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Java Dictionary

Java Dictionary Index

[Setup] Java Development Environment	Setup instructions for installing, compiling, and running Java.
String.length() / charAt()	Gets the length of a string and retrieves a character at a specific position.
String.indexOf() / lastIndexOf() / contains()	Searches for a substring and checks its existence.
String.startsWith() / endsWith() / matches()	Checks prefix, suffix, and regular expression matching.
String.substring()	Extracts a portion of a string.
String.replace() / replaceAll() / replaceFirst()	Replaces parts of a string.
String.toUpperCase() / toLowerCase() / trim()	Converts case and removes whitespace.
String.split() / String.join()	Splits and joins strings.
String.equals() / equalsIgnoreCase() / compareTo()	Compares strings.
String.valueOf() / Integer.toString()	Converts between numbers and strings.
String.toCharArray() / String.copyValueOf()	Converts between a string and a character array.
new StringBuilder() / builder.append() / insert()	Mutable string operations for appending and inserting.
builder.reverse() / replace() / toString()	Reverses, replaces, and converts strings.
Arrays.sort() / Arrays.binarySearch()	Sorts an array and performs binary search.
Arrays.copyOf() / Arrays.copyOfRange() / Arrays.fill()	Copies and fills arrays.
Arrays.equals() / Arrays.toString() / Arrays.asList()	Compares arrays, converts to string, and converts to List.
new ArrayList<>() / list.add() / set() / get()	Creates a list, and adds, updates, and retrieves elements.
list.remove() / clear() / size() / isEmpty()	Removes elements, clears a list, and checks its size.
list.contains() / indexOf() / subList()	Searches within a list and retrieves a sublist.
Collections.sort() / Collections.shuffle() / Collections.reverse()	Sorts, shuffles, and reverses a list.
new HashMap<>() / map.put() / get() / getOrDefault()	Creates a map, and adds and retrieves entries.
map.remove() / containsKey() / containsValue() / size()	Removes entries and checks for key existence.
map.keySet() / values() / entrySet()	Retrieves keys, values, and entries from a map.
new HashSet<>() / set.add() / contains() / remove()	Creates a set, and adds, checks, and removes elements.
set.size() / isEmpty() / iterator()	Gets the size of a set and iterates over it.
new LinkedList<>() / queue.offer() / poll() / peek()	Operations on a queue.
new ArrayDeque<>() / deque.push() / pop()	Operations on a stack and double-ended queue.
collection.stream() / stream.filter() / map()	Creates a stream and filters or transforms its elements.
stream.collect() / toList()	Collects a stream into a collection.
stream.forEach() / reduce() / count()	Iterates over, aggregates, and counts stream elements.
stream.sorted() / distinct() / limit() / skip()	Sorts, removes duplicates, and limits stream elements.
stream.findFirst() / anyMatch() / allMatch() / noneMatch()	Searches and evaluates conditions on stream elements.
Optional.of() / isPresent() / orElse() / orElseThrow()	A null-safe wrapper class.
Integer.parseInt() / Double.parseDouble()	Converts a string to a numeric value.
Integer.MAX_VALUE / MIN_VALUE / Integer.toBinaryString()	Integer constants and radix conversion.
Math.abs() / max() / min() / round() / floor() / ceil()	Performs numerical calculations and rounding.
LocalDate.now() / of() / getYear() / getMonth()	Gets or creates a date.
LocalDateTime.now() / LocalTime.now()	Gets the current date, time, or datetime.
DateTimeFormatter.ofPattern() / date.format()	Formats and parses date and time values.
new Scanner() / scanner.nextLine() / nextInt()	Reads from standard input, strings, and numbers.
new BufferedReader() / reader.readLine()	Reads input with buffering.
Files.readString() / Files.readAllLines()	Reads the entire content of a file.
Files.writeString() / Files.write()	Writes content to a file.
Files.exists() / isFile() / isDirectory() / createDirectory()	Checks and creates files and directories.
Files.copy() / move() / list() / walk()	Copies, moves, and lists files.
Pattern.compile() / Matcher.matches() / find()	Compiles a regular expression and performs matching.
Matcher.replaceAll() / replaceFirst()	Replaces text using a regular expression.
try / catch / finally / throw	The basic syntax for exception handling.
try-with-resources / AutoCloseable	Automatically closes resources.
class / new / Constructor / this	Defines a class and creates an instance.
public / private / protected / static / final	Access modifiers, static members, and constants.
extends / super / @Override	Inheritance and method overriding.
interface / implements / abstract	Interfaces and abstract classes.
Objects.equals() / Objects.toString() / Objects.requireNonNull()	The Objects utility class.
Generics (<T>)	Defines classes and methods with type parameters.
Lambda Expressions / (x) -> x * 2	A concise syntax for anonymous functions.
Predicate / Function / Consumer / Supplier	Major functional interfaces.
enum	Defines and uses enumeration types.
record	An immutable data class.
new Thread() / thread.start() / Runnable	Creates and starts a thread.
ExecutorService / Executors.newFixedThreadPool()	Executes tasks using a thread pool.
CompletableFuture.supplyAsync() / thenApply() / join()	Asynchronous processing.
System.out.println() / System.err.println() / System.in	Standard output, error output, and standard input.
System.currentTimeMillis() / System.nanoTime() / System.exit()	Time measurement and process termination.
Objects.toString() / getClass() / instanceof	Checks the type of an object and converts it to a string.

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