For better or worse, Java also allows implementation inheritance.<\/p>\n\n\n\n
- \n
- Subclasses can inherit signatures AND implementation.<\/li>\n<\/ul>\n\n\n\n
Use the default keyword to specify a method that subclasses should inherit from an interface.<\/p>\n\n\n\n
- \n
- Example: Let's add a default print() method to List61B.java\u00a0<\/li>\n<\/ul>\n\n\n\n
\u4e3a\u4e86\u4e3e\u4f8b\u8bf4\u660e\u4e3a\u4ec0\u4e48\u6211\u4eec\u9700\u8981`default`\u5173\u952e\u5b57\uff0c\u9996\u5148\u5047\u8bbe\u6211\u4eec\u8bd5\u56fe\u50cf\u4f60\u5929\u771f\u5730\u90a3\u6837\u5b9a\u4e49\u4e00\u4e2a`print`\u65b9\u6cd5\uff0c\u597d\u5427\uff0c\u6211\u8981\u8bf4\u6253\u5370\u51fa\u6574\u4e2a\u5217\u8868\uff0c\u7136\u540e\u6211\u4eec\u5c1d\u8bd5\u7f16\u5199\u4e00\u4e9b\u4ee3\u7801\uff0c\u4f46\u5982\u679c\u4f60\u4ed4\u7ec6\u770b\uff0c\u8fd9\u91cc\u4f1a\u63d0\u793a\u201c\u63a5\u53e3\u65b9\u6cd5\u4e0d\u80fd\u6709\u4e3b\u4f53\u201d\uff0c\u5982\u679c\u6ca1\u6709`default`\u5173\u952e\u5b57\u7684\u8bdd\uff0c\u6211\u4e0d\u80fd\u8fd9\u6837\u505a\u3002\u6240\u4ee5\u73b0\u5728\u6211\u4eec\u53ef\u4ee5\u7f16\u5199\u4e00\u4e2a`print`\u65b9\u6cd5\uff0c\u5c3d\u7ba1\u8fd9\u53ef\u80fd\u770b\u8d77\u6765\u6709\u70b9\u5947\u602a\uff0c\u6bd4\u5982`List61b`\uff0c\u6211\u4eec\u4e0d\u77e5\u9053\u8fd9\u662f\u4e00\u4e2a`ArrayList`\u8fd8\u662f\u4e00\u4e2a\u94fe\u8868\uff0c\u4e8b\u5b9e\u4e0a\u6211\u4eec\u6ca1\u6709\u4efb\u4f55\u5b9e\u4f8b\u53d8\u91cf\uff0c\u6240\u4ee5\u7f16\u5199\u4e00\u4e2a\u6253\u5370\u65b9\u6cd5\u4f3c\u4e4e\u6709\u70b9\u68d8\u624b\uff0c\u4f46\u662f\u6211\u4eec\u6709\u6240\u6709\u8fd9\u4e9b\u65b9\u6cd5\u53ef\u4ee5\u5229\u7528\uff0c\u56e0\u4e3a\u4efb\u4f55\u5b9e\u73b0\u8fd9\u4e2a\u63a5\u53e3\u7684\u7c7b\u4e5f\u5fc5\u987b\u5b9e\u73b0\u8fd9\u4e9b\u65b9\u6cd5\uff0c\u8fd9\u662f\u5fc5\u9700\u7684\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u53ef\u4ee5\u7b80\u5355\u5730\u4f7f\u7528\u4f8b\u5982\u6211\u4eec\u7684`size`\u548c`get`\u65b9\u6cd5\uff0c\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\u505a\uff1a\u5bf9\u4e8e`i = 0; i < size(); i++`\uff0c\u8fd9\u91cc\u7684`size`\u662f\u6307\u5b9e\u73b0\u7c7b\u4e2d\u7f16\u5199\u7684\u65b9\u6cd5\uff0c\u73b0\u5728\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7`get(i)`\u6253\u5370\u51fa\u9879\u76ee\uff0c\u4e3a\u4e86\u7f8e\u89c2\u539f\u56e0\uff0c\u6211\u4f1a\u6dfb\u52a0\u4e00\u4e2a\u7a7a\u683c\uff0c\u6700\u540e\u4e3a\u4e86\u7f8e\u89c2\u539f\u56e0\uff0c\u6211\u4eec\u8fd8\u4f1a\u6dfb\u52a0\u4e00\u4e2a\u6362\u884c\u7b26\uff0c\u73b0\u5728\u5982\u679c\u6211\u4eec\u8fdb\u5165\u6f14\u793a\u5e76\u8fd0\u884c\u5b83\uff0c\u6211\u4eec\u4f1a\u5f97\u5230\u5217\u8868\u7684\u6253\u5370\u8f93\u51fa\uff0c\u5373\u4f7f`SList`\u7c7b\u672c\u8eab\u6ca1\u6709\u6307\u5b9a\u6253\u5370\u65b9\u6cd5\uff0c\u6240\u4ee5\u5982\u679c\u6211\u6309Ctrl+F\u641c\u7d22`print`\uff0c\u8fd9\u91cc\u6ca1\u6709\u5b9a\u4e49\u7684\u6253\u5370\u65b9\u6cd5\uff0c\u5c31\u662f\u8fd9\u6837\uff0c\u8fd9\u662f\u6211\u4eec\u5c06\u5728\u4e0b\u4e00\u4e2a\u89c6\u9891\u4e2d\u8981\u505a\u7684\u4e8b\u60c5\uff0c\u6240\u4ee5\u8fd9\u4e2a\u6253\u5370\u65b9\u6cd5\uff0c\u4e3a\u4e86\u8bf4\u670d\u4f60\u771f\u7684\u662f`List61b`\u7c7b\u5728\u6267\u884c\u6253\u5370\uff0c\u5982\u679c\u6211\u4eec\u4f7f\u7528\u8c03\u8bd5\u5668\u5e76\u8fd0\u884c\u5230\u8fd9\u4e00\u884c\uff0c\u7136\u540e\u5355\u6b65\u6267\u884c\uff0c\u6211\u4eec\u4f1a\u770b\u5230\u6211\u4eec\u73b0\u5728\u6b63\u5728\u8fd0\u884c\u63a5\u53e3\u5185\u90e8\u7684\u4ee3\u7801\uff0c\u8fd9\u5bf9Java\u6765\u8bf4\u5176\u5b9e\u662f\u4e00\u4e2a\u76f8\u5f53\u65b0\u7684\u7279\u6027\uff0c\u5728Java 8\u53d1\u5e03\u4e4b\u524d\u662f\u4e0d\u53ef\u80fd\u7684\uff0cJava 8\u53d1\u5e03\u4e8e\u5927\u7ea62015\u5e74\u62162016\u5e74\uff0c\u6240\u4ee5\u8fd9\u662f\u4e00\u4e2a\u76f8\u5bf9\u65b0\u7684Java\u7279\u6027\uff0c\u6709\u70b9\u4e89\u8bae\uff0c\u4f46\u8981\u77e5\u9053\u5b83\u5b58\u5728\uff0c\u867d\u7136\u6211\u53ef\u80fd\u4f1a\u65f6\u4e0d\u65f6\u62b1\u6028\u5b9e\u73b0\u7ee7\u627f\u7684\u95ee\u9898\uff0c\u8fd9\u91cc\u662f\u521a\u521a\u7f16\u5199\u7684\u65b9\u6cd5\uff0c\u4e3b\u8981\u7684\u533a\u522b\u662f\u6240\u6709\u8fd9\u4e9b\u5176\u4ed6\u65b9\u6cd5\u4f60\u53ea\u7ee7\u627f\u5b83\u4eec\u7684\u7b7e\u540d\uff0c\u8fd9\u662f\u63a5\u53e3\u7ee7\u627f\uff0c\u800c\u8fd9\u662f\u5b9e\u73b0\u7ee7\u627f\uff0c\u56e0\u4e3a\u6211\u4eec\u5f97\u5230\u4e86\u5b9e\u73b0\u3002<\/p>\n\n\n\n
\u4e8b\u5b9e\u4e0a \u5305\u542b\u8fd9\u51e0\u4e2a\u6587\u4ef6<\/p>\n\n\n\n
- \n
- SLList.java<\/li>\n\n\n\n
- DMSDemo.java<\/li>\n\n\n\n
- List61B.java<\/li>\n\n\n\n
- IsADemo.java<\/li>\n\n\n\n
- AList.java<\/li>\n\n\n\n
- WordUtils.java<\/li>\n<\/ol>\n\n\n\n
![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246237-\u5c4f\u5e55\u622a\u56fe-2024-11-10-145300-1024x570.png\")
<\/figure>\n<\/div>\n\n\n\u6211\u6709\u4e00\u4e2a\u8c1c\u9898\u7ed9\u4f60\uff0c\u4ee5\u6fc0\u52b1\u6211\u4eec\u7684\u4e0b\u4e00\u4e2a\u89c6\u9891\uff0c\u90a3\u5c31\u662f\u4f60\u8ba4\u4e3a
