used when exporting data from Excel, where rows correspond to lines and cell values are delineated by commas.
Files saved in this format use the .csv extension.

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Description

Test your knowledge on Wrapper Classes as discussed in Chapter 9 of 'Text Processing and More about Wrapper Classes'. This quiz dives into the definitions, uses, and characteristics of wrapper classes in Java. Perfect for reinforcing your understanding of these essential programming concepts.