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Questions and Answers
What is the purpose of getters and setters in Java?
Which command is used to compile Java source files?
What is an example of a non-numeric primitive cast in Java?
What is the purpose of the 'instanceof' operator in Java?
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Which of the following is NOT a primitive data type in Java?
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What is the main function of the 'java' command?
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How can you improve the readability of long numeric literals in Java?
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Which of these data types consumes the least memory in Java?
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What is the result of converting a float to an int in Java?
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What type of data can be stored in an Object reference in Java?
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Which component is responsible for generating documentation from Java source code?
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What is the purpose of packaging documentation in Java?
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Which of the following is an example of a hexadecimal literal?
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What is the primary purpose of using BufferedWriter?
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Which of the following is a characteristic of the Scanner class?
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What does deep copying involve when cloning objects?
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What happens when a method in Java recurses too deeply?
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In which scenario would you prefer using a Comparator over Comparable for sorting?
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How does Java handle numeric overflow in floating-point operations?
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What function does the 'continue' statement serve in loops?
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What is a common use of regular expressions in Java?
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Which method is used to prevent NullPointerExceptions during auto-unboxing?
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What is the role of 'default methods' in interfaces?
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Which statement correctly reflects the use of enums in singletons?
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What is the importance of manipulating paths in Java I/O?
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What is the purpose of the 'compareTo' method in Java?
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What is a primary advantage of using generics in Java?
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What does the diamond operator (<>) signify when declaring a generic type?
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Which of the following best describes method overloading?
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What is the purpose of a default method in Java interfaces?
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Which statement about inheritance is true?
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How do inner classes access the members of their outer classes?
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What is the significance of the ‘final’ keyword in Java?
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What does 'instanceof' allow you to do in Java?
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What is the role of stream operations in Java?
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Which of the following statements about threading and collections is correct?
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What is the key difference between a List and a Set?
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Which type of nested class does not have a reference to its enclosing class?
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When should you prefer using interface default methods?
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Study Notes
Getting Started with Java Language
- Create a simple Java program using
public class Main
. - The
main
method is the entry point for Java programs. -
System.out.println()
prints text to the console.
Type Conversion
- Cast numeric primitives between types, e.g.,
int
todouble
. - Numeric promotion automatically converts smaller types to larger types during arithmetic operations.
- Casting non-numeric primitives, such as
char
,boolean
, orString
, must be done explicitly. - Cast objects to specific subtypes using
(Type) object
. - Use
instanceof
to test if an object can be cast to a specific type prior to casting.
Getters and Setters
- Use setters to modify object attributes and getters to retrieve their values.
- Enforce value constraints by adding validation logic within setters.
- Improve code maintainability and readability by providing a standardized interface for accessing object attributes.
Reference Data Types
- Reference types store references to objects in memory.
- Use the
new
keyword to instantiate an object.
The Java Compiler - 'javac'
- Compile Java source code into bytecode using
javac
. - Use the
-d
option to specify the output directory for compiled classes. - Use the
-cp
option to specify the classpath for required libraries. - Use the
-source
flag to target a specific version of Java.
Documenting Java Code
- Use Javadoc comments to generate documentation for your code.
- Class documentation begins with
/**
and ends with*/
. - Method documentation includes descriptions, parameters, and return types.
- Include links to relevant documentation using the
{@link ...}
tag. - Place code snippets within documentation using the
{@code ...}
tag. - Document class fields using
/** ... */
above the field declaration. - Use inline code documentation for brief explanations within code blocks.
Command Line Argument Processing
- Use
args
array in themain
method to access command-line arguments. - Handle arguments individually or use libraries for easier parsing.
The Java Command - 'java' and 'javaw'
- Run Java applications using the
java
command. - Specify the fully qualified class name containing the
main
method. - Use
javaw
to run Java applications without a console window. - Include library dependencies using the
-cp
(classpath) option. - Use Java options like
-Xms
and-Xmx
to control memory allocation. - Escape spaces and special characters in command line arguments.
- Execute JAR files directly using the
java -jar
command. - Run Java applications by specifying the "main" class.
Literals
- Use underscores to improve readability of long numbers.
- Use hexadecimal, octal, and binary literals.
- Represent Boolean values with
true
andfalse
. - Use string literals enclosed in double quotes.
- Use
null
to represent the absence of a value. - Escape special characters within literals using backslashes.
- Represent characters using single quotes.
- Use decimal integer literals for whole numbers.
- Represent floating-point numbers using decimal points and exponents.
