Java’s Standard Library is vast and covers many areas of functionality that make Java a powerful and versatile language.
| Library | Purpose | Key Classes | Description |
|---|---|---|---|
| java.lang | Core classes for basic functionality | String, Math, Object, Thread, System | Provides fundamental classes automatically imported into every Java program. Includes essential types like String, basic math, and system I/O. |
| java.util | Utility classes for data structures, collections, and dates | ArrayList, HashMap, HashSet, Date, Scanner | Contains classes for working with data collections (like lists and maps) and utility classes like Scanner for input and Date for date handling. |
| java.io | Input and output operations (file handling, streams) | File, BufferedReader, FileInputStream | Handles reading/writing data to/from files and streams. Includes character and byte streams for file I/O operations. |
| java.nio | More efficient I/O operations, buffer management | Path, Files, ByteBuffer, FileChannel | Provides non-blocking I/O operations, for handling files and network communication with better performance using buffers and channels. |
| java.net | Networking classes for communication over networks | Socket, ServerSocket, URL, HttpURLConnection | Facilitates network communication, providing classes for working with sockets, URLs, and making HTTP requests. |
| java.sql | Database connectivity through JDBC | Connection, Statement, ResultSet, DriverManager | Used for connecting to relational databases and executing SQL queries. |
| java.time | Date and time handling (modern API) | LocalDate, LocalTime, Instant, Duration | A modern API for working with date and time. It replaces older Date and Calendar classes and is immutable and thread-safe. |
| java.util.concurrent | Utilities for multithreading and concurrency | ExecutorService, CountDownLatch, ConcurrentHashMap | Provides classes for managing concurrent tasks, synchronization, and thread-safe data structures. |
| javax.swing | GUI components for desktop applications | JFrame, JButton, JLabel, JPanel | Enables building graphical user interfaces (GUIs) for desktop applications. Includes components for buttons, labels, windows, and containers. |
| java.security | Security-related utilities | MessageDigest, KeyPair, SecureRandom, Signature | Provides cryptographic operations, secure random numbers, and digital signatures. Essential for encryption and secure communication. |
| java.rmi | Remote Method Invocation for distributed computing | Remote, Naming, Registry | Allows invoking methods on objects running on different JVMs (remote communication). |
| javafx (optional) | Rich desktop UI framework (separate from JDK in newer versions) | Stage, Scene, Button, Label | A modern GUI framework for building cross-platform desktop applications with advanced features like animations and effects. |
| java.util.zip | Compression utilities (zip files) | ZipInputStream, ZipOutputStream, GZIPInputStream | For working with compressed files (e.g., .zip and .gzip formats) for reading and writing data in compressed formats. |