print<\/code>\u65b9\u6cd5\u5bf9ArrayList<\/code>\u548cSList<\/code>\u90fd\u9ad8\u6548\u5417\uff1f\u8fd8\u662f\u53ea\u5bf9\u5176\u4e2d\u4e00\u4e2a\u9ad8\u6548\uff0c\u6216\u8005\u5b9e\u9645\u4e0a\u5bf9\u4e24\u8005\u90fd\u4e0d\u9ad8\u6548\uff1f\u4e4d\u4e00\u770b\uff0c\u8fd9\u6bb5\u4ee3\u7801\u770b\u8d77\u6765\u6548\u7387\u5f88\u9ad8\uff0c\u5b83\u53ea\u662f\u904d\u5386\u6bcf\u4e2a\u9879\u76ee\u5e76\u6253\u5370\u51fa\u6765\uff0c\u4f46\u4ed4\u7ec6\u60f3\u60f3size<\/code>\u548cget<\/code>\u65b9\u6cd5\u5728ArrayList<\/code>\u548cSList<\/code>\u4e2d\u4f1a\u662f\u4ec0\u4e48\u6837\u7684\uff0c\u6211\u4f1a\u5728\u8fd9\u91cc\u505c\u987f\u4e00\u4e0b\uff0c\u8ba9\u4f60\u601d\u8003\u4e00\u4e0b\u3002\u7ed3\u679c\u8bc1\u660e\uff0c\u867d\u7136size<\/code>\u65b9\u6cd5\u5bf9\u8fd9\u4e24\u4e2a\u7c7b\u6765\u8bf4\u90fd\u975e\u5e38\u5feb\uff0c\u4f46\u4eceSList<\/code>\u7684\u4e2d\u95f4\u83b7\u53d6\u9879\u76ee\u4f1a\u5f88\u6162\uff0c\u6240\u4ee5\u6211\u4eec\u9884\u8ba1\u5b83\u5bf9ArrayList<\/code>\u662f\u9ad8\u6548\u7684\uff0c\u800c\u5bf9SList<\/code>\u5219\u662f\u4f4e\u6548\u7684\uff0c\u4ec5\u4ec5\u662f\u56e0\u4e3aArrayList<\/code>\u7684get<\/code>\u65b9\u6cd5\u975e\u5e38\u5feb\uff0c\u53ea\u9700\u4ece\u6570\u7ec4\u4e2d\u83b7\u53d6\u7b2c\u516b\u4e2a\u5143\u7d20\uff0c\u800cSList<\/code>\u5b9e\u9645\u4e0a\u5fc5\u987b\u904d\u5386\u6574\u4e2a\u5217\u8868\u624d\u80fd\u5230\u8fbe\u7d22\u5f15i<\/code>\uff0c\u6240\u4ee5\u6211\u4eec\u5c06\u4ee5\u4e00\u79cd\u975e\u5e38\u4f4e\u6548\u7684\u65b9\u5f0f\u50cf\u5e38\u6570\u4e00\u6837\u626b\u63cf\u6574\u4e2a\u5217\u8868\uff0c\u5982\u679c\u6211\u4eec\u67e5\u770bSList<\/code>\uff0c\u6bd4\u5982\u67e5\u770bget<\/code>\u65b9\u6cd5\uff0c\u6211\u4eec\u53ef\u4ee5\u770b\u5230\u5b9e\u9645\u4e0a\u6d89\u53ca\u5230\u5faa\u73af\u904d\u5386\u6570\u7ec4\uff0c\u5982\u679c\u6211\u4eec\u5fc5\u987b\u4e00\u904d\u53c8\u4e00\u904d\u5730\u5faa\u73af\u904d\u5386\u6570\u7ec4\uff0c\u8fd9\u5c06\u4f1a\u975e\u5e38\u6162\uff0c\u6240\u4ee5\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\uff0c\u8fd9\u5b9e\u9645\u4e0a\u662f\u4e00\u4e2a\u53cc\u91cd\u5d4c\u5957\u7684for<\/code>\u5faa\u73af\u3002\u90a3\u4e48\u6211\u4eec\u5982\u4f55\u5904\u7406\u8fd9\u4e2a\u95ee\u9898\u5462\uff1f\u6211\u4eec\u5c06\u5728\u4e0b\u4e00\u4e2a\u89c6\u9891\u4e2d\u8ba8\u8bba\u8fd9\u4e2a\u95ee\u9898\u3002<\/p>\n\n\n\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246264-\u5c4f\u5e55\u622a\u56fe-2024-11-10-145350-1024x535.png\")
<\/figure>\n<\/div>\n\n\n8.7 Overriding Default Methods<\/h1>\n\n\n\n
\u5b58\u5728\u4e8e`List61B`\u4e2d\u7684`print`\u65b9\u6cd5\u610f\u5473\u7740\u6211\u4eec\u4e0d\u9700\u8981\u4e3a`SList`\u5355\u72ec\u7f16\u5199\u8fd9\u4e2a\u65b9\u6cd5\uff0c\u4f46\u6211\u4eec\u53ef\u4ee5\u770b\u5230\u8fd9\u79cd\u65b9\u6cd5\u76f8\u5f53\u4f4e\u6548\u3002\u90a3\u4e48\u6211\u4eec\u80fd\u505a\u4e9b\u4ec0\u4e48\u5462\uff1f\u4e00\u79cd\u65b9\u6cd5\u662f\u8986\u76d6\u201c\u8001\u677f\u201d\u7684\u51b3\u5b9a\u3002\u5f53\u7136\uff0c\u4f5c\u4e3a\u5b50\u7c7b\uff0c\u6211\u4eec\u5df2\u7ecf\u8ba8\u8bba\u8fc7\u8986\u5199\u662f\u53ef\u80fd\u7684\uff0c\u4e8b\u5b9e\u8bc1\u660e\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5b9e\u9645\u4e0a\u53ef\u4ee5\u5728`SList`\u4e2d\u7f16\u5199\u4e00\u4e2a`print`\u65b9\u6cd5\uff0c\u5373\u4f7f\u5b83\u5df2\u7ecf\u5728`List61B`\u4e2d\u5b9e\u73b0\u4e86\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u771f\u7684\u5728\u8986\u76d6\u201c\u8001\u677f\u201d\u7684\u8bbe\u5b9a\uff0c\u5ffd\u7565\u201c\u8001\u677f\u201d\u7684\u505a\u6cd5\uff0c\u6309\u7167\u6211\u4eec\u81ea\u5df1\u7684\u65b9\u5f0f\u6765\u505a\uff0c\u56e0\u4e3a\u6211\u4eec\u4fe1\u4efb\u81ea\u5df1\u3002\u6240\u4ee5\u6211\u8981\u5728\u8fd9\u91cc\u52a0\u4e0a`@Override`\u6ce8\u89e3\uff0c\u7136\u540e\u8bf4`public void print`\uff0c\u73b0\u5728\u6211\u8981\u60f3\u4e00\u60f3\u5982\u4f55\u4ee5\u66f4\u9ad8\u6548\u7684\u65b9\u5f0f\u6253\u5370\uff0c\u800c\u4e0d\u662f\u4e00\u904d\u53c8\u4e00\u904d\u5730\u83b7\u53d6\u9879\u76ee\u3002\u5b9e\u9645\u4e0a\uff0c\u66f4\u6709\u610f\u4e49\u7684\u505a\u6cd5\u662f\u9010\u4e2a\u904d\u5386\u5217\u8868\u9879\u5e76\u6253\u5370\u3002\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\u505a\uff0c\u6bd4\u5982\u8bf4`for (Node p = sentinel.next; p != null; p = p.next)`\uff0c\u8fd9\u91cc\u7684\u601d\u8def\u662f\u6211\u4f1a\u4e00\u76f4\u904d\u5386\u5230\u6307\u9488\u78b0\u5230`null`\uff0c\u6bcf\u6b21\u5faa\u73af\u7ed3\u675f\u65f6\u5411\u524d\u79fb\u52a8\u4e00\u4e2a\u8282\u70b9\uff0c\u7136\u540e\u6211\u4f1a\u5199`System.out.print(p.item + \" \")`\uff0c\u8fd9\u91cc\u6709\u4e00\u4e2a\u5c0f\u5c0f\u7684\u9519\u8bef\uff0c\u6211\u4eec\u5b9e\u9645\u4e0a\u4e0d\u60f3\u6253\u5370\u54e8\u5175\u8282\u70b9\u7684\u9879\uff0c\u800c\u662f\u4ece`sentinel.next`\u5f00\u59cb\uff0c\u4f46\u8fd9\u6bb5\u4ee3\u7801\u5e94\u8be5\u53ef\u4ee5\u5de5\u4f5c\u3002\u6240\u4ee5\u5982\u679c\u6211\u8fdb\u5165\u6f14\u793a\uff0c\u6211\u5c06\u901a\u8fc7\u8bf4\u201c\u8001\u677f\u4e0d\u77e5\u9053\u4ed6\u5728\u505a\u4ec0\u4e48\u201d\u6765\u8bc1\u660e\u5b83\u5728\u5de5\u4f5c\uff0c\u8fd9\u6837\u6211\u4eec\u5c31\u80fd\u77e5\u9053\u8fd9\u5b9e\u9645\u4e0a\u662f\u5728\u8fd0\u884c\u3002\u7136\u540e\u5f53\u6211\u8fdb\u5165\u6f14\u793a\u5e76\u518d\u6b21\u8fd0\u884c\u8fd9\u6bb5\u4ee3\u7801\u65f6\uff0c\u8001\u677f\u4e0d\u77e5\u9053\u4ed6\u5728\u505a\u4ec0\u4e48\uff0c\u9e7f\u9677\u5165\u5b58\u5728\u5371\u673a\u3002\u6240\u4ee5\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5b9e\u9645\u4e0a\u4f7f\u7528\u4e86\u8fd9\u4e2a`print`\u65b9\u6cd5\uff0c\u6211\u4eec\u77e5\u9053\u5b83\u66f4\u9ad8\u6548\uff0c\u56e0\u4e3a\u5b83\u53ea\u4f1a\u4f7f\u7528\u6bcf\u4e2a\u8282\u70b9\u4e00\u6b21\uff0c\u800c\u4e0d\u662f\u53cd\u590d\u8fed\u4ee3\u3002<\/p>\n\n\n\n
\u5c55\u793aSLList.java\u7684\u4fee\u6539\u7684\u672b\u5c3e\u90e8\u5206<\/p>\n\n\n\n