Primitive Data Types
- The
char
primitive type represents a single Unicode character. -
Primitive Types Cheatsheet:
-
boolean
- Representstrue
orfalse
values. -
byte
- Holds an 8-bit signed integer. -
short
- Holds a 16-bit signed integer. -
int
- Holds a 32-bit signed integer. -
long
- Holds a 64-bit signed integer. -
float
- Represents a 32-bit single-precision floating-point number. -
double
- Represents a 64-bit double-precision floating-point number.
-
- The
float
primitive type represents a 32-bit single-precision floating-point number. - The
int
primitive type represents a 32-bit signed integer. - Convert primitives to other types using casting or type conversion methods.
Generics
- Generics allow for type-safe code by accepting type parameters that can be specified at runtime.
-
? extends T
acts as an upper bound, indicating the type parameter can be T or any subtype of T. -
super T
acts as a lower bound, indicating the type parameter can be T or any supertype of T. - Generic methods are declared similar to generic classes but with type parameters within the method signature.
- To require multiple upper bounds on a type parameter, use the "extends A & B" syntax.
- The
Class.getGenericSuperclass()
andClass.getGenericInterfaces()
methods can be used to obtain the class that satisfies a generic parameter at runtime. - Generics improve code reusability and readability, reducing casting.
- To instantiate a generic type, specify actual types for the type parameters.
- A bounded generic class restricts type parameters to specific types or their subtypes.
- The
this
keyword can be used to refer to the declared generic type within its declaration. - Generic parameters can be bound to more than one type, each binding to a distinct type.
- Generics can help automatically cast objects to the correct type.
- The
instanceof
operator can be used with generics to check the runtime type of an object with respect to a generic type. - Implementing a generic interface or extending a generic class can be done in various ways, including specifying type parameters in the implementation or subclass declaration.
Classes and Objects
- Method overloading allows defining multiple methods with the same name but different parameter lists within a class.
- Method overriding occurs in inheritance when a subclass provides a different implementation of a method inherited from its superclass.
- Constructors are special methods called when a new object is created, initializing the object’s state.
- Static final fields can be initialized using a static initializer block, which executes once when the class is loaded.
- Object construction involves declaring a reference variable, creating an object using the
new
keyword followed by the constructor call, and assigning the object’s reference to the variable. - The simplest possible class contains a single method called
main
that serves as the entry point for the program. - An object member belongs to an instance of a class, while a static member belongs to the class itself.
Local Inner Class
- A local inner class is defined within a method or block of code and has access to local variables of the enclosing method.
Nested and Inner Classes
- A nested class is a class defined within another class.
- Static nested classes are associated with the outer class but are not directly associated with its instances.
- Non-static nested classes (inner classes) are associated with instances of the outer class and have access to all members (including private members) of the outer class.
- Anonymous inner classes are unnamed classes that can be used to implement interfaces or extend classes. They create an implementation on the fly.
- To create an instance of a non-static inner class from outside the outer class, an object of the outer class is needed.
- Method local inner classes are defined within a method and have access to local variables of the enclosing method.
- An inner class can access non-private members of the outer class directly, while private members are accessible through an object of the outer class.
The java.util.Objects Class
- The
Objects.nonNull()
method reference can be used in stream API to filter and process non-null elements in a stream. - The
Objects.isNull()
method can be used to check if an object is null, simplifying null checks and enhancing clarity.
Default Methods
- Default methods provide implementations for methods in interfaces, allowing for the extension of interfaces without breaking backward compatibility.
- Implementing classes can access overridden default methods from the interface.
- Default methods allow for the introduction of new functionalities to existing interfaces without requiring modifications to existing classes implementing the interface.
Packages
- Packages allow for organizing classes and interfaces into logical groups.
- Packages can be used to create classes with the same name without conflict.
- Using package-protected scope restricts access to classes and members to the same package.
Inheritance
- Inheritance enables creating new classes (subclasses) that inherit properties and behaviors from existing classes (superclasses).
- Abstract classes cannot be instantiated directly but can be inherited and their abstract methods must be implemented by concrete subclasses.
- The
final
keyword is used to prevent inheritance or method overriding. - The Liskov Substitution Principle states that subclasses should be able to replace their superclasses without altering the correctness of the program.
- Abstract classes and interfaces both promote code reuse and polymorphism, but classes implement interfaces and inherit from abstract classes.
- Abstract classes can have constructors, but these are only invoked when a concrete subclass is created.
