{"id":2286,"date":"2025-03-03T23:29:47","date_gmt":"2025-03-03T15:29:47","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=2286"},"modified":"2025-03-03T23:29:47","modified_gmt":"2025-03-03T15:29:47","slug":"java-8%e6%96%b0%e7%89%b9%e6%80%a7","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/03\/03\/java-8%e6%96%b0%e7%89%b9%e6%80%a7\/","title":{"rendered":"Java 8\u65b0\u7279\u6027"},"content":{"rendered":"\n

Java 8 \u5f15\u5165\u4e86\u4e00\u4e9b\u975e\u5e38\u91cd\u8981\u7684\u65b0\u7279\u6027\uff0c\u4f7f\u5f97 Java \u7f16\u7a0b\u53d8\u5f97\u66f4\u52a0\u7b80\u6d01\u3001\u7075\u6d3b\u548c\u529f\u80fd\u5f3a\u5927\u3002\u4ee5\u4e0b\u662f Java 8 \u7684\u51e0\u4e2a\u4e3b\u8981\u65b0\u7279\u6027\uff1a<\/p>\n\n\n\n

1. Lambda \u8868\u8fbe\u5f0f<\/strong><\/h3>\n\n\n\n

Lambda \u8868\u8fbe\u5f0f\u662f Java 8 \u6700\u5177\u6807\u5fd7\u6027\u7684\u7279\u6027\u4e4b\u4e00\uff0c\u5b83\u4f7f\u5f97 Java \u7a0b\u5e8f\u53ef\u4ee5\u50cf\u51fd\u6570\u5f0f\u7f16\u7a0b\u8bed\u8a00\u4e00\u6837\u5904\u7406\u4ee3\u7801\u3002Lambda \u8868\u8fbe\u5f0f\u5141\u8bb8\u4f60\u5c06\u4ee3\u7801\u5757\u4f5c\u4e3a\u53c2\u6570\u4f20\u9012\u7ed9\u65b9\u6cd5\uff0c\u6216\u8005\u5c06\u5176\u5b58\u50a8\u4e3a\u53d8\u91cf\u3002<\/p>\n\n\n\n

\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n

import java.util.*;\n\npublic class LambdaExample {\n    public static void main(String[] args) {\n        List<String> list = Arrays.asList(\"Apple\", \"Banana\", \"Cherry\");\n\n        \/\/ \u4f7f\u7528 Lambda \u8868\u8fbe\u5f0f\u904d\u5386\u96c6\u5408\n        list.forEach(item -> System.out.println(item));\n    }\n}<\/code><\/pre>\n\n\n\n
\u4e0a\u8ff0\u4ee3\u7801\u4f7f\u7528 Lambda \u8868\u8fbe\u5f0f\u6765\u904d\u5386\u4e00\u4e2a\u96c6\u5408\uff0c\u5e76\u6253\u5370\u6bcf\u4e2a\u5143\u7d20\u3002<\/p>\n\n\n\n
2. \u51fd\u6570\u5f0f\u63a5\u53e3<\/strong><\/h3>\n\n\n\n
\u51fd\u6570\u5f0f\u63a5\u53e3\u662f\u53ea\u6709\u4e00\u4e2a\u62bd\u8c61\u65b9\u6cd5\u7684\u63a5\u53e3\u3002Lambda \u8868\u8fbe\u5f0f\u548c\u65b9\u6cd5\u5f15\u7528\u7684\u76ee\u6807\u7c7b\u578b\u662f\u51fd\u6570\u5f0f\u63a5\u53e3\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
@FunctionalInterface\npublic interface MyFunctionalInterface {\n    void apply(int x, int y);\n}<\/code><\/pre>\n\n\n\n
\u4f7f\u7528 Lambda \u8868\u8fbe\u5f0f\uff1a<\/strong><\/p>\n\n\n\n
MyFunctionalInterface myFunc = (x, y) -> System.out.println(x + y);\nmyFunc.apply(5, 10);  \/\/ \u8f93\u51fa: 15<\/code><\/pre>\n\n\n\n
3. Stream API<\/strong><\/h3>\n\n\n\n
Stream API \u662f Java 8 \u5f15\u5165\u7684\u4e00\u4e2a\u65b0\u5e93\uff0c\u4f7f\u5f97\u96c6\u5408\u64cd\u4f5c\uff08\u5982\u8fc7\u6ee4\u3001\u6392\u5e8f\u3001\u6620\u5c04\u7b49\uff09\u53d8\u5f97\u66f4\u52a0\u7b80\u6d01\u548c\u51fd\u6570\u5f0f\u3002Stream API \u652f\u6301\u5e76\u884c\u5904\u7406\uff0c\u6781\u5927\u5730\u63d0\u5347\u4e86\u6027\u80fd\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