.........\n.........\n\npublic void insert(Blorp item, int position){\n if (sentinel.next = null | position = 0){\n addFirst(item);\n return;\n }\n\n Node currentNode = sentinel.next.next;\n while (position > 1 && currentNode. next \uff01= null){\n position -= 1\uff1b\n currentNode = currentNode. next;\n }\n\n Node newNode = new Node(item, currentNode.next);\n currentNode. next = newNode;\n\n}\n\/** TODO: Add a print method that overrides List61B's inefficient print method. *\/\n\/\/@Override\npublic void print() {\n System.out.println(\"The boss doesn't know what he's doing!\");\n for (Node p = sentinel.next; p \uff01= null; p = p.next){\n System.out.print(p.item +\"\")\uff1b\n }\n}<\/code><\/pre>\n\n\n\n\u5173\u4e8e\u8986\u5199\u7684\u4e00\u4e2a\u95ee\u9898\u662f\uff0c\u5b83\u975e\u5e38\u65b9\u4fbf\u3002\u8ba9\u6211\u4eec\u60f3\u8c61\u4e00\u4e0b\uff0c\u5982\u679c\u6ca1\u6709\u52a0\u4e0a`@Override`\u6ce8\u89e3\uff0c\u800c\u662f\u8bef\u6253\u4e86`prnt`\uff0c\u8fd9\u6bb5\u4ee3\u7801\u4ecd\u7136\u4f1a\u7f16\u8bd1\uff0c\u56e0\u4e3a\u62e5\u6709\u4e00\u4e2a`print`\u65b9\u6cd5\u662f\u6ca1\u95ee\u9898\u7684\uff0c\u6ca1\u6709\u4eba\u4f1a\u8bf4\u4e0d\u884c\u3002\u4f46\u73b0\u5728\u5f53\u6211\u4eec\u8c03\u7528\u6f14\u793a\u5e76\u8fd0\u884c\u4ee3\u7801\u65f6\uff0c\u5b9e\u9645\u4e0a\u4f1a\u4f7f\u7528`List61B`\u4e2d\u7684`print`\u65b9\u6cd5\u3002\u8fd9\u91cc\u7684\u9519\u8bef\u662f\u6211\u4eec\u6ca1\u6709\u52a0`i`\uff0c\u5982\u679c\u6211\u4eec\u52a0\u4e0a\u4e86`@Override`\u6807\u7b7e\uff0c\u6211\u4eec\u4f1a\u5f97\u5230\u4e00\u4e2a\u63d0\u793a\uff0c\u8bf4\u201c\u5443\uff0c\u8fd9\u4e0d\u662f\u4e00\u4e2a\u8986\u5199\u201d\uff0c\u6211\u4eec\u4f1a\u610f\u8bc6\u5230\u201c\u54e6\uff0c\u6211\u660e\u767d\u4e86\uff0c\u62fc\u9519\u4e86\u5355\u8bcd\u201d\u3002\u6240\u4ee5\u8fd9\u662f\u4e00\u4e2a\u5f88\u597d\u7684\u529f\u80fd\u3002\u8fd9\u662f\u6211\u4eec\u65b0\u7684\u66f4\u597d\u7684`print`\u65b9\u6cd5\uff0c\u5982\u679c\u4f60\u5e0c\u671b\u4e8b\u60c5\u6309\u4f60\u7684\u610f\u56fe\u5de5\u4f5c\uff0c\u4f60\u603b\u662f\u53ef\u4ee5\u8986\u5199\u5b83\u3002\u8fd9\u91cc\u6709\u4e00\u4e2a\u6211\u60f3\u8ba9\u4f60\u7b80\u77ed\u601d\u8003\u7684\u95ee\u9898\uff0c\u56de\u5fc6\u4e00\u4e0b\uff0c\u5982\u679cX\u662fY\u7684\u8d85\u7c7b\uff0c\u90a3\u4e48\u4e00\u4e2aX\u53d8\u91cf\u53ef\u4ee5\u4fdd\u5b58\u4e00\u4e2aY\u7684\u5f15\u7528\u3002\u6362\u53e5\u8bdd\u8bf4\uff0c\u4ee5\u82f1\u8bed\u4e3a\u4f8b\uff0c\u5982\u679c\u4f60\u6709\u4e00\u4e2a`List61B`\u53d8\u91cf\uff0c\u5b83\u53ef\u4ee5\u4fdd\u5b58\u4e00\u4e2a`SList`\u7684\u5730\u5740\u3002\u5728\u6211\u4eec\u4e00\u76f4\u5728\u8fd0\u884c\u7684\u793a\u4f8b\u4e2d\uff0c\u6211\u4eec\u8bbe\u7f6e`SList`\u7b49\u4e8e`new SList()`\uff0c \u200b<\/p>\n\n\n
\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246305-\u5c4f\u5e55\u622a\u56fe-2024-11-10-154618-1024x593.png\")
<\/figure>\n<\/div>\n\n\n\u73b0\u5728\u7684\u95ee\u9898\u662f\uff0c\u5982\u679c\u6211\u4eec\u628a\u8fd9\u4e2a\u6539\u4e3a`List61B`\uff0c\u8fd9\u4f1a\u5de5\u4f5c\u5417\uff1f\u6211\u4eec\u77e5\u9053\u5b83\u4f1a\u7f16\u8bd1\uff0c\u56e0\u4e3a\u4e4b\u524d\u5df2\u7ecf\u77e5\u9053\u4e86\uff0c\u4f46\u95ee\u9898\u662f\uff0c\u4f60\u8ba4\u4e3a\u5b83\u4f1a\u8c03\u7528\u54ea\u4e2a`print`\u65b9\u6cd5\uff1f\u6240\u4ee5\u8bf7\u601d\u8003\u4e00\u4e0b\u4f60\u7684\u60f3\u6cd5\u3002\u4e8b\u5b9e\u8bc1\u660e\uff0c\u5b83\u5b9e\u9645\u4e0a\u4f1a\u4f7f\u7528\u4f60\u5e0c\u671b\u7684\u90a3\u4e2a\uff0c\u5373`SList`\u4e2d\u7684`print`\u65b9\u6cd5\u3002\u4e8b\u5b9e\u4e0a\uff0c\u8ba9\u6211\u4eec\u8bd5\u4e00\u8bd5\uff0c\u6211\u4eec\u8fd0\u884c\u5b83\uff0c\u6211\u4eec\u5f97\u5230\u201c\u8001\u677f\u4e0d\u77e5\u9053\u4ed6\u5728\u505a\u4ec0\u4e48\uff0c\u9e7f\u9677\u5165\u5b58\u5728\u5371\u673a\u201d\uff0c\u8fd9\u5f88\u597d\uff0c\u8fd9\u662f\u5408\u4e4e\u903b\u8f91\u7684\u9009\u62e9\uff0c\u95ee\u9898\u662f\u5b83\u662f\u5982\u4f55\u5de5\u4f5c\u7684\u3002\u6240\u4ee5\u8fd9\u662f\u4e00\u4e2a\u7a0d\u5fae\u590d\u6742\u7684\u8bdd\u9898\uff0c\u6211\u4f1a\u5728\u4e0b\u4e00\u4e2a\u89c6\u9891\u4e2d\u7ee7\u7eed\u8bb2\u89e3\uff0c\u4f46\u5b83\u5b9e\u9645\u4e0a\u6bd4\u4f60\u60f3\u8c61\u7684\u8981\u7b80\u5355\u5f97\u591a\u3002\u901a\u5e38\u4eba\u4eec\u5728\u7b2c\u4e00\u6b21\u63a5\u89e6Java\u65f6\u4f1a\u611f\u5230\u56f0\u60d1\uff0c\u4e0d\u77e5\u9053\u4ec0\u4e48\u65f6\u5019\u4f1a\u8c03\u7528\u54ea\u4e2a\u65b9\u6cd5\uff0c\u4f46\u6211\u4eec\u4f1a\u8be6\u7ec6\u89e3\u91ca\u8fd9\u4e00\u70b9\u3002<\/p>\n\n\n\n
8.8Dynamic Method Solution <\/h1>\n\n\n\n
\u7406\u89e3\u8fd9\u4e00\u70b9\u662f\u5982\u4f55\u5de5\u4f5c\u7684\u975e\u5e38\u91cd\u8981\uff0c\u4e0d\u5e78\u7684\u662f\uff0c\u8fd9\u662f\u4e00\u4ef6\u5f88\u5bb9\u6613\u5b66\u4f1a\u4e00\u5957\u8fc7\u4e8e\u590d\u6742\u7684\u62dc\u5360\u5ead\u5f0f\u89c4\u5219\u7684\u4e8b\u60c5\uff0c\u4f46\u5b9e\u9645\u4e0a\u6709\u4e00\u79cd\u7b80\u5355\u7684\u65b9\u5f0f\u6765\u601d\u8003\u5b83\u3002\u6240\u4ee5\uff0c\u601d\u8003\u8fd9\u4e2a\u95ee\u9898\u7684\u65b9\u5f0f\u662f\uff0cJava\u4e2d\u7684\u6bcf\u4e00\u4e2a\u53d8\u91cf\u5728\u58f0\u660e\u65f6\u90fd\u6709\u4e00\u4e2a\u7f16\u8bd1\u65f6\u7c7b\u578b\uff0c\u6211\u6709\u65f6\u4e5f\u79f0\u5176\u4e3a\u9759\u6001\u7c7b\u578b\uff0c\u8fd9\u4e2a\u7c7b\u578b\u6c38\u8fdc\u4e0d\u4f1a\u6539\u53d8\u3002\u4f8b\u5982\uff0c\u5f53\u6211\u58f0\u660e`LivingThing lt1`\u65f6\uff0c\u6211\u5f97\u5230\u4e86\u4e00\u4e2a\u5185\u5b58\u76d2\uff0c\u8fd9\u4e2a\u5185\u5b58\u76d2\u662f64\u4f4d\u7684\uff0c\u5b83\u53ea\u80fd\u6307\u5411\u4e00\u4e2a`LivingThing`\u3002<\/p>\n\n\n
\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246325-\u5c4f\u5e55\u622a\u56fe-2024-11-10-154911-1024x578.png\")
