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一、Lambda表达式 Lambda 是一个匿名函数。可以写出更简洁、更灵活的代码。作为一种更紧凑的代码风格，使Java的语言表达能力得到了提升。
1.1、Lambda表达式的关键：从匿名类到 Lambda 的转换
示例：
span style=background-color:#…参考书籍：《Java8 实战》
一、Lambda表达式 Lambda 是一个匿名函数。可以写出更简洁、更灵活的代码。作为一种更紧凑的代码风格，使Java的语言表达能力得到了提升。
1.1、Lambda表达式的关键：从匿名类到 Lambda 的转换
示例：
span style="background-color:#f8f8f8"span style="color:#333333" span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"void/span span style="color:#000000"main/span(span style="color:#000000"String/span[] span style="color:#000000"args/span) { span style="color:#aa5500"//创建线程--匿名类写法/span span style="color:#000000"Thread/span span style="color:#000000"td/span span style="color:#981a1a"=/span span style="color:#221199"new/span span style="color:#000000"Thread/span(span style="color:#221199"new/span span style="color:#000000"Runnable/span() { span style="color:#000000"@Override/span span style="color:#000000"public/span span style="color:#000000"void/span span style="color:#000000"run/span() { span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#aa1111""hello,Lamada!"/span); } }); span style="color:#000000"td/spanspan style="color:#116644"./spanspan style="color:#000000"start/span(); span style="color:#aa5500"//lamada写法--面向函数式编程(匿名函数)/span span style="color:#000000"Thread/span span style="color:#000000"td1/span span style="color:#981a1a"=/span span style="color:#221199"new/span span style="color:#000000"Thread/span(() span style="color:#981a1a"-/span span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#aa1111""hello,Lamada01!"/span)); span style="color:#000000"td1/spanspan style="color:#116644"./spanspan style="color:#000000"start/span(); }/span/span
1.2、Lambda表达式语法 Lambda表达式在Java 语言中引入了一个新的语法元素和操作符。这个操作符为 “-” ， 该操作符被称 为 Lambda 操作符或箭头操作符。它将 Lambda 分为两个部分： 左侧： 指定了 Lambda 表达式需要的所有参数 右侧： 指定了 Lambda 体，即 Lambda 表达式要执行的功能。 （1）语法格式一：无参，无返回值，Lambda 体只需一条语句 示例：Runnable r1 = () - System.out.println("Hello Lambda!"); （2）语法格式二：Lambda 需要一个参数 示例：ConsumerString con = （x） - System.out.println(x); （3）语法格式三：Lambda 只需要一个参数时，参数的小括号可以省略 示例：ConsumerString con = x - System.out.println(x); （4）语法格式四：Lambda 需要两个参数，并且有返回值 示例：
span style="background-color:#f8f8f8"span style="color:#333333"span style="color:#000000"Comparator/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/spanspan style="color:#981a1a"/span span style="color:#000000"com/span span style="color:#981a1a"=/span (span style="color:#000000"x/span, span style="color:#000000"y/span) span style="color:#981a1a"-/span { span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#aa1111""函数式接口"/span); span style="color:#770088"return/span span style="color:#000000"Integer/spanspan style="color:#116644"./spanspan style="color:#000000"compare/span(span style="color:#000000"x/span, span style="color:#000000"y/span);};/span/span
（5）语法格式五：当 Lambda 体只有一条语句时，return 与大括号可以省略 示例：ComparatorInteger com = (x, y) - Integer.compare(x, y); （6）Lambda 表达式的参数列表的数据类型可以省略不写，因为JVM编译器通过上下文推断出，数据类型，即“类型推断” 示例：
span style="background-color:#f8f8f8"span style="color:#333333"span style="color:#000000"Comparator/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/spanspan style="color:#981a1a"/span span style="color:#000000"com/span span style="color:#981a1a"=/span (span style="color:#000000"Integer/span span style="color:#000000"x/span,span style="color:#000000"Integer/span span style="color:#000000"y/span) span style="color:#981a1a"-/span { span style="color:#aa5500"//Integer 类型可以省略/span span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#aa1111""函数式接口"/span); span style="color:#770088"return/span span style="color:#000000"Integer/spanspan style="color:#116644"./spanspan style="color:#000000"compare/span(span style="color:#000000"x/span, span style="color:#000000"y/span);
};/span/span 类型推断：Lambda 表达式中的参数类型都是由编译器推断得出的（Lambda 表达式的类型依赖于上下文环境，是由编译器推断出来的）。
二、函数式接口
2.1、什么是函数式接口
（1）只包含一个抽象方法的接口，称为函数式接口。 （2）你可以通过 Lambda 表达式来创建该接口的对象。（若 Lambda 表达式抛出一个受检异常，那么该异常需要在目标接口的抽象方法上进行声明）。 （3）我们可以在任意函数式接口上使用 @FunctionalInterface 注解， 这样做可以检查它是否是一个函数式接口，同时 javadoc 也会包含一条声明，说明这个接口是一个函数式接口。 作为参数传递 Lambda 表达式：为了将 Lambda 表达式作为参数传递，接收Lambda 表达式的参数类型必须是与该 Lambda 表达式兼容的函数式接口的类型。