import java.util.*;\nimport java.util.stream.*;\n\npublic class StreamExample {\n    public static void main(String[] args) {\n        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);\n\n        \/\/ \u4f7f\u7528 Stream API \u8fdb\u884c\u7b5b\u9009\u548c\u6620\u5c04\n        List<Integer> evenNumbers = numbers.stream()\n                                           .filter(n -> n % 2 == 0)\n                                           .map(n -> n * 2)\n                                           .collect(Collectors.toList());\n\n        System.out.println(evenNumbers);  \/\/ \u8f93\u51fa: [4, 8, 12, 16, 20]\n    }\n}<\/code><\/pre>\n\n\n\n
4. \u9ed8\u8ba4\u65b9\u6cd5\uff08Default Methods\uff09<\/strong><\/h3>\n\n\n\n
\u9ed8\u8ba4\u65b9\u6cd5\u4f7f\u5f97\u63a5\u53e3\u53ef\u4ee5\u6709\u65b9\u6cd5\u7684\u5b9e\u73b0\uff0c\u800c\u4e0d\u9700\u8981\u5728\u6bcf\u4e2a\u5b9e\u73b0\u7c7b\u4e2d\u8fdb\u884c\u5b9e\u73b0\u3002\u8fd9\u6837\u53ef\u4ee5\u5728\u4e0d\u7834\u574f\u73b0\u6709\u63a5\u53e3\u7684\u60c5\u51b5\u4e0b\uff0c\u5411\u63a5\u53e3\u6dfb\u52a0\u65b0\u529f\u80fd\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
public interface MyInterface {\n    \/\/ \u9ed8\u8ba4\u65b9\u6cd5\n    default void defaultMethod() {\n        System.out.println(\"\u8fd9\u662f\u4e00\u4e2a\u9ed8\u8ba4\u65b9\u6cd5\");\n    }\n\n    void abstractMethod();\n}\n\npublic class MyClass implements MyInterface {\n    @Override\n    public void abstractMethod() {\n        System.out.println(\"\u8fd9\u662f\u62bd\u8c61\u65b9\u6cd5\u7684\u5b9e\u73b0\");\n    }\n}\n\npublic class Main {\n    public static void main(String[] args) {\n        MyClass obj = new MyClass();\n        obj.abstractMethod();    \/\/ \u8f93\u51fa: \u8fd9\u662f\u62bd\u8c61\u65b9\u6cd5\u7684\u5b9e\u73b0\n        obj.defaultMethod();     \/\/ \u8f93\u51fa: \u8fd9\u662f\u4e00\u4e2a\u9ed8\u8ba4\u65b9\u6cd5\n    }\n}<\/code><\/pre>\n\n\n\n
5. \u65b9\u6cd5\u5f15\u7528 (Method References)<\/strong><\/h3>\n\n\n\n
\u65b9\u6cd5\u5f15\u7528\u662f Lambda \u8868\u8fbe\u5f0f\u7684\u4e00\u79cd\u7b80\u5199\u65b9\u5f0f\uff0c\u5b83\u5141\u8bb8\u76f4\u63a5\u5f15\u7528\u7c7b\u6216\u5b9e\u4f8b\u7684\u65b9\u6cd5\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
import java.util.*;\n\npublic class MethodReferenceExample {\n    public static void main(String[] args) {\n        List<String> list = Arrays.asList(\"apple\", \"banana\", \"cherry\");\n\n        \/\/ \u4f7f\u7528\u65b9\u6cd5\u5f15\u7528\u6765\u66ff\u4ee3 Lambda \u8868\u8fbe\u5f0f\n        list.forEach(System.out::println);\n    }\n}<\/code><\/pre>\n\n\n\n
\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cSystem.out::println<\/code> \u5c31\u662f\u65b9\u6cd5\u5f15\u7528\uff0c\u76f8\u5f53\u4e8e item -> System.out.println(item)<\/code>\u3002<\/p>\n\n\n\n