<\/figure>\n<\/div>\n\n\n\u6bcf\u4e2a\u53d8\u91cf\u8fd8\u6709\u4e00\u4e2a\u52a8\u6001\u7c7b\u578b\uff0c\u6709\u65f6\u79f0\u4e3a\u8fd0\u884c\u65f6\u7c7b\u578b\uff0c\u8fd9\u662f\u5728\u5b9e\u4f8b\u5316\u65f6\u6307\u5b9a\u7684\u7c7b\u578b\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u5f53\u4f60\u4f7f\u7528`new`\u5173\u952e\u5b57\u65f6\uff0c\u5b83\u7b49\u4e8e\u88ab\u6307\u5411\u7684\u5bf9\u8c61\u7684\u7c7b\u578b\uff0c\u8fd9\u5c31\u662f\u6211\u4eec\u6240\u8bf4\u7684\u8fd0\u884c\u65f6\u7c7b\u578b\u3002\u6240\u4ee5\u5728\u8fd9\u4e00\u70b9\u4e0a\uff0c\u6211\u8fd8\u6ca1\u6709\u5b9e\u4f8b\u5316\u4efb\u4f55\u4e1c\u897f\uff0c\u6240\u4ee5\u52a8\u6001\u7c7b\u578b\u5c06\u53ea\u662f\u6807\u6ce8\u4e3a`null`\u3002<\/p>\n\n\n\n
\u63a5\u4e0b\u6765\u662f\u8fd9\u4e00\u884c\u4ee3\u7801\uff0c\u6211\u4eec\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u72d0\u72f8\u5bf9\u8c61\uff0c\u5e76\u8bf4`lt1`\u7b49\u4e8e\u8fd9\u4e2a\u65b0\u72d0\u72f8\u5bf9\u8c61\uff0c\u6240\u4ee5\u4e00\u4e2a\u65b0\u7684\u72d0\u72f8\u5bf9\u8c61\u88ab\u521b\u5efa\u4e86\uff0c\u6211\u4eec\u590d\u5236\u4e86\u5b83\u7684\u5730\u5740\uff0c`lt1`\u6307\u5411\u4e86\u8fd9\u4e2a\u751f\u7269\uff0c\u73b0\u5728\u6211\u4eec\u6709\u4e86\u4e00\u4e2a\u52a8\u6001\u7c7b\u578b\uff0c\u5b83\u662f\u72d0\u72f8\uff0c\u5373\u88ab\u6307\u5411\u7684\u5bf9\u8c61\u7684\u7c7b\u578b\u3002<\/p>\n\n\n\n
\u6211\u4eec\u7ee7\u7eed\uff0c\u4e0b\u4e00\u884c\u4ee3\u7801\u662f`Animal a1 = lt1`\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u5f97\u5230\u4e86\u4e00\u4e2a\u65b0\u7684\u5185\u5b58\u76d2\uff0c\u5b83\u4fdd\u5b58\u52a8\u7269\u7684\u5f15\u7528\uff0c\u5b83\u7684\u9759\u6001\u7c7b\u578b\u662f\u52a8\u7269\uff0c\u800c\u4e14\u6c38\u8fdc\u4e0d\u4f1a\u6539\u53d8\uff0c\u4e8b\u5b9e\u4e0a\uff0c\u4f60\u53ef\u4ee5\u770b\u5230\u5b83\u5c31\u50cf\u523b\u5728\u76d2\u5b50\u4e0a\u4e00\u6837\uff0c\u65e0\u6cd5\u53bb\u9664\uff0c\u5b83\u7684\u52a8\u6001\u7c7b\u578b\u662f\u72d0\u72f8\u3002\u6211\u4eec\u4e5f\u53ef\u4ee5\u6709\u9759\u6001\u7c7b\u578b\u4e3a\u72d0\u72f8\u7684\u53d8\u91cf\uff0c\u8fd9\u662f\u5b8c\u5168\u53ef\u4ee5\u7684\u3002\u6240\u4ee5\u6211\u521b\u5efa\u4e00\u4e2a\u9759\u6001\u7c7b\u578b\u4e3a\u72d0\u72f8\u7684\u53d8\u91cf\uff0c\u5b83\u4e5f\u6307\u5411\u4e00\u53ea\u72d0\u72f8\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u9759\u6001\u7c7b\u578b\u548c\u52a8\u6001\u7c7b\u578b\u90fd\u662f\u72d0\u72f8\u3002<\/p>\n\n\n
\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246344-\u5c4f\u5e55\u622a\u56fe-2024-11-10-155027-1024x556.png\")
<\/figure>\n<\/div>\n\n\n\u6700\u540e\uff0c\u6211\u4eec\u51b3\u5b9a
lt1<\/code>\u73b0\u5728\u5c06\u6307\u5411\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\uff0c\u8fd9\u662f\u4e00\u4e2a\u4e4c\u8d3c\u5bf9\u8c61\uff0c\u6240\u4ee5\u9759\u6001\u7c7b\u578b\u5f53\u7136\u4e0d\u4f1a\u6539\u53d8\uff0c\u56e0\u4e3a\u5b83\u6c38\u8fdc\u4e0d\u4f1a\u6539\u53d8\uff0c\u4f46\u52a8\u6001\u7c7b\u578b\u73b0\u5728\u53d8\u6210\u4e86\u4e4c\u8d3c\u3002\u597d\u7684\uff0c\u5f88\u68d2\u3002
![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246371-\u5c4f\u5e55\u622a\u56fe-2024-11-10-155107.png\")
<\/p>\n\n\n\n\u90a3\u4e48\uff0c\u8fd9\u662f\u89c4\u5219\u90e8\u5206\u3002\u5982\u679c\u4f60\u77e5\u9053\u67d0\u4e2a\u5bf9\u8c61\u7684\u52a8\u6001\u7c7b\u578b\uff0c\u90a3\u4e48\u4f60\u5c31\u77e5\u9053\u5728\u8c03\u7528\u8986\u5199\u65b9\u6cd5\u65f6\u4f1a\u53d1\u751f\u4ec0\u4e48\u3002\u5047\u8bbe\u6211\u4eec\u4f7f\u7528\u4e00\u4e2a\u7f16\u8bd1\u65f6\u7c7b\u578b\u4e3aX\u3001\u8fd0\u884c\u65f6\u7c7b\u578b\u4e3aY\u7684\u53d8\u91cf\u6765\u8c03\u7528\u4e00\u4e2a\u5bf9\u8c61\u7684\u65b9\u6cd5\uff0c\u4f8b\u5982\uff0c\u7f16\u8bd1\u65f6\u7c7b\u578b\u4e3a`List`\uff0c\u8fd0\u884c\u65f6\u7c7b\u578b\u4e3a`SList`\uff0c\u5982\u8fd9\u91cc\u6240\u793a\uff0c\u90a3\u4e48\u5982\u679c\u52a8\u6001\u7c7b\u578b\u8986\u5199\u4e86\u8be5\u65b9\u6cd5\uff0c\u5219\u5c06\u4f7f\u7528\u52a8\u6001\u7c7b\u578b\u7684\u8be5\u65b9\u6cd5\uff0c\u8fd9\u5c31\u662f\u6240\u8c13\u7684\u52a8\u6001\u65b9\u6cd5\u9009\u62e9\u3002\u8fd9\u4e2a\u672f\u8bed\u6709\u70b9\u6666\u6da9\uff0c\u4e5f\u4e0d\u662f\u5b8c\u5168\u6807\u51c6\u7684\uff0c\u4f46\u6211\u4eec\u5728\u8bfe\u7a0b\u4e2d\u4f7f\u7528\u5b83\u3002\u6240\u4ee5\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u65e0\u8bba\u4f55\u65f6\u6211\u4eec\u8c03\u7528\u67d0\u4e2a\u65b9\u6cd5\uff0c\u5373\u4f7f\u6211\u4eec\u4f7f\u7528\u7684\u662f\u7f16\u8bd1\u65f6\u7c7b\u578b\u4e3a`List`\u7684\u53d8\u91cf`s1`\uff0c\u7531\u4e8e`SList`\u7c7b\u8986\u5199\u4e86\u8be5\u65b9\u6cd5\uff0c\u6211\u4eec\u5c06\u4f7f\u7528\u52a8\u6001\u7c7b\u578b\u7684\u8be5\u65b9\u6cd5\u3002\u8fd9\u5c31\u662f\u4f60\u770b\u5230\u7684\u73b0\u8c61\uff0c\u5373\u4f7f\u53d8\u91cf\u7684\u7f16\u8bd1\u65f6\u7c7b\u578b\u662f`List`\uff0c\u5b9e\u9645\u8c03\u7528\u7684\u5374\u662f`SList`\u4e2d\u7684\u65b9\u6cd5\u3002<\/p>\n\n\n\n
8.9 Dynamic Method solution and overloaded Solution<\/h1>\n\n\n
\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246407-\u5c4f\u5e55\u622a\u56fe-2024-11-10-161658-1024x586.png\")
