Java StringBuilder Class Flashcards

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Questions and Answers

What is a Java String?

An interface for character sequences

A sequence of characters

A mutable class for creating characters

An immutable class that represents a sequence of characters (correct)

The java.lang.String class implements the Serializable, Comparable, and CharSequence interfaces.

True

What does the CharSequence interface represent?

The sequence of characters

In Java, a String is mutable.

False Signup and view all the answers

What is a Java String literal?

A sequence created by using double quotes Signup and view all the answers

What does the NEW keyword do in Java?

Creates two objects and one reference variable Signup and view all the answers

What are Java String references used for?

To store various attributes like username, password, etc Signup and view all the answers

String objects in Java are mutable.

False Signup and view all the answers

What is the purpose of the StringBuilder class?

To create mutable strings Signup and view all the answers

What does the StringBuilder append() method do?

Concatenates the given argument with this String Signup and view all the answers

What does the StringBuilder insert() method do?

Inserts the given string at the given position Signup and view all the answers

What does the StringBuilder replace() method do?

Replaces the given string from the specified beginIndex and endIndex Signup and view all the answers

What is the function of the StringBuilder delete() method?

Deletes the string from the specified beginIndex and endIndex Signup and view all the answers

What does the StringBuilder reverse() method do?

Reverses the current string Signup and view all the answers

What does the StringBuilder capacity() method return?

Returns the current capacity of the Builder Signup and view all the answers

What is the purpose of the StringBuilder ensureCapacity() method?

Ensures that the given capacity is the minimum to the current capacity Signup and view all the answers

What does the StringBuilder getChars() method do?

Copies the characters starting at the given index Signup and view all the answers

Study Notes

Java Strings Overview

Java String Class: Provides various methods for string operations, including compare(), concat(), equals(), split(), length(), replace(), compareTo(), intern(), and substring.
Immutability: Java Strings are immutable; modifications create new instances instead of altering the existing one.
Java String Literals: Created using double quotes, representing a fixed sequence of characters.

String and Character Representation

String Object: In Java, a string is an object representing a sequence of characters.
CharSequence Interface: Represents a sequence of characters; implemented by String and StringBuilder classes, allowing string creation through these classes.

String Objects and Usage

String References: Store attributes like usernames and passwords, playing a crucial role in application programming.
Immutable Strings: String objects cannot be modified post-creation, categorized as unmodifiable.

StringBuilder Class

Mutable Strings: StringBuilder class allows creation of mutable strings, differing from StringBuffer by being non-synchronized.
Key Methods:
- append(): Concatenates a specified argument to the current string.
- insert(): Inserts a specified string at a specified position.
- replace(): Replaces a substring defined by beginIndex and endIndex with a new string.
- delete(): Removes characters defined by beginIndex and endIndex.
- reverse(): Reverses the characters in the current string.
- capacity(): Returns the current capacity of the StringBuilder.
- ensureCapacity(): Ensures that the StringBuilder's capacity is at least a specified minimum.
- getChars(): Copies characters starting from a specified index into a given destination array.

Memory Management

NEW Keyword: When using the NEW keyword to create Strings, two objects plus one reference variable are generated.

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Description

Test your knowledge on the Java StringBuilder class with these flashcards. Learn about key concepts such as the Java String class, CharSequence interface, and various string operations. Perfect for students looking to solidify their understanding of string handling in Java.