6. Optional \u7c7b<\/strong><\/h3>\n\n\n\n
Optional<\/code> \u662f Java 8 \u5f15\u5165\u7684\u4e00\u4e2a\u5bb9\u5668\u7c7b\uff0c\u5b83\u7528\u4e8e\u8868\u793a\u53ef\u80fd\u4e3a\u7a7a\u7684\u503c\u3002\u5b83\u662f\u907f\u514d\u7a7a\u6307\u9488\u5f02\u5e38\uff08NullPointerException\uff09\u7684\u4e00\u4e2a\u91cd\u8981\u5de5\u5177\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
import java.util.Optional;\n\npublic class OptionalExample {\n    public static void main(String[] args) {\n        Optional<String> nonEmpty = Optional.of(\"Hello\");\n        Optional<String> empty = Optional.empty();\n\n        \/\/ \u5224\u65ad\u662f\u5426\u6709\u503c\n        System.out.println(nonEmpty.isPresent());  \/\/ \u8f93\u51fa: true\n        System.out.println(empty.isPresent());     \/\/ \u8f93\u51fa: false\n\n        \/\/ \u83b7\u53d6\u503c\n        System.out.println(nonEmpty.get());  \/\/ \u8f93\u51fa: Hello\n    }\n}<\/code><\/pre>\n\n\n\n
7. \u65b0\u7684\u65e5\u671f\u65f6\u95f4 API\uff08java.time\uff09<\/strong><\/h3>\n\n\n\n
Java 8 \u5f15\u5165\u4e86\u5168\u65b0\u7684\u65e5\u671f\u548c\u65f6\u95f4 API\uff0c\u4f4d\u4e8e java.time<\/code> \u5305\u4e0b\u3002\u5b83\u89e3\u51b3\u4e86 java.util.Date<\/code> \u548c java.util.Calendar<\/code> \u7684\u4e00\u4e9b\u4e0d\u8db3\uff0c\u5177\u6709\u66f4\u9ad8\u7684\u53ef\u8bfb\u6027\u548c\u66f4\u597d\u7684\u65f6\u95f4\u64cd\u4f5c\u529f\u80fd\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
import java.time.LocalDate;\nimport java.time.LocalTime;\nimport java.time.LocalDateTime;\n\npublic class DateTimeExample {\n    public static void main(String[] args) {\n        LocalDate date = LocalDate.now();\n        LocalTime time = LocalTime.now();\n        LocalDateTime dateTime = LocalDateTime.now();\n\n        System.out.println(\"\u5f53\u524d\u65e5\u671f: \" + date);\n        System.out.println(\"\u5f53\u524d\u65f6\u95f4: \" + time);\n        System.out.println(\"\u5f53\u524d\u65e5\u671f\u65f6\u95f4: \" + dateTime);\n    }\n}<\/code><\/pre>\n\n\n\n
8. Nashorn JavaScript \u5f15\u64ce<\/strong><\/h3>\n\n\n\n
Java 8 \u5f15\u5165\u4e86 Nashorn<\/code> JavaScript \u5f15\u64ce\uff0c\u5b83\u5141\u8bb8\u5728 Java \u4e2d\u76f4\u63a5\u8fd0\u884c JavaScript \u4ee3\u7801\uff0c\u6bd4\u539f\u6765\u7684 Rhino \u5f15\u64ce\u6027\u80fd\u66f4\u597d\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
import javax.script.*;\n\npublic class NashornExample {\n    public static void main(String[] args) throws ScriptException {\n        ScriptEngine engine = new ScriptEngineManager().getEngineByName(\"nashorn\");\n\n        \/\/ \u6267\u884c JavaScript \u4ee3\u7801\n        engine.eval(\"print('Hello, Nashorn!')\");\n    }\n}<\/code><\/pre>\n\n\n\n