<\/figure>\n<\/div>\n\n\n\u6b63\u5982\u6211\u5728\u4e0a\u4e00\u4e2a\u89c6\u9891\u4e2d\u63d0\u5230\u7684\uff0c\u786e\u5b9a\u5728\u52a8\u6001\u65b9\u6cd5\u9009\u62e9\u60c5\u51b5\u4e0b\u8c03\u7528\u4ec0\u4e48\u65b9\u6cd5\u7684\u89c4\u5219\u5b9e\u9645\u4e0a\u975e\u5e38\u7b80\u5355\u3002\u7136\u800c\uff0c\u6211\u4eec\u7684\u76f4\u89c9\u6709\u65f6\u4f1a\u8bef\u5bfc\u6211\u4eec\uff0c\u6211\u4eec\u4f1a\u5bfb\u627e\u6a21\u5f0f\u6216\u5047\u8bbeJava\u8bed\u8a00\u4f1a\u505a\u4e00\u4e9b\u770b\u8d77\u6765\u6bd4\u7b80\u5355\u89c4\u5219\u66f4\u5408\u7406\u7684\u4e8b\u60c5\u3002\u597d\uff0c\u6211\u8fd9\u91cc\u6709\u4e00\u4e2a\u4f8b\u5b50\uff0c\u5b83\u5c55\u793a\u4e86\u6211\u521a\u5f00\u59cb\u5b66\u4e60Java\u65f6\u72af\u7684\u4e00\u4e2a\u9519\u8bef\uff0c\u4f60\u4eec\u4e5f\u5f88\u6709\u53ef\u80fd\u72af\u540c\u6837\u7684\u9519\u8bef\u3002\u6240\u4ee5\uff0c\u4f60\u4eec\u7684\u4efb\u52a1\u662f\u5f04\u6e05\u695a\u8fd9\u6bb5\u4ee3\u7801\u8fd0\u884c\u7684\u7ed3\u679c\u662f\u4ec0\u4e48\u3002\u8ba9\u6211\u6765\u4ecb\u7ecd\u4e00\u4e0b\u8fd9\u4e2a\u95ee\u9898\u7684\u80cc\u666f\uff0c\u6211\u4eec\u6709\u4e00\u4e2a\u540d\u4e3a`Animal`\u7684\u63a5\u53e3\uff0c\u5b83\u63d0\u4f9b\u4e86`greet`\u3001`sniff`\u548c`flatter`\u65b9\u6cd5\uff0c\u6240\u6709\u8fd9\u4e9b\u90fd\u662f\u9ed8\u8ba4\u65b9\u6cd5\u3002\u6211\u5728\u8fd9\u91cc\u6709\u70b9\u4f5c\u5f0a\uff0c\u53bb\u6389\u4e86`System.out`\uff0c\u56e0\u4e3a\u6211\u60f3\u8ba9\u6240\u6709\u5185\u5bb9\u90fd\u80fd\u653e\u5728\u4e00\u5f20\u5e7b\u706f\u7247\u4e0a\uff0c\u4f46\u6211\u8ba4\u4e3a\u6982\u5ff5\u4ecd\u7136\u662f\u6e05\u6670\u7684\u3002\u7136\u540e\uff0c\u6211\u8fd9\u91cc\u6709\u4e00\u4e2a\u540d\u4e3a`Dog`\u7684\u7c7b\uff0c\u5b83\u5b9e\u73b0\u4e86`Animal`\u63a5\u53e3\uff0c\u5e76\u63d0\u4f9b\u4e86`sniff`\u548c`flatterDog`\u65b9\u6cd5\u3002\u4f60\u4eec\u7684\u4efb\u52a1\u662f\u5f04\u6e05\u695a\u5f53\u6211\u8fd0\u884c\u8fd9\u6bb5\u4ee3\u7801\u65f6\u4f1a\u53d1\u751f\u4ec0\u4e48\u3002<\/p>\n\n\n\n
\u6211\u6709\u4e24\u4e2a\u53d8\u91cf\uff0c\u4e00\u4e2a\u662f`Animal a`\uff0c\u53e6\u4e00\u4e2a\u662f`Dog d`\uff0c\u6240\u4ee5\u5b83\u4eec\u7684\u9759\u6001\u7c7b\u578b\u5206\u522b\u662f`Animal`\u548c`Dog`\u3002\u73b0\u5728\u5b83\u4eec\u90fd\u88ab\u8bbe\u7f6e\u4e3a\u4e00\u4e2a\u65b0\u7684`Dog`\u5bf9\u8c61\uff0c\u56e0\u6b64`a`\u548c`d`\u6240\u6307\u5411\u7684\u5bf9\u8c61\u7684\u52a8\u6001\u7c7b\u578b\u90fd\u662f`Dog`\u3002\u7136\u540e\u6211\u4eec\u6709\u4e00\u7cfb\u5217\u7684\u65b9\u6cd5\u8c03\u7528\uff0c\u5176\u4e2d\u4e09\u4e2a\u4f7f\u7528\u4e86\u9759\u6001\u7c7b\u578b\u4e3a`Animal`\u7684\u53d8\u91cf`a`\uff0c\u4e00\u4e2a\u4f7f\u7528\u4e86\u9759\u6001\u7c7b\u578b\u4e3a`Dog`\u7684\u53d8\u91cf`d`\u3002\u73b0\u5728\uff0c\u8bf7\u601d\u8003\u4e00\u4e0b\u4f60\u8ba4\u4e3a\u6bcf\u884c\u4ee3\u7801\u4f1a\u505a\u4ec0\u4e48\uff0c\u8fd9\u662f\u4e00\u4e2a\u975e\u5e38\u91cd\u8981\u7684\u8c1c\u9898\uff0c\u6240\u4ee5\u5982\u679c\u4f60\u5728\u5bb6\u91cc\u89c2\u770b\uff0c\u8bf7\u52a1\u5fc5\u5c1d\u8bd5\u5f97\u51fa\u7b54\u6848\u5e76\u8ba4\u771f\u601d\u8003\uff0c\u7136\u540e\u5c06\u4f60\u7684\u7b54\u6848\u4e0e\u6211\u7684\u8fdb\u884c\u6bd4\u8f83\uff0c\u5e0c\u671b\u4f60\u4f1a\u72af\u6211\u5e0c\u671b\u4f60\u72af\u7684\u9519\u8bef\uff0c\u6216\u8005\u66f4\u597d\uff0c\u6839\u672c\u4e0d\u72af\u9519\u8bef\uff0c\u6211\u4eec\u6765\u770b\u770b\u3002<\/p>\n\n\n
\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246416-\u5c4f\u5e55\u622a\u56fe-2024-11-10-161847-1024x517.png\")
<\/figure>\n<\/div>\n\n\n\u9996\u5148\uff0c\u6211\u4eec\u6765\u770b`a.greet(d)`\uff0c\u8fd9\u91cc\u6211\u4eec\u6709\u4e00\u4e2a\u7c7b\u578b\u4e3a`Animal`\u7684\u53d8\u91cf\uff0c\u6240\u4ee5\u6211\u4eec\u67e5\u627e\u662f\u5426\u6709\u53ef\u4ee5\u63a5\u53d7\u7c7b\u578b\u4e3a`Dog`\u7684\u53c2\u6570\u7684`greet`\u65b9\u6cd5\uff0c\u7b54\u6848\u5b9e\u9645\u4e0a\u662f\u6709\u7684\uff0c\u56e0\u4e3a`Dog`\u662f`Animal`\u7684\u4e00\u79cd\uff0c\u6240\u4ee5\u5b83\u53ef\u4ee5\u653e\u5165\u8fd9\u4e2a`Animal`\u7c7b\u578b\u7684\u53c2\u6570\u4e2d\uff0c\u6ca1\u95ee\u9898\u3002\u6240\u4ee5\u5f53\u8fd9\u884c\u4ee3\u7801\u8fd0\u884c\u65f6\uff0c\u6211\u4eec\u5f97\u5230\u7684\u662f\u201cHello Animal\u201d\u3002<\/p>\n\n\n\n
\u63a5\u4e0b\u6765\u662f`a.sniff(d)`\uff0c\u90a3\u4e48\u8fd9\u91cc\u4f1a\u53d1\u751f\u4ec0\u4e48\u5462\uff1fJava\u4f1a\u8bf4\u6709\u6ca1\u6709\u53ef\u4ee5\u5904\u7406`Dog`\u7684\u65b9\u6cd5\uff0c\u6709\u7684\uff0c\u5c31\u662f`sniff(Animal a)`\u3002\u56e0\u4e3a`Dog`\u662f`Animal`\u7684\u4e00\u79cd\uff0c\u6240\u4ee5\u4f60\u53ef\u4ee5\u8c03\u7528\u8fd9\u4e2a\u65b9\u6cd5\u3002\u4f46\u7531\u4e8e\u52a8\u6001\u65b9\u6cd5\u9009\u62e9\u7684\u9b54\u6cd5\uff0c`Dog`\u4e5f\u63d0\u4f9b\u4e86\u4e00\u4e2a`sniff(Animal a)`\u65b9\u6cd5\uff0c\u8fd9\u662f\u5bf9\u539f\u59cb`sniff`\u65b9\u6cd5\u7684\u8986\u5199\uff0c\u6240\u4ee5\u6211\u4eec\u4f1a\u5f97\u5230`Dog`\u7684`sniff`\u65b9\u6cd5\uff0c\u5373\u4f7f\u8fd9\u91cc\u6ca1\u6709`@Override`\u6ce8\u89e3\uff0c\u8fd9\u4e5f\u662f\u53ef\u9009\u7684\uff0c\u4f46\u572861B\u8bfe\u7a0b\u4e2d\u4f60\u5e94\u8be5\u603b\u662f\u52a0\u4e0a`@Override`\u6ce8\u89e3\u3002<\/p>\n\n\n\n
\u73b0\u5728\uff0c\u6211\u4eec\u8bd5\u7740\u8ba9\u4e00\u6761\u72d7\u606d\u7ef4\u53e6\u4e00\u6761\u72d7\uff0c`d.flatterDog(d)`\u4f1a\u53d1\u751f\u4ec0\u4e48\uff1fJava\u4f1a\u8bf4\u563f\uff0c`Dog`\uff0c\u4f60\u6709\u6ca1\u6709\u53ef\u4ee5\u606d\u7ef4\u72d7\u7684\u65b9\u6cd5\uff1f\u6709\u7684\uff0c\u597d\u7684\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c`d.flatterDog(d)`\u4f1a\u8c03\u7528\u8fd9\u4e2a\u65b9\u6cd5\uff0c\u6211\u4eec\u4f1a\u5f97\u5230\u201c\u4f60\u771f\u9177\uff0c\u72d7\u201d\u3002<\/p>\n\n\n\n
\u6700\u540e\uff0c\u6211\u4eec\u6765\u770b`a.flatter(d)`\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0cJava\u4f1a\u8bf4`Animal`\uff0c\u4f60\u6709\u6ca1\u6709\u4e00\u4e2a\u53ef\u4ee5\u5904\u7406\u72d7\u7684`flatter`\u65b9\u6cd5\uff1f\u6709\u7684\uff0c\u597d\u7684\uff0c\u8fd9\u91cc\u6709\u3002\u6709\u4e9b\u4eba\u53ef\u80fd\u4f1a\u60f3\uff0c\u597d\u5427\uff0c`Dog`\u6709\u4e00\u4e2a\u66f4\u597d\u7684\u65b9\u6cd5\uff0c\u6240\u4ee5\u5e94\u8be5\u662f\u201c\u4f60\u771f\u9177\uff0c\u72d7\u201d\uff0c\u56e0\u4e3a\u8fd9\u4e2a\u65b9\u6cd5\u66f4\u5177\u4f53\u3002\u4f46\u5b9e\u9645\u4e0a\u6b63\u786e\u7b54\u6848\u662f\u201c\u4f60\u771f\u9177\uff0c\u52a8\u7269\u201d\u3002\u6240\u4ee5\uff0c\u5bf9\u4e8e\u90a3\u4e9b\u72af\u4e86\u8fd9\u4e2a\u7279\u5b9a\u9519\u8bef\u7684\u4eba\uff0c\u5373\u4f7f\u662f\u6700\u8fd1\u6211\u548c\u6211\u7684\u52a9\u6559\u8ba8\u8bba\u7c7b\u4f3c\u7684\u95ee\u9898\u65f6\uff0c\u4ed6\u4eec\u4e5f\u4f1a\u95ee\u201c\u4ec0\u4e48\uff1f\u201d \u8fd9\u662f\u4e00\u4e2a\u975e\u5e38\u5bb9\u6613\u72af\u7684\u9519\u8bef\uff0c\u9664\u975e\u4f60\u4ed4\u7ec6\u601d\u8003\uff0c\u8fd9\u770b\u8d77\u6765\u53ef\u80fd\u6709\u4e9b\u5413\u4eba\uff0c\u4f46\u7b54\u6848\u5176\u5b9e\u5f88\u7b80\u5355\u3002<\/p>\n\n\n\n
