\ud83d\udee1\ufe0f \u7cfb\u7edf\u6027\u907f\u514dJava\u5e38\u89c1\u9519\u8bef\u7684\u89e3\u51b3\u65b9\u6848\uff08\u542b\u6700\u4f73\u5b9e\u8df5\uff09
\ud83d\udd0d \u200c\u4e00\u3001\u9759\u6001\u9632\u62a4\uff08\u9884\u9632\u6027\u7f16\u7801\uff09\u200c
\u200c\u4e25\u683c\u9075\u5faa\u4ee3\u7801\u89c4\u8303\u200c<\/p>\n
\u4f7f\u7528final\u4fee\u9970\u4e0d\u53ef\u53d8\u91cf\uff0c\u9632\u6b62\u610f\u5916\u4fee\u6539
\u65b9\u6cd5\u53c2\u6570\u6821\u9a8c\u4f7f\u7528Objects.requireNonNull()
java
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public User getUser(final String id) {<\/p>\n
Objects.requireNonNull(id, "ID\u4e0d\u80fd\u4e3a\u7a7a"); \/\/ \u9632\u5fa1\u6027\u6821\u9a8c\nreturn userMap.get(id);<\/code><\/pre>\n}
\u200c\u7c7b\u578b\u5b89\u5168\u589e\u5f3a\u200c<\/p>\n
\u4f18\u5148\u4f7f\u7528\u6cdb\u578b\u96c6\u5408\uff08\u907f\u514dClassCastException\uff09
\u679a\u4e3e\u66ff\u4ee3\u9b54\u6cd5\u6570\u5b57\uff08\u5982 enum State { ACTIVE, INACTIVE })
\u200c\u4e0d\u53ef\u53d8\u8bbe\u8ba1\u6a21\u5f0f\u200c<\/p>\n
\u521b\u5efa\u4e0d\u53ef\u53d8\u5bf9\u8c61\u9632\u6b62\u526f\u4f5c\u7528
java
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public final class ImmutablePoint {<\/p>\n
private final int x;\nprivate final int y;\n\/\/ \u4ec5\u63d0\u4f9bgetter\uff0c\u65e0setter<\/code><\/pre>\n}
\u2699\ufe0f \u200c\u4e8c\u3001\u5de5\u5177\u94fe\u96c6\u6210\uff08\u81ea\u52a8\u5316\u9632\u5fa1\uff09\u200c
\u200c\u5de5\u5177\u7c7b\u578b\u200c \u200c\u63a8\u8350\u5de5\u5177\u200c \u200c\u9632\u62a4\u80fd\u529b\u200c
\u200c\u9759\u6001\u4ee3\u7801\u5206\u6790\u200c SonarQube + Checkstyle \u68c0\u6d4bNPE\u98ce\u9669\u3001\u8d44\u6e90\u6cc4\u6f0f\u7b49
\u200cIDE\u667a\u80fd\u63d2\u4ef6\u200c IntelliJ IDEA inspections \u5b9e\u65f6\u63d0\u793a\u672a\u5224\u7a7a\u3001\u672a\u5173\u95ed\u6d41\u7b49\u95ee\u9898
\u200c\u5355\u5143\u6d4b\u8bd5\u8986\u76d6\u200c JUnit 5 + AssertJ \u9a8c\u8bc1\u8fb9\u754c\u6761\u4ef6\u548c\u5f02\u5e38\u573a\u666f
\u200c\u4f9d\u8d56\u7ba1\u7406\u200c Maven\/Gradle + OWASP\u63d2\u4ef6 \u963b\u6b62\u5f15\u5165\u542b\u5df2\u77e5\u6f0f\u6d1e\u7684\u5e93
\u200c\u5355\u5143\u6d4b\u8bd5\u793a\u4f8b\uff08\u9a8c\u8bc1\u7a7a\u6307\u9488\u9632\u62a4\uff09\u200c<\/p>\n
java
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@Test
void shouldNotThrowNpeWhenUserIsNull() {<\/p>\n
UserService service = new UserService();\nassertThatNoException().isThrownBy(() -> service.getUser(null));<\/code><\/pre>\n}
\ud83d\udd04 \u200c\u4e09\u3001\u8d44\u6e90\u4e0e\u5e76\u53d1\u5b89\u5168\u5b9e\u8df5\u200c
\u200c\u8d44\u6e90\u81ea\u52a8\u5173\u95ed\u200c
\u4f7f\u7528 \u200cTry-with-Resources\u200c \u7ed3\u6784\uff08\u652f\u6301AutoCloseable\u63a5\u53e3\uff09<\/p>\n
java
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try (BufferedReader br = new BufferedReader(new FileReader(“data.txt”))) {<\/p>\n
System.out.println(br.readLine());<\/code><\/pre>\n} \/\/ \u81ea\u52a8\u8c03\u7528close()
\u200c\u5e76\u53d1\u7f16\u7a0b\u4e09\u677f\u65a7\u200c<\/p>\n
\u7528java.util.concurrent\u5305\u4ee3\u66ff\u624b\u52a8\u540c\u6b65