9. \u91cd\u590d\u6ce8\u89e3<\/strong><\/h3>\n\n\n\n
Java 8 \u5141\u8bb8\u5728\u540c\u4e00\u4ee3\u7801\u5143\u7d20\u4e0a\u4f7f\u7528\u591a\u4e2a\u76f8\u540c\u7684\u6ce8\u89e3\uff0c\u8fd9\u5bf9\u4e8e\u4f7f\u7528\u6846\u67b6\u65f6\u7279\u522b\u6709\u7528\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
import java.lang.annotation.*;\n\n@Retention(RetentionPolicy.RUNTIME)\n@Target(ElementType.METHOD)\npublic @interface MyAnnotation {\n    String value();\n}\n\npublic class MyClass {\n    @MyAnnotation(\"Hello\")\n    @MyAnnotation(\"World\")\n    public void myMethod() {}\n}<\/code><\/pre>\n\n\n\n
10. Parallel Streams<\/strong><\/h3>\n\n\n\n
Java 8 \u7684 Stream API \u652f\u6301\u5e76\u884c\u64cd\u4f5c\uff0c\u4f7f\u5f97\u4f60\u53ef\u4ee5\u8f7b\u677e\u5b9e\u73b0\u5e76\u884c\u5904\u7406\uff0c\u4ece\u800c\u63d0\u9ad8\u6027\u80fd\u3002<\/p>\n\n\n\n
\u793a\u4f8b\uff1a<\/strong><\/p>\n\n\n\n
import java.util.*;\nimport java.util.stream.*;\n\npublic class ParallelStreamExample {\n    public static void main(String[] args) {\n        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);\n\n        \/\/ \u4f7f\u7528\u5e76\u884c\u6d41\u6765\u52a0\u901f\u5904\u7406\n        int sum = numbers.parallelStream().mapToInt(Integer::intValue).sum();\n        System.out.println(\"\u603b\u548c: \" + sum);\n    }\n}<\/code><\/pre>\n\n\n\n
\u603b\u7ed3<\/strong><\/h3>\n\n\n\n
Java 8 \u5f15\u5165\u4e86\u5927\u91cf\u65b0\u7279\u6027\uff0c\u4f7f\u5f97 Java \u7f16\u7a0b\u66f4\u52a0\u7075\u6d3b\u548c\u5f3a\u5927\uff0c\u5c24\u5176\u662f\u5728\u51fd\u6570\u5f0f\u7f16\u7a0b\u548c\u5e76\u884c\u5904\u7406\u65b9\u9762\u3002\u4f60\u53ef\u4ee5\u901a\u8fc7 Lambda \u8868\u8fbe\u5f0f\u3001Stream API\u3001\u9ed8\u8ba4\u65b9\u6cd5\u7b49\u5927\u5927\u7b80\u5316\u4ee3\u7801\uff0c\u540c\u65f6\u63d0\u5347\u6027\u80fd\u3002<\/p>\n\n\n\n
\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
Java 8 \u5f15\u5165\u4e86\u4e00\u4e9b\u975e\u5e38\u91cd\u8981\u7684\u65b0\u7279\u6027\uff0c\u4f7f\u5f97 Java \u7f16\u7a0b\u53d8\u5f97\u66f4\u52a0\u7b80\u6d01\u3001\u7075\u6d3b\u548c\u529f\u80fd\u5f3a\u5927\u3002\u4ee5\u4e0b\u662f Java  […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[68],"tags":[],"class_list":["post-2286","post","type-post","status-publish","format-standard","hentry","category-java"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2286","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=2286"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2286\/revisions"}],"predecessor-version":[{"id":2287,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2286\/revisions\/2287"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=2286"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=2286"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=2286"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}