Java 核心包速查手冊：java.lang、util、net、io、text、sql、awt、swing 功能總覽

編輯：Java 綜合教學

Java 標準庫 (JDK) 提供 8 大核心包，覆蓋語言基礎、集合框架、網絡編程、IO 操作、格式化、數據庫、GUI 開發等領域。本文速查各包核心類/接口與典型用途。

類/接口	核心功能
Object	所有類根類，equals/hashCode/toString/clone/wait/notify
String/StringBuilder/StringBuffer	字符串處理
Math/StrictMath	數學運算
System/Runtime	系統屬性、環境變量、GC、執行外部進程
Thread/Runnable/ThreadLocal	多線程基礎
Class/Package/Module	反射、模塊系統
Throwable/Error/Exception	異常體系
Integer/Long/Double/Boolean/Character	基本類型包裝器，自動裝箱/拆箱
Enum/Annotation	枚舉、註解元編程
ProcessBuilder	進程構建
StackWalker	堆棧走查 (JDK 9+)

領域	核心類/接口
Collection 體系	List/Set/Queue/Deque → ArrayList/LinkedList/HashSet/TreeSet/PriorityQueue/ArrayDeque
Map 體系	Map → HashMap/LinkedHashMap/TreeMap/ConcurrentHashMap/Hashtable/Properties
工具類	Collections/Arrays/Objects/Optional/Date/Calendar/GregorianCalendar/UUID/Random/Scanner/Timer/TimerTask
併發	Executor/ExecutorService/Future/Callable/CompletableFuture/ForkJoinPool/CountDownLatch/CyclicBarrier/Semaphore/Phaser/ConcurrentHashMap/ConcurrentLinkedQueue/Atomic*/Lock/Condition
函數式	Function/Predicate/Consumer/Supplier/Stream/Collector (JDK 8+)
時間 (JDK 8+)	LocalDate/LocalTime/LocalDateTime/Instant/Duration/Period/ZoneId/ZonedDateTime/DateTimeFormatter

Socket API：Socket/ServerSocket/DatagramSocket/MulticastSocket (TCP/UDP)。
URL 處理：URL/URLEncoder/URLDecoder/URI/URLClassLoader/URLConnection/HttpURLConnection。
網絡接口：NetworkInterface/InetAddress/Inet4Address/Inet6Address/InterfaceAddress。
代理/協議：Proxy/ProxySelector/ResponseCache/CookieHandler/CookieManager。
NIO.2：AsynchronousSocketChannel/AsynchronousServerSocketChannel/CompletionHandler (JDK 7+)。

方向	字節流	字符流
輸入	InputStream → FileInputStream/ByteArrayInputStream/ObjectInputStream/DataInputStream/BufferedInputStream/PushbackInputStream/SequenceInputStream	Reader → FileReader/CharArrayReader/StringReader/BufferedReader/InputStreamReader/PushbackReader
輸出	OutputStream → FileOutputStream/ByteArrayOutputStream/ObjectOutputStream/DataOutputStream/BufferedOutputStream/PrintStream	Writer → FileWriter/CharArrayWriter/StringWriter/BufferedWriter/OutputStreamWriter/PrintWriter

文件操作：File/RandomAccessFile/FileDescriptor/FilePermission。
序列化：Serializable/Externalizable/ObjectInputStream/ObjectOutputStream/serialVersionUID。
NIO：FileChannel/ByteBuffer/MappedByteBuffer/Selector/Path/Files/Paths (JDK 7+)。

日期/數字/消息：SimpleDateFormat/DateFormat/NumberFormat/DecimalFormat/MessageFormat/ChoiceFormat。
排序/規則：Collator/RuleBasedCollator/CollationKey/BreakIterator (文本邊界分析)。
JDK 8+ 推薦：java.time.format.DateTimeFormatter (線程安全、不可變)。

核心接口：Connection/Statement/PreparedStatement/CallableStatement/ResultSet/ResultSetMetaData/DatabaseMetaData/ParameterMetaData。
數據源/連接池：DataSource/ConnectionPoolDataSource/PooledConnection (javax.sql)。
事務/保存點：Savepoint/TransactionIsolation。
行集：RowSet/JdbcRowSet/CachedRowSet/WebRowSet/JoinRowSet/FilteredRowSet。
JDBC 4.2+：大對象獲取、Ref/Cursor/Array/SQLXML 類型支持。

容器：Frame/Window/Dialog/Panel/Applet/ScrollPane/Container/Component。
佈局：FlowLayout/BorderLayout/GridLayout/GridBagLayout/CardLayout/BoxLayout。
事件：Event/ActionEvent/MouseEvent/KeyEvent/FocusEvent/WindowEvent/EventListener/Adapter。
圖形：Graphics/Graphics2D/Image/BufferedImage/Color/Font/Shape/Rectangle/Ellipse2D/Path2D。
打印：Printable/PrinterJob/PageFormat/Book/Pageable。

組件：JFrame/JDialog/JPanel/JButton/JLabel/JTextField/JTextArea/JComboBox/JList/JTable/JTree/JTabbedPane/JSplitPane/JScrollPane/JToolBar/JMenuBar/JPopupMenu/JFileChooser/JColorChooser/JOptionPane/JProgressBar/JSlider/JSpinner。
模型：TableModel/ListModel/TreeModel/ComboBoxModel/ButtonModel/Document/Action。
佈局：GroupLayout/SpringLayout/OverlayLayout/ViewportLayout。
線程：SwingUtilities.invokeLater/invokeAndWait (EDT 事件分發線程)。
Look&Feel：UIManager/LookAndFeel/Metal/Nimbus/Windows/Mac OS X 主題。