\u7b54\u6848\u662f\uff0c\u5982\u679c\u6211\u4eec\u67e5\u770b`flatter(Animal)`\u548c`flatter(Dog)`\uff0c\u5b83\u4eec\u7684\u7b7e\u540d\u5e76\u4e0d\u76f8\u540c\u3002\u6211\u4eec\u5b9a\u4e49\u8986\u5199\u7684\u65b9\u6cd5\u662f\u5fc5\u987b\u5177\u6709\u5b8c\u5168\u76f8\u540c\u7684\u7b7e\u540d\uff0c\u800c\u8fd9\u4e9b\u7b7e\u540d\u5e76\u4e0d\u76f8\u540c\uff0c`Animal`\u548c`Dog`\u4e0d\u662f\u540c\u4e00\u4e2a\u7c7b\u578b\u3002\u6240\u4ee5\u8fd9\u662f\u4e00\u4e2a\u91cd\u8f7d\u7684\u4f8b\u5b50\uff0c\u800c\u4e0d\u662f\u8986\u5199\u3002<\/p>\n\n\n\n
\u53e6\u4e00\u79cd\u601d\u8003\u8fd9\u4e2a\u95ee\u9898\u7684\u65b9\u6cd5\u662f\u6240\u8c13\u7684\u201c\u65b9\u6cd5\u9009\u62e9\u7b97\u6cd5\u201d\u3002\u8fd9\u53ea\u662f\u6211\u601d\u8003\u7684\u4e00\u4e2a\u65b9\u6cd5\uff0c\u6211\u4e5f\u53d1\u73b0\u8fd9\u79cd\u65b9\u6cd5\u6709\u52a9\u4e8e\u5411\u5b66\u751f\u89e3\u91ca\u8fd9\u4e2a\u95ee\u9898\u3002\u8fd9\u542c\u8d77\u6765\u53ef\u80fd\u6709\u70b9\u672f\u8bed\u5316\uff0c\u4f46\u6211\u4eec\u4f1a\u628a\u5b83\u4e0e\u521a\u624d\u7684\u95ee\u9898\u8054\u7cfb\u8d77\u6765\u3002<\/p>\n\n\n\n
Consider the function call foo. bar(x1), where foo has static type TPrime, and x1 has static type T1.
At compi le time, the compiler verifies that TPrime has a method that can handle T1. It then records the signature of this method.<\/p>\n\n\n\n- \n
- Note: If there are multiple methods that can handle T1, the compiler records the \"most specific\" one. For example, if T1=Dog, and TPrime has bar(Dog) and bar(Animal), it wil record bar(Dog).<\/li>\n<\/ul>\n\n\n\n
At runtime, if foo's dynamic type overrides the recorded signature, use the overridden method. Otherwise, use TPrime's version of the method.
TO NOTE : We did not see this in our lecture puzzle, but see study guide for more! <\/strong><\/p>\n\n\n\n\u8ba9\u6211\u4eec\u8003\u8651\u4e00\u4e2a\u51fd\u6570\u8c03\u7528\uff0c\u5f62\u5f0f\u5982\u4e0b\uff1a`foo.bar(x1)`\uff0c\u5176\u4e2d`foo`\u662f\u8c03\u7528\u53d8\u91cf\u6216\u8868\u8fbe\u5f0f\uff0c`bar`\u662f\u65b9\u6cd5\u540d\uff0c\u6211\u4eec\u4f20\u5165\u4e00\u4e2a\u53d8\u91cf`x1`\u3002\u5047\u8bbe`foo`\u7684\u9759\u6001\u7c7b\u578b\u662f`T'`\uff0c`x1`\u7684\u9759\u6001\u7c7b\u578b\u662f`T1`\u3002\u90a3\u4e48\u5728\u7f16\u8bd1\u65f6\uff0c\u7f16\u8bd1\u5668\u9700\u8981\u786e\u4fdd\u4e00\u5207\u6b63\u5e38\uff0c\u7f16\u8bd1\u5668\u4f1a\u9a8c\u8bc1`T'`\u662f\u5426\u6709\u4e00\u4e2a\u53ef\u4ee5\u5904\u7406`T1`\u7684\u65b9\u6cd5\uff0c\u5c31\u50cf\u6211\u4eec\u95ee`Animal`\u662f\u5426\u6709\u53ef\u4ee5\u5904\u7406`Dog`\u7684\u65b9\u6cd5\u4e00\u6837\u3002\u627e\u5230\u5339\u914d\u7684\u65b9\u6cd5\u540e\uff0c\u7f16\u8bd1\u5668\u4f1a\u8bb0\u5f55\u8be5\u65b9\u6cd5\u7684\u7b7e\u540d\uff0c\u5e76\u5c06\u5176\u5199\u5728\u4e00\u4e2a\u5730\u65b9\uff0c\u6bd4\u5982\u8bf4\u662f\u201c\u6211\u4eec\u9700\u8981\u8c03\u7528\u7684\u65b9\u6cd5\u662f\u4e00\u4e2a`Animal`\u7c7b\u578b\u7684\u65b9\u6cd5\uff0c\u5176\u7b7e\u540d\u662f`flatter(Animal)`\u201d\uff0c\u5b83\u4f1a\u8bb0\u5f55\u4e0b\u8fd9\u4e2a\u7b7e\u540d`flatter(Animal)`\u3002<\/p>\n\n\n\n
\u4e00\u4e2a\u5c0f\u7684\u4fa7\u6ce8\uff0c\u5982\u679c\u5b9e\u9645\u4e0a\u6709\u591a\u4e2a\u65b9\u6cd5\u53ef\u4ee5\u5904\u7406`T1`\uff0c\u7f16\u8bd1\u5668\u4f1a\u9009\u62e9\u6700\u5177\u4f53\u7684\u4e00\u4e2a\u3002\u5728\u6211\u4eec\u7684\u5c0f\u4f8b\u5b50\u4e2d\u6ca1\u6709\u8fd9\u79cd\u60c5\u51b5\uff0c\u4f46\u7ec3\u4e60\u6307\u5357\u4e2d\u6709\u7c7b\u4f3c\u7684\u95ee\u9898\u3002\u4f8b\u5982\uff0c\u5982\u679c\u7c7b\u578b\u662f`Dog`\uff0c\u800c`T'`\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\u662f`Animal`\uff0c\u5e76\u4e14\u65e2\u6709`flatter(Dog)`\u4e5f\u6709`flatter(Animal)`\u65b9\u6cd5\uff0c\u5b83\u4f1a\u9009\u62e9`Dog`\u7248\u672c\uff0c\u56e0\u4e3a\u8fd9\u662f\u66f4\u5177\u4f53\u7684\u4e00\u4e2a\u3002\u4f46\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\u6211\u4eec\u6ca1\u6709\u8fd9\u6837\u7684\u65b9\u6cd5\u3002<\/p>\n\n\n\n
\u6240\u4ee5\uff0c\u5230\u4e86\u8fd0\u884c\u65f6\uff0c\u5982\u679c`foo`\u7684\u52a8\u6001\u7c7b\u578b\uff08\u4e5f\u5c31\u662f`a`\u7684\u52a8\u6001\u7c7b\u578b\uff0c\u8fd9\u91cc\u662f`Dog`\uff09\u8986\u5199\u4e86\u90a3\u4e2a\u8bb0\u5f55\u7684\u7b7e\u540d\uff08\u8fd9\u91cc\u662f`flatter(Animal)`\uff09\uff0c\u90a3\u4e48\u6211\u4eec\u4f1a\u4f7f\u7528\u8986\u5199\u7684\u65b9\u6cd5\u3002\u5728\u8fd9\u91cc\uff0c`Dog`\u5e76\u6ca1\u6709\u8986\u5199`flatter(Animal)`\uff0c\u6240\u4ee5\u7ed3\u679c\u662f\uff0c\u6211\u4eec\u6700\u7ec8\u4f7f\u7528\u7684\u662f`T'`\u7248\u672c\u7684\u65b9\u6cd5\u3002\u8fd9\u5c31\u662f\u4ece\u7b97\u6cd5\u89d2\u5ea6\u6765\u770b\u8fd9\u4e2a\u95ee\u9898\u7684\u65b9\u6cd5\u3002\u5982\u679c\u4f60\u4e0d\u559c\u6b22\u8fd9\u4e2a\u7b80\u77ed\u7684\u89e3\u91ca\uff0c\u8fd9\u91cc\u6709\u4e00\u4e2a\u66f4\u957f\u7684\u7248\u672c\uff0c\u4f46\u5b83\u4eec\u5b9e\u9645\u4e0a\u662f\u7b49\u4ef7\u7684\u3002<\/p>\n\n\n\n
