Static Nested Class是被声明为静态（static）的内部类，它可以不依赖于外部类实例被实例化。而通常的内部类需要在外部类实例化后才能实例化，其语法看起来挺诡异的，如下所示。
/** * 扑克类（一副扑克） * @author 骆昊 * */public class Poker { private static String[] suites = {"黑桃", "红桃", "草花", "方块"}; private static int[] faces = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13}; private Card[] cards; /** * 构造器 * */ public Poker() { cards = new Card[52]; for(int i = 0; i < suites.length; i++) { for(int j = 0; j < faces.length; j++) { cards[i * 13 + j] = new Card(suites[i], faces[j]); } } } /** * 洗牌 （随机乱序） * */ public void shuffle() { for(int i = 0, len = cards.length; i < len; i++) { int index = (int) (Math.random() * len); Card temp = cards[index]; cards[index] = cards[i]; cards[i] = temp; } } /** * 发牌 * @param index 发牌的位置 * */ public Card deal(int index) { return cards[index]; } /** * 卡片类（一张扑克） * [内部类] * @author 骆昊 * */ public class Card { private String suite; // 花色 private int face; // 点数 public Card(String suite, int face) { this.suite = suite; this.face = face; } @Override public String toString() { String faceStr = ""; switch(face) { case 1: faceStr = "A"; break; case 11: faceStr = "J"; break; case 12: faceStr = "Q"; break; case 13: faceStr = "K"; break; default: faceStr = String.valueOf(face); } return suite + faceStr; } }} |
测试代码：
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class PokerTest { public static void main(String[] args) { Poker poker = new Poker(); poker.shuffle(); // 洗牌 Poker.Card c1 = poker.deal(0); // 发第一张牌 // 对于非静态内部类Card // 只有通过其外部类Poker对象才能创建Card对象 Poker.Card c2 = poker.new Card("红心", 1); // 自己创建一张牌 System.out.println(c1); // 洗牌后的第一张 System.out.println(c2); // 打印: 红心A }} |