- Static inheritance is a concept where static members of a subclass can be accessed through the subclass type.
- Programming to an interface encourages flexibility and promotes the use of polymorphism.
- Overriding enables subclasses to provide specialized implementations of methods inherited from superclasses.
- Variable shadowing occurs when a variable in a subclass has the same name as a variable in its superclass.
- Narrowing assigns a subclass reference to a superclass reference, while widening does the opposite.
- Static methods are not inherited.
Reference Types
- Reference types define the type of an object that can be assigned to a variable.
- Different reference types have different characteristics, such as immutable objects.
Console I/O
- The
Scanner
class is used to read user input from the console. - The
System.out.printf()
method can be used to format strings in console output. - Implementing basic command-line behavior involves parsing input and performing actions based on user commands.
Streams
- Streams provide a concise and powerful way to process sequences of data.
- Streams can be consumed by performing operations on the elements and generating a result.
- A frequency map can be created by collecting elements into a Map and counting their occurrences.
- Infinite streams can generate an unlimited number of elements.
- Streams can be collected into collections using the
collect()
method. - Streams can be used to implement mathematical functions, such as finding the sum or average of elements.
- The
flatMap()
operation is used to flatten streams of nested elements. - Parallel streams allow for parallel processing of data to improve performance.
- Streams can be created from various sources, such as arrays, collections, and files.
- The
statistics()
method provides statistical information about numerical streams. - An iterator can be converted to a stream using the
StreamSupport.stream()
method. - An
IntStream
can be used to iterate over indexes in a stream. - Streams can be concatenated using the
concat()
method. - The
reduce()
operation is used to combine elements in a stream into a single value. - It is possible to preserve initial values after mapping a stream of Map.Entry.
- An
IntStream
can be converted to a String using themapToObj
andcollect
methods. - The
findFirst()
method finds the first element in a stream that matches a predicate. - Streams and method references can be used to write self-documenting processes.
- A Stream of Optional can be converted to a Stream of values.
- It is possible to obtain a slice of a stream by using
limit()
andskip()
methods. - A Map can be created based on a stream using the
collect()
method. - A stream can be joined to a single String using the
Collectors.joining()
method. -
sorted()
method can be used to sort a stream based on the elements. - Streams of primitives offer optimized operations for primitive data types.
- Stream operations can be classified into categories such as intermediate and terminal operations.
- The results of a stream can be collected into an array using the
toArray()
method. - Random strings can be generated using Streams and the
Random
class.
InputStreams and OutputStreams
- Streams should be closed after use to release resources.
- The
InputStream
can be read into a String using theBufferedReader
class. - Input/Output streams can be wrapped to provide additional functionality, such as buffering.
- The
DataInputStream
class can be used to read data in a stream. - The
OutputStream
can be used to write bytes to a file or other output destination. - An input stream can be copied to an output stream using the
transferTo()
method.
Readers and Writers
- The
BufferedReader
class provides buffered reading from a character stream. - The
StringWriter
class allows for writing strings to a memory-based character stream.
Preferences
- Preferences allow for storing application-specific data, such as user settings.
- Event listeners can be added to track changes in preferences.
- Sub-nodes of preferences can be accessed to organize data hierarchically.
- Preferences can be coordinated across multiple application instances.
- Preferences can be exported and imported.
- Event listeners can be removed to stop receiving notifications.
- Preferences values can be retrieved using the
get()
method. - Preferences values can be set using the
put()
method.
Collection Factory Methods
- Factory methods provide a convenient way to create collections without explicitly specifying the implementation type.
- Factory methods are available for Lists, Sets, and Maps.
Alternative Collections
- Guava, Apache Collections, and Eclipse Collections provide alternative collections that offer enhanced functionality and performance.
- Multimaps allow for mapping keys to multiple values.
- HashBags, HashMultisets, and similar collections provide functionalities for managing collections of objects while maintaining counts for duplicate elements.
- Collections can be compared for equality based on their elements.
Concurrent Collections
- Concurrent collections are thread-safe, enabling safe access and modification by multiple threads.
- Insertion into a
ConcurrentHashMap
happens concurrently, minimizing locking overhead. - Concurrent collections provide a way to manage data in multithreaded environments.
Choosing Collections
- There are different collections each with different characteristics to be considered when making a choice.
- A flowchart can be used to help choose the best collections based on specific use cases.
super Keyword
- The
super
keyword refers to the superclass. -
super
can invoke constructors of the superclass or access inherited members with different implementations.