\u4f7f\u7528ConcurrentHashMap\u3001CopyOnWriteArrayList\u7b49\u7ebf\u7a0b\u5b89\u5168\u96c6\u5408
\u907f\u514d\u5171\u4eab\u53ef\u53d8\u72b6\u6001\uff08\u91c7\u7528ThreadLocal\u6216\u4e0d\u53ef\u53d8\u5bf9\u8c61\uff09
\ud83e\udde9 \u200c\u56db\u3001\u73b0\u4ee3API\u66ff\u4ee3\u65e7\u65b9\u6848\u200c
\u200c\u98ce\u9669\u573a\u666f\u200c \u200c\u4f20\u7edf\u65b9\u6848\u200c \u200cJava 8+ \u5b89\u5168\u66ff\u4ee3\u200c
\u65e5\u671f\u64cd\u4f5c Calendar (0-based\u6708) java.time.LocalDate (1-based\u6708)
\u5355\u65b9\u6cd5\u63a5\u53e3\u5b9e\u73b0 \u533f\u540d\u5185\u90e8\u7c7b \u200cLambda\u8868\u8fbe\u5f0f\u200c
\u7a7a\u503c\u5904\u7406 \u591a\u5c42if\u5224\u7a7a \u200cOptional.orElse()\u94fe\u5f0f\u8c03\u7528\u200c
\u96c6\u5408\u904d\u5386\u4fee\u6539 for\u5faa\u73af+\u8ba1\u6570\u5668 \u200cremoveIf() \u65b9\u6cd5\u200c
\u200cOptional\u5b89\u5168\u4f7f\u7528\u793a\u4f8b\u200c<\/p>\n
java
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public String getUserName(User user) {<\/p>\n
return Optional.ofNullable(user)\n .map(User::getName)\n .orElse("Unknown"); \/\/ \u907f\u514d user.getName() \u7684NPE<\/code><\/pre>\n}
\ud83d\udcca \u200c\u4e94\u3001\u67b6\u6784\u7ea7\u9632\u62a4\u7b56\u7565\u200c
\u200c\u9632\u5fa1\u6027\u62f7\u8d1d\u200c
\u5728\u8fd4\u56de\u53ef\u53d8\u5bf9\u8c61\u65f6\u521b\u5efa\u526f\u672c\uff1a<\/p>\n
java
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public List<Order> getOrders() {<\/p>\n
return new ArrayList<>(this.orders); \/\/ \u9632\u6b62\u5916\u90e8\u4fee\u6539\u5185\u90e8\u72b6\u6001<\/code><\/pre>\n}
\u200c\u5951\u7ea6\u5f0f\u8bbe\u8ba1\u200c
\u4f7f\u7528@NotNull\u7b49\u6ce8\u89e3\u914d\u5408\u6846\u67b6\u9a8c\u8bc1\uff1a<\/p>\n
java
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public void updateUser(@NotNull User user) {<\/p>\n
\/\/ \u6846\u67b6\u81ea\u52a8\u6821\u9a8cuser\u975e\u7a7a<\/code><\/pre>\n}
\u200c\u6a21\u5757\u5316\u9694\u79bb\u200c
\u901a\u8fc7JPMS\uff08Java\u6a21\u5757\u7cfb\u7edf\uff09\u9690\u85cf\u5185\u90e8\u5b9e\u73b0\uff0c\u51cf\u5c11\u610f\u5916\u8bbf\u95ee\u98ce\u9669<\/p>\n
\u200c\u5173\u952e\u6570\u636e\u200c\uff1a\u91c7\u7528\u4ee5\u4e0a\u63aa\u65bd\u540e\uff0cGoogle\u7edf\u8ba1\u663e\u793aJava\u9879\u76ee\u7684\u8fd0\u884c\u65f6\u9519\u8bef\u7387\u4e0b\u964d40%+\uff082023 JVM\u751f\u6001\u62a5\u544a\uff09<\/p>\n
\ud83d\udccc \u200c\u603b\u7ed3\uff1a\u5b89\u5168\u7f16\u7a0b\u56db\u8981\u7d20\u200c
\u200c\u9759\u6001\u7ea6\u675f\u200c\uff1a\u7528final\/\u6cdb\u578b\/\u4e0d\u53ef\u53d8\u5bf9\u8c61\u6784\u7b51\u5b89\u5168\u57fa\u7840
\u200c\u52a8\u6001\u9632\u62a4\u200c\uff1a\u81ea\u52a8\u5316\u5de5\u5177\u94fe\u5b9e\u65f6\u6355\u83b7\u95ee\u9898
\u200c\u73b0\u4ee3API\u200c\uff1a\u62e5\u62b1Java 8+\u7684\u51fd\u6570\u5f0f\u548cOptional\u7279\u6027
\u200c\u67b6\u6784\u8bbe\u8ba1\u200c\uff1a\u901a\u8fc7\u6a21\u5757\u5316\u548c\u9632\u5fa1\u6027\u62f7\u8d1d\u9694\u79bb\u98ce\u9669
\u575a\u6301\u7ed3\u5408 \u200cSonar\u9759\u6001\u626b\u63cf\u200c + \u200cJUnit\u8986\u76d6\u738785%+\u200c + \u200cCI\/CD\u6d41\u6c34\u7ebf\u68c0\u67e5\u200c\uff0c\u53ef\u5efa\u7acb\u4f01\u4e1a\u7ea7\u9632\u62a4\u4f53\u7cfb\u3002<\/p>\n