\u6700\u540e\uff0c\u8ba9\u6211\u4eec\u518d\u4ece\u89c6\u89c9\u4e0a\u770b\u4e00\u6b21\uff0c\u6bcf\u5f53\u8fd9\u6bb5\u4ee3\u7801\u88ab\u7f16\u8bd1\u65f6\uff0c\u7f16\u8bd1\u5668\u4f1a\u8bf4\uff1a\u201c\u6709\u6ca1\u6709\u4e00\u4e2a`Animal`\u7c7b\u578b\u7684\u65b9\u6cd5\u53ef\u4ee5\u5904\u7406`Dog`\u5bf9\u8c61\uff1f\u201d \u6709\u7684\uff0c\u5bf9\u5427\uff1f\u90a3\u4e48\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u53eb\u4ec0\u4e48\u540d\u5b57\uff1f\u5b83\u53eb`flatter(Animal)`\uff0c\u6240\u4ee5\u5b83\u4f1a\u628a\u8fd9\u4e2a\u7b7e\u540d\u8bb0\u5f55\u4e0b\u6765\u3002\u7136\u540e\uff0c\u5f53\u4ee3\u7801\u5b9e\u9645\u8fd0\u884c\u65f6\uff0c\u5b83\u5fc5\u987b\u4f7f\u7528\u5177\u6709\u8be5\u786e\u5207\u7b7e\u540d\u7684\u65b9\u6cd5\uff0c\u56e0\u4e3a\u8fd9\u5c31\u662f\u8986\u5199\u7684\u610f\u4e49\u6240\u5728\u3002<\/p>\n\n\n\n
\u5e0c\u671b\u8fd9\u5bf9\u4f60\u6709\u6240\u5e2e\u52a9\uff0c\u4e00\u5b9a\u8981\u67e5\u770b\u7ec3\u4e60\u6307\u5357\uff0c\u5b66\u751f\u4e00\u5f00\u59cb\u4f1a\u89c9\u5f97\u8fd9\u4e2a\u95ee\u9898\u4ee4\u4eba\u6cae\u4e27\uff0c\u4f46\u4e00\u65e6\u4f60\u505a\u4e86\u6b63\u786e\u7684\u7ec3\u4e60\u5e76\u57f9\u517b\u4e86\u6b63\u786e\u7684\u76f4\u89c9\uff0c\u89c4\u5219\u5b9e\u9645\u4e0a\u662f\u975e\u5e38\u7b80\u5355\u7684\u3002\u57fa\u672c\u4e0a\uff0c\u8fd9\u5f52\u7ed3\u4e3a\uff1a\u65b9\u6cd5\u9009\u62e9\u57fa\u4e8e\u7f16\u8bd1\u65f6\u7c7b\u578b\uff0c\u4f46\u5b9e\u9645\u8c03\u7528\u7684\u65b9\u6cd5\u53d6\u51b3\u4e8e\u8fd0\u884c\u65f6\u7c7b\u578b\u3002<\/p>\n\n\n\n
8.10 Is a vs Has a, Interface vs Implementation<\/h1>\n\n\n
\n![\"\"](\"https:\/\/eve2333.top\/wp-content\/uploads\/2024\/11\/1731246462-\u5c4f\u5e55\u622a\u56fe-2024-11-10-213251-1024x541.png\")
<\/figure>\n<\/div>\n\n\n\u4e3a\u4e86\u603b\u7ed3\u8fd9\u6b21\u8bb2\u5ea7\uff0c\u8ba9\u6211\u4eec\u6bd4\u8f83\u4e00\u4e0b\u672c\u8bb2\u4e2d\u770b\u5230\u7684\u7ee7\u627f\u7c7b\u578b\u3002\u7b2c\u4e00\u79cd\u662f\u63a5\u53e3\u7ee7\u627f\uff0c\u6211\u559c\u6b22\u5b83\uff0c\u5b83\u662f\u4e2a\u4f1f\u5927\u7684\u60f3\u6cd5\uff0c\u5b83\u544a\u8bc9\u4f60\u53ef\u4ee5\u4ece\u5b50\u7c7b\u4e2d\u671f\u5f85\u4ec0\u4e48\uff0c\u6240\u4ee5\u8d85\u7c7b\u6216\u63a5\u53e3\u4f1a\u8bf4\u6240\u6709\u7684\u5217\u8868\u90fd\u5fc5\u987b\u505a\u8fd9\u4e9b\u4e8b\u60c5\uff0c\u5b83\u5141\u8bb8\u4f60\u4ee5\u4e00\u79cd\u5f3a\u5927\u800c\u7b80\u5355\u7684\u65b9\u5f0f\u6cdb\u5316\u4f60\u7684\u4ee3\u7801\u3002\u5982\u679c\u6211\u4eec\u770b\u770b`longest`\u65b9\u6cd5\u7684\u4f8b\u5b50\uff0c<\/p>\n\n\n\n
public static String longest(List61B<String>list){<\/code><\/pre>\n\n\n\n\u5b83\u9002\u7528\u4e8e\u4efb\u4f55\u5217\u8868\uff0c\u800c\u4e0d\u4ec5\u4ec5\u662f\u73b0\u6709\u7684\u5217\u8868\uff0c\u800c\u662f\u5c06\u6765\u4efb\u4f55\u65f6\u5019\u7f16\u5199\u7684\u5217\u8868\u3002\u6240\u4ee5\uff0c\u5982\u679c\u4e00\u5343\u5e74\u540e\u6709\u4eba\u6316\u51fa\u6211\u7684\u4ee3\u7801\uff0c\u50cf\u6211\u7684\u9aa8\u67b6\u8eba\u5728\u67d0\u4e2a\u5730\u65b9\u63e1\u7740\u4e00\u4e2aU\u76d8\uff0c\u4ed6\u4eec\u627e\u5230\u4e86\u8fd9\u4e2a\u4e1c\u897f\uff0c\u4ed6\u4eec\u4f1a\u8bf4\uff1a\u201c\u662f\u7684\uff0c\u8fd9\u5f88\u597d\u3002\u201d \u800c\u4e14\u4ed6\u4eec\u8bf4\uff1a\u201c\u55ef\uff0c\u6211\u4eec\u6ca1\u6709\u5217\u8868\u5b9e\u73b0\uff0c\u9664\u4e86\u8fd9\u4e2a\u5947\u602a\u7684\u961f\u5217\u5217\u8868\u4e4b\u5916\uff0c\u53ea\u8981\u5b83\u9075\u5b88`List61B`\u63a5\u53e3\uff0c\u4e0d\u7ba1\u5b83\u662f\u600e\u4e48\u505a\u7684\uff0c\u5b83\u4ecd\u7136\u4f1a\u5de5\u4f5c\u3002\u201d \u8fd9\u5f88\u597d\u3002<\/p>\n\n\n\n
\u8fd8\u6709\u53e6\u4e00\u79cd\u5b9e\u73b0\u7ee7\u627f\uff0c\u5b83\u544a\u8bc9\u4f60\u5b50\u7c7b\u5e94\u8be5\u5982\u4f55\u884c\u4e3a\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u201c\u8001\u677f\u201d\u544a\u8bc9\u4e0b\u5c5e\u4eec\u5177\u4f53\u5982\u4f55\u5b8c\u6210\u4ed6\u4eec\u7684\u5de5\u4f5c\u3002\u8fd9\u5f88\u597d\uff0c\u56e0\u4e3a\u201c\u8001\u677f\u201d\u53ef\u4ee5\u63d0\u4f9b\u4e00\u4e2a\u901a\u7528\u7684\u5de5\u4f5c`print`\u65b9\u6cd5\uff0c\u4efb\u4f55\u4eba\u90fd\u53ef\u4ee5\u4f7f\u7528\u3002\u6240\u4ee5\uff0c\u5982\u679c\u4f60\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u5217\u8868\u53eb\u505a\u961f\u5217\u5217\u8868\uff0c\u4f60\u4e0d\u786e\u5b9a\u5982\u4f55\u6253\u5370\uff0c\u81f3\u5c11\u4f60\u6709\u8fd9\u4e2a\u65b9\u6cd5\u53ef\u7528\u3002\u867d\u7136\u5b83\u53ef\u80fd\u4e0d\u662f\u6700\u6709\u6548\u7684\u65b9\u5f0f\uff0c\u4f46\u5b83\u5728\u90a3\u91cc\uff0c\u6240\u4ee5\u5b83\u7ed9\u4e86\u4f60\u989d\u5916\u7684\u63a7\u5236\u5c42\uff0c\u4f60\u53ef\u4ee5\u51b3\u5b9a\u662f\u5426\u8986\u5199\u5b83\uff0c\u8fd9\u53ef\u4ee5\u5f88\u597d\u3002<\/p>\n\n\n\n
\u5728\u8fd9\u4e24\u79cd\u60c5\u51b5\u4e0b\uff0c\u6211\u60f3\u6307\u51fa\u4e00\u4e2a\u5e38\u89c1\u7684\u9677\u9631\uff0c\u4f60\u53ef\u80fd\u4f1a\u6389\u8fdb\u8fd9\u4e2a\u9677\u9631\uff1a\u65e0\u8bba\u4f60\u4f7f\u7528\u54ea\u79cd\u7ee7\u627f\uff0c\u90fd\u5e94\u8be5\u6307\u5b9a\u4e00\u4e2a\u201cis-a\u201d\u5173\u7cfb\uff0c\u800c\u4e0d\u662f\u201chas-a\u201d\u5173\u7cfb\u3002<\/p>\n\n\n\n