Serialization
- Serialization allows for converting objects into byte streams for storage or transmission.
- Basic serialization involves marking a class as Serializable and letting the default serialization mechanism handle the process.
- Custom serialization enables controlling how an object is serialized and deserialized by implementing the
writeObject
andreadObject
methods. - Serialization can handle versioning and version compatibility using the
serialVersionUID
field. - Libraries like Gson and Jackson provide tools for serializing and deserializing objects to and from JSON format.
Optional
- The
Optional
class represents a container that may or may not hold a value. - The
isPresent()
method can be used to check if the optional object contains a value. - The
get()
method retrieves the value if present, or throws an exception if the optional is empty. - The
orElse(T other)
method returns the value if present, or provides a default value. - The
orElseThrow(Supplier<? extends X> exceptionSupplier)
method throws an exception if the optional is empty. - The
orElseGet(Supplier<? extends T> other)
method lazily provides a default value if the optional is empty. - The
filter(Predicate<? super T> predicate)
method acts like a filter on the optional based on the predicate condition. - Optional classes can be used to hold primitive numeric types.
- The
ifPresent(Consumer<? super T> consumer)
method executes the consumer action only if a value is present. - The
flatMap(Function<? super T, Optional<U>> mapper)
method allows applying a function that returns an Optional object.
Object References
- Object references are used as method parameters to pass objects by reference, enabling modification of the original object.
Exceptions and Exception Handling
- Exceptions represent error conditions encountered during program execution.
- The
try-catch
block is used to handle exceptions. - The
try-with-resources
statement ensures resources are properly closed, even if an exception occurs. - Custom exceptions can be defined to represent specific error conditions.
- The
InterruptedException
exception can be caught when a thread’s execution is interrupted. - The
return
statements in atry-catch
block can be placed in different locations based on the handling logic. - The Java exception hierarchy categorizes exceptions into checked and unchecked exceptions.
- Stacktraces provide information about the chain of method calls leading to an exception.
- The
throw
keyword is used to explicitly throw an exception. - Try-finally and try-catch-finally blocks are used to ensure specific code execution, like resource cleanup, regardless of exception occurrence.
- The
throws
clause in a method declaration indicates which exceptions a method might throw.
Calendar and its Subclasses
- The
Calendar
class represents a calendar system. -
Calendar
objects can be created usinggetInstance()
orgetCalendar()
methods. - Calendar fields can be increased or decreased, such as adding days or months.
- Subtracting calendars allows calculating time differences.
- The
get()
method can be used to get the AM/PM indicator for a given time.
The static Keyword
- The
static
keyword indicates a class-level member that belongs to the class itself and not to its instances. - Attempts to access a non-static member from a static context will result in a compilation error.
- The
static
modifier can be used to declare fields as constants.
Properties Class
- The
Properties
class is used to manage key-value pairs from property files. - Properties can be loaded from a property file using the
load()
method. - Properties can be saved as XML using the
storeToXML()
method. - Trailing whitespace in property files can cause issues, requiring careful handling.
Lambda Expressions
- Lambda expressions are anonymous functions that can be used to implement functional interfaces.
- Lambda expressions have a concise syntax and allow for passing behavior as arguments.
- Lambda expressions can be used to implement a single abstract method of a functional interface.
- Method references provide a concise way to refer to existing methods in a lambda expression.
- Lambda expressions can be used to override multiple interface methods.
- Lambda expressions are commonly used in event handling scenarios such as event listeners.
- Lambda expressions in Java are effectively closures, allowing them to access variables from the enclosing scope.
- Lambda expressions are typically smaller in memory footprint compared to anonymous inner classes.
- Custom functional interfaces can be defined and used with Lambda expressions.
- Lambda expressions can be used to convert code written in the traditional style into a more functional style.
- The
return
keyword within a lambda expression returns from the lambda, not the outer method. - Lambda expressions enable using the “execute-around” pattern by providing a function that encapsulates the core logic.
- Lambda expressions with predicates can be used to find specific elements within a collection.
Basic Control Structures
- The
switch
statement allows for multiple case branches based on a value. - The
do...while
loop executes a block of code at least once and then continues iteration based on a condition. - The
for each
loop iterates over elements of a collection. - The
continue
statement skips the rest of the current iteration of a loop. - The
if/else if/else
block executes code conditionally based on Boolean expressions. - The
for
loop executes a code block repeatedly based on an initialization expression, a Boolean condition, and an update expression. - The ternary operator allows for a concise conditional expression that evaluates to one of two values.
Chapter 74: Control Flow
- Break statement stops execution of the current loop and passes control to the statement following the loop.
- While loop allows repetitive execution of a block of code as long as a certain condition is true.
- If/Else statement provides a way to execute code based on certain logical conditions.
- Nested break/continue can be used within loops to control the flow of execution.
Chapter 75: BufferedWriter
- BufferedWriter allows writing lines of text to a file efficiently.
Chapter 76: New File I/O
- Paths represent file and directory locations in the file system.
- Paths can be manipulated using methods like resolve, getParent, and getFileName to navigate the file system.
- Information about a path can be retrieved using methods like isAbsolute, getName, and getFileSystem.
- Methods of the FileSystems class provide access to file system details, including root directories and supported file systems.
- Reading files involves reading data from a file as bytes or characters.
- Writing files involves creating or modifying a file and writing data to it.
Chapter 77: File I/O
- Java 7 NIO (java.nio.file.Path) offers enhanced file system capabilities and replaces java.io.File in certain contexts.
- Java provides methods for reading images stored in files.
- FileInputStream and FileOutputStream are used for reading and writing raw bytes to files.
- Data can be read into a byte array to process it in memory.
- Channels provide a more efficient way to copy files by directly accessing underlying resources.
- Stream and Writer/Reader APIs are used for working with data streams but with different levels of abstraction.
- Scanner class assists in reading data from files using different delimiters and data types.
- InputStream and OutputStream can be used when copying files from one location to another.
- Binary files can be read using techniques that handle byte-level data.
- Channels and Buffers provide efficient means for reading and writing data in blocks.
- Directories can be added to the file system programmatically.
- Standard output and error can be either blocked or redirected for specific purposes.
- An entire file can be read into memory all at once in some cases, depending on the file size and memory availability.
- Locking mechanisms prevent simultaneous modifications to files by multiple processes.
- BufferedInputStream improves file reading performance by buffering data in memory.
- Java provides methods for iterating over directories and printing subdirectories.
- Channels and Buffers are used to efficiently write data to files in blocks.
- PrintStream provides a convenient way to write data to files in a formatted manner.
- Iterating over a directory and filtering files based on specific extensions is commonly used.
- ZIP files can be accessed programmatically for reading their contents.
Chapter 78: Scanner
- Scanner provides a versatile way to read input data from various sources, including the command line and files.
- It uses regular expressions to define how data is parsed and extracted.
- Scanner allows using custom delimiters for defining how data is separated into tokens.
- System input can be read using a Scanner object.
- File input can be read using a Scanner object that reads from a specific file.
- The full input stream as a string can be read using Scanner.
- Careful closure of Scanner objects is important to release resources.
- Integers can be read from the command line using Scanner.
Chapter 79: Interfaces
- Multiple interfaces can be implemented by a single class using the implements keyword.
- Interfaces declare a set of methods and constants that implementing classes must provide.
- Interfaces can extend other interfaces to inherit their methods and constants.
- Interfaces are crucial for promoting code reusability, polymorphism, and decoupling.
- Java 8 introduced default methods in interfaces allowing specific functionality.
- Interfaces can contain modifiers like public, abstract, and static to control method access and behavior.
- Generics can work with interfaces to provide flexible and type-safe implementations.
- Interfaces can strengthen bounded type parameters by imposing additional constraints on types.
- Interfaces can be implemented within abstract classes, allowing abstract classes to inherit interface methods.
Chapter 80: Regular Expressions
- Regular expressions (regex) provide powerful patterns for searching and manipulating text.
- Capture groups within regex allow extracting specific parts of matched strings.
- Flags can be used when compiling a regex pattern to modify its behavior.
- Escape characters are used to represent special characters in regex expressions.
- Regex can be used to test if a string does not match a given pattern.
- Regex literals are a convenient notation for expressing regex patterns directly within code.
- Matching a backslash requires special handling due to its use in both strings and regex expressions.
Chapter 81: Comparable and Comparator
- Comparable interface allows objects to be compared using their natural ordering.
- Comparator interface allows objects to be compared using a custom ordering rule.
- Lists can be sorted using either Comparable or Comparator based on the desired ordering.
- compareTo and compare methods are responsible for comparing objects and determining their relative order.
- Natural sorting is based on the Comparable interface, while explicit sorting requires a Comparator.
- The comparing method provides a convenient way to create a Comparator using a lambda function.
- Map entries can be sorted based on various criteria using a Comparator.