\u6211\u662f\u4ec0\u4e48\u610f\u601d\u5462\uff1f\u4e00\u4e2a\u597d\u7684\u201cis-a\u201d\u5173\u7cfb\u7684\u4f8b\u5b50\u662f\uff1a\u72d7\u662f\u4e00\u79cd\u52a8\u7269\uff0c\u6ca1\u9519\uff0c\u6bcf\u53ea\u72d7\u90fd\u662f\u52a8\u7269\uff1b\u540c\u6837\uff0c\u6bcf\u4e2a`SList`\u90fd\u662f\u4e00\u4e2a`List61B`\uff0c\u8fd9\u5f88\u597d\uff0c\u6211\u4eec\u901a\u8fc7\u8fd9\u79cd\u65b9\u5f0f\u6307\u5b9a\u8fd9\u4e9b\u5173\u7cfb\u3002\u76f8\u6bd4\u4e4b\u4e0b\uff0c\u5982\u679c\u4f60\u8bfb\u4f5c\u201chas-a\u201d\uff0c\u90a3\u5c31\u4e0d\u597d\u4e86\uff0c\u4f60\u4e0d\u5e94\u8be5\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\u4f7f\u7528\u7ee7\u627f\u3002\u6240\u4ee5\uff0c\u4f8b\u5982\uff0c\u5982\u679c\u6211\u521b\u5efa\u4e00\u4e2a\u540d\u4e3a\u732b\u7684\u7c7b\uff0c\u5e76\u5b9e\u73b0\u722a\u5b50\uff0c\u786e\u5b9e\u732b\u6709\u722a\u5b50\uff0c\u4f46\u732b\u4e0d\u662f\u722a\u5b50\u3002\u4f60\u53ef\u80fd\u4f1a\u8bf4\u8fd9\u542c\u8d77\u6765\u5f88\u5947\u602a\uff0c\u6211\u4e3a\u4ec0\u4e48\u8981\u8fd9\u4e48\u505a\uff0c\u4f46\u8fd9\u91cc\u6709\u4e00\u4e2a\u66f4\u597d\u7684\u4f8b\u5b50\uff0c\u6216\u8bb8\u4f60\u80fd\u660e\u767d\u4e3a\u4ec0\u4e48\u4f60\u53ef\u80fd\u4f1a\u88ab\u8bf1\u60d1\u8d70\u5411\u9ed1\u6697\u9762\u3002\u5982\u679c\u6211\u8bf4\u96c6\u5408\u5b9e\u73b0\u4e86`SList`\uff0c\u6211\u5b9e\u9645\u4e0a\u8bd5\u56fe\u4f7f\u7528`SList`\u6765\u5b9e\u73b0\u4e00\u4e2a\u96c6\u5408\uff0c\u96c6\u5408\u662f\u4e00\u4e2a\u4e0d\u5141\u8bb8\u91cd\u590d\u5143\u7d20\u7684\u5bf9\u8c61\u96c6\u5408\u3002\u4f8b\u5982\uff0c\u5982\u679c\u6211\u8c03\u7528`AB.first(\"potato\")`\u4e09\u6b21\uff0c\u96c6\u5408\u4e2d\u53ea\u4f1a\u6709\u4e00\u4e2a\u571f\u8c46\u3002\u4f60\u53ef\u4ee5\u60f3\u8c61\u5c1d\u8bd5\u8986\u5199`SList`\u7684\u65b9\u6cd5\u6765\u6355\u6349\u8fd9\u79cd\u884c\u4e3a\uff0c\u4e0d\u7ba1\u5b83\u662f\u4ec0\u4e48\uff0c\u5b9e\u9645\u4e0a\u6211\u4eec\u4f1a\u628a`SList`\u626d\u66f2\u6210\u4e00\u4e2a\u96c6\u5408\uff0c\u4f46\u8fd9\u4e0d\u4f1a\u6309\u4f60\u60f3\u8981\u7684\u65b9\u5f0f\u5de5\u4f5c\uff0c\u6700\u7ec8\u4f1a\u53d8\u5f97\u975e\u5e38\u590d\u6742\u3002<\/p>\n\n\n\n
\u6240\u4ee5\uff0c\u4f7f\u7528\u63a5\u53e3\u6216\u5b9e\u73b0\u7ee7\u627f\u6765\u6355\u6349\u201chas-a\u201d\u5173\u7cfb\u7684\u8bf1\u60d1\uff0c\u8bf7\u907f\u514d\u8fd9\u6837\u505a\u3002\u987a\u4fbf\u8bf4\u4e00\u53e5\uff0c\u5b9e\u9645\u4e0a\u6211\u8fd8\u60f3\u591a\u8c08\u4e00\u70b9\u6211\u5bf9\u5b9e\u73b0\u7ee7\u627f\u7684\u4e00\u4e9b\u6000\u7591\uff0c\u4ee5\u53ca\u4e3a\u4ec0\u4e48\u5b83\u53ef\u80fd\u4f1a\u7ed9\u4f60\u5e26\u6765\u9ebb\u70e6\u7684\u539f\u56e0\u3002<\/p>\n\n\n\n
The Dangers of Implementation Inheritance<\/strong>
Particular Dangers of Implementation Inheritance<\/p>\n\n\n\n- \n
- Makes it harder to keep track of where something was actually implemented(though a good IDE makes this better).<\/li>\n\n\n\n
- Rules for resolving conflicts can be arcane. Won't cover in 61B.
\u00a0 \u00a0 \u00a0 \u00a0Example: What if two interfaces both give conflicting default methods?<\/li>\n\n\n\n - Encourages overly complex code(especially with novices).
\u00a0 \u00a0 \u00a0 \u00a0Common mistake: Has-a vs. Is-a!<\/li>\n\n\n\n - Breaks encapsulation!
\u00a0 \u00a0 \u00a0 \u00a0What is encapsulation? See next week.\u00a0<\/li>\n<\/ol>\n\n\n\n\u4e00\u4e2a\u6709\u65f6\u9002\u7528\u7684\u95ee\u9898\u662f\uff0c\u5b83\u53ef\u80fd\u5f88\u96be\u8ddf\u8e2a\u67d0\u4ef6\u4e8b\u60c5\u5b9e\u9645\u5728\u54ea\u91cc\u5b9e\u73b0\u3002\u60f3\u8c61\u4f60\u6709\u4e00\u4e2a\u6df1\u8fbe\u516d\u4e03\u5c42\u7684\u5b9e\u73b0\u5806\u6808\uff0c\u6bd4\u5982\u6211\u6709\u4e00\u4e2a\u52a8\u7269\u63a5\u53e3\uff0c\u7136\u540e\u6211\u6709\u98df\u8089\u52a8\u7269\uff0c\u7136\u540e\u662f\u54fa\u4e73\u52a8\u7269\uff0c\u7136\u540e\u662f\u72d7\u7b49\u7b49\u3002\u6f5c\u5728\u5730\u5f88\u96be\u8ddf\u8e2a\u54ea\u4e9b\u5730\u65b9\u88ab\u8986\u5199\u4e86\uff0c\u54ea\u4e9b\u5730\u65b9\u88ab\u5b9a\u4e49\u4e86\u7b49\u7b49\u3002\u4e00\u4e2a\u597d\u7684IDE\u4f7f\u8fd9\u51e0\u4e4e\u4e0d\u6210\u95ee\u9898\uff0c\u4f46\u4e5f\u610f\u5473\u7740\u4e00\u4e9b\u989d\u5916\u7684\u590d\u6742\u6027\u3002\u6709\u65f6\u5019\u4f60\u53ef\u80fd\u4f1a\u9047\u5230\u5947\u602a\u7684\u51b2\u7a81\uff0c\u60f3\u8c61\u4f60\u6709\u4e00\u4e2a\u670d\u52a1\u548c\u670d\u52a1\u52a9\u624b\uff0c\u5b83\u4eec\u90fd\u8bf4\u6709\u4e00\u4e2a\u52a9\u624b\u63a5\u53e3\u548c\u4e00\u4e2a\u52a8\u7269\u63a5\u53e3\uff0c\u7136\u540e\u4f60\u60f3\u5236\u4f5c\u4e00\u4e2a\u670d\u52a1\u72ac\u7c7b\uff0c\u5b9e\u73b0\u8fd9\u4e24\u4e2a\u8d85\u7c7b\u6216\u63a5\u53e3\u4e2d\u7684\u67d0\u4e9b\u4e1c\u897f\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u5982\u679c\u8fd9\u4e24\u4e2a\u63a5\u53e3\u4e4b\u95f4\u6709\u51b2\u7a81\uff0c\u4e5f\u8bb8\u5b83\u4eec\u90fd\u6709\u76f8\u540c\u7684\u4e00\u4e2a\u9ed8\u8ba4\u65b9\u6cd5\uff0c\u6709\u4e00\u4e9b\u590d\u6742\u7684\u89c4\u5219\u6765\u89e3\u51b3\u8fd9\u4e9b\u51b2\u7a81\uff0c\u5728Java\u4e2d\u901a\u5e38\u4e0d\u662f\u4ec0\u4e48\u5927\u95ee\u9898\uff0c\u4f46\u8fd9\u662f\u5b9e\u73b0\u7ee7\u627f\u7684\u4e00\u4e2a\u4e0d\u592a\u597d\u770b\u7684\u5730\u65b9\u3002<\/p>\n\n\n\n
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\u6211\u4e0d\u662f\u8bf4\u5b9e\u73b0\u7ee7\u627f\u4e0d\u597d\uff0c\u6211\u7684\u610f\u601d\u662f\u5b83\u662f\u4e00\u4e2a\u6781\u597d\u7684\u5de5\u5177\uff0c\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b83\u53ef\u4ee5\u8282\u7701\u5927\u91cf\u7684\u65f6\u95f4\uff0c\u800c\u4e14\u53ef\u4ee5\u975e\u5e38\u7f8e\u597d\u3002\u4f46\u4e0e\u5bf9\u6211\u6765\u8bf4\u662f\u660e\u663ewin\u7684\u63a5\u53e3\u7ee7\u627f\u4e0d\u540c\uff0c\u5b9e\u73b0\u7ee7\u627f\u53ef\u80fd\u6709\u70b9\u4e0d\u7a33\u5b9a\u3002\u597d\u4e86\uff0c\u8fd9\u5c31\u662f\u8fd9\u6b21\u8bb2\u5ea7\u7684\u5185\u5bb9\uff0c\u4e0b\u6b21\u89c1\u3002 \u200b<\/p>\n","protected":false},"excerpt":{"rendered":"
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- Note: If there are multiple methods that can handle T1, the compiler records the \"most specific\" one. For example, if T1=Dog, and TPrime has bar(Dog) and bar(Animal), it wil record bar(Dog).<\/li>\n<\/ul>\n\n\n\n
- Example: Let's add a default print() method to List61B.java\u00a0<\/li>\n<\/ul>\n\n\n\n