Chapter 82: Java Floating Point Operations
- Comparing floating-point numbers requires using the
equals
method or tolerance for imprecision. - Overflow and underflow can occur when floating-point values exceed their representable range.
- Formatting floating-point values allows controlling their display precision and format.
- Java's floating-point operations adhere to the IEEE 754 specification which establishes standard rules.
Chapter 83: Currency and Money
- Java provides support for working with currencies using the Currency class.
- Custom currencies can be defined and managed using Currency.
Chapter 84: Object Cloning
- Deep copy creates an independent copy of an object, including its nested objects.
- Copy factory is a dedicated class that creates copies of objects.
- Copy constructors create copies of objects during initialization.
- Cloning can be achieved by implementing the Cloneable interface.
- Shallow copy creates a copy that shares references to the same nested objects.
Chapter 85: Recursion
- Recursion involves a function calling itself to solve a problem by breaking it down into smaller, similar subproblems.
- Deep recursion can lead to stack overflow due to excessively deep call stacks.
- Different types of recursion include linear, binary, and tail recursion.
- Fibonacci series is a classic example demonstrated using recursion.
- When facing stack overflow, recursion can often be replaced with iterative solutions.
- Recursion can be used to perform calculations like finding the nth power of a number.
- Traversal of tree data structures is commonly implemented using recursion.
- Reversing a string can be done using recursive techniques.
- Sum of integers from 1 to n can be efficiently calculated using recursion.
Chapter 86: Converting to and from Strings
- Converting from a String to other datatypes requires methods like parseInt, parseDouble, etc.
- Conversion between Strings and bytes involves using the
getBytes()
andnew String(bytes)
methods. - Base64 encoding and decoding convert data into a printable format.
- Converting other datatypes to String involves using String's
valueOf()
method ortoString()
methods in other classes. - Converting an InputStream to a String is done by reading the stream's contents and converting the bytes to a string.
Chapter 87: Random Number Generation
- Java uses pseudo-random number generators to produce sequences that appear random.
- Random numbers within a specific range can be generated using the Random object.
- Cryptographically secure pseudo-random numbers are suitable for applications requiring higher security.
- Generating random numbers with a specified seed allows producing repeatable sequences.
- Selecting random numbers without duplicates is useful in certain scenarios.
- Apache Commons Lang3 library provides additional random number generation utilities.
Chapter 88: Singletons
- Singletons are classes that ensure only one instance of themselves is created.
- Enum singleton provides a simple and thread-safe way to implement a singleton pattern.
- Eager initialization creates the singleton instance immediately on class loading.
- Thread-safe lazy initialization using a holder class ensures the singleton is created only when needed.
- Double-checked locking aims to provide thread-safe lazy initialization, but it might have issues in some cases.
- Extending a singleton pattern can pose challenges due to the single instance constraint.
Chapter 89: Autoboxing
- Autoboxing refers to the automatic conversion from primitive types to their corresponding wrapper classes.
- int and Integer can be used interchangeably due to autoboxing/unboxing, but it comes at the cost of performance.
- Auto-unboxing can lead to NullPointerException if an unboxed value is null.
- Boolean in if statements automatically unboxes its value.
- When working with collections or methods accepting objects, using the wrapper classes is necessary.
- There are overhead costs associated with autoboxing due to object creation and type conversions.
Chapter 90: 2D Graphics in Java
- The
Graphics2D
class in Java provides methods for drawing shapes, lines, text, and managing colors. - Examples illustrate how to draw and fill rectangles and ovals.
Chapter 91: JAXB
- JAXB (Java Architecture for XML Binding) is a framework for mapping Java objects to XML documents and vice versa.
- Unmarshalling reads an XML file and creates corresponding Java objects.
- Marshalling takes Java objects and generates XML representations.
- Manual field/property mapping provides precise control over XML serialization and deserialization.
- XML namespaces can be bound to specific Java classes for serialization and deserialization.
- XmlAdapter transforms data during serialization and deserialization.
- XmlAdapter can be used to customize the XML format, for example, trimming strings.
- Automatic field/property mapping simplifies the process using annotations like
@XmlAccessorType
. - XmlAdapter instances can be reused to handle existing data structures.
Chapter 92: Class - Java Reflection
- Java Reflection is a powerful mechanism for inspecting and manipulating code at runtime.
- The
getClass()
method of theObject
class returns the class of an object.
Chapter 93: Networking
- Various types of networking protocols exist, each offering different communication methods.
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