2.2、Java 内置四大核心函数式接口 span style="background-color:#f8f8f8"span style="color:#333333" span style="color:#000000"class/span span style="color:#000000"TestConsumer/span span style="color:#000000"implements/span span style="color:#000000"Consumer/spanspan style="color:#981a1a"/spanspan style="color:#000000"String/spanspan style="color:#981a1a"/span { span style="color:#000000"@Override/span span style="color:#000000"public/span span style="color:#000000"void/span span style="color:#000000"accept/span(span style="color:#000000"String/span span style="color:#000000"t/span) { span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#aa1111""消费型接口。。。"/span); } } span style="color:#000000"class/span span style="color:#000000"TestSupplier/span span style="color:#000000"implements/span span style="color:#000000"Supplier/spanspan style="color:#981a1a"/spanspan style="color:#000000"String/spanspan style="color:#981a1a"/span { span style="color:#000000"@Override/span span style="color:#000000"public/span span style="color:#000000"String/span span style="color:#000000"get/span() { span style="color:#770088"return/span span style="color:#221199"new/span span style="color:#000000"String/span(); } } span style="color:#000000"class/span span style="color:#000000"TestFunction/span span style="color:#000000"implements/span span style="color:#000000"Function/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/span, span style="color:#000000"String/spanspan style="color:#981a1a"/span { span style="color:#000000"@Override/span span style="color:#000000"public/span span style="color:#000000"String/span span style="color:#000000"apply/span(span style="color:#000000"Integer/span span style="color:#000000"t/span) { span style="color:#770088"return/span span style="color:#221199"new/span span style="color:#000000"String/span(); } } span style="color:#000000"class/span span style="color:#000000"TestPredicate/span span style="color:#000000"implements/span span style="color:#000000"Predicate/spanspan style="color:#981a1a"/spanspan style="color:#000000"String/spanspan style="color:#981a1a"/span { span style="color:#000000"@Override/span span style="color:#000000"public/span span style="color:#000000"boolean/span span style="color:#000000"test/span(span style="color:#000000"String/span span style="color:#000000"t/span) { span style="color:#770088"return/span span style="color:#221199"false/span; } }/span/span
（1）ConsumerT : 消费型接口 void accept(T t); 示例： span style="background-color:#f8f8f8"span style="color:#333333"span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"void/span span style="color:#000000"main/span(span style="color:#000000"String/span[] span style="color:#000000"args/span) { span style="color:#000000"happy/span(span style="color:#116644"1100/span, (span style="color:#000000"m/span) span style="color:#981a1a"-/span span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#aa1111""本次吃饭,共消费："/span span style="color:#981a1a"+/span span style="color:#000000"m/span span style="color:#981a1a"+/span span style="color:#aa1111""元"/span)); } span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"void/span span style="color:#000000"happy/span(span style="color:#000000"Integer/span span style="color:#000000"money/span, span style="color:#000000"Consumer/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/spanspan style="color:#981a1a"/span span style="color:#000000"con/span) { span style="color:#000000"con/spanspan style="color:#116644"./spanspan style="color:#000000"accept/span(span style="color:#000000"money/span);
}/span/span
（2）SupplierT : 供给型接口 T get(); 示例：
span style="background-color:#f8f8f8"span style="color:#333333"span style="color:#aa5500"//SupplierT 供给型接口 :/span span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"void/span span style="color:#000000"main/span(span style="color:#000000"String/span[] span style="color:#000000"args/span) { span style="color:#000000"List/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/spanspan style="color:#981a1a"/span span style="color:#000000"numList/span span style="color:#981a1a"=/span span style="color:#000000"getNumList/span(span style="color:#116644"5/span, () span style="color:#981a1a"-/span (span style="color:#770088"int/span) (span style="color:#000000"Math/spanspan style="color:#116644"./spanspan style="color:#000000"random/span() span style="color:#981a1a"*/span span style="color:#116644"100/span)); span style="color:#770088"for/span (span style="color:#000000"Integer/span span style="color:#000000"num/span : span style="color:#000000"numList/span) { span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#000000"num/span); } } span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"List/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/spanspan style="color:#981a1a"/span span style="color:#000000"getNumList/span(span style="color:#770088"int/span span style="color:#000000"num/span, span style="color:#000000"Supplier/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/spanspan style="color:#981a1a"/span span style="color:#000000"sup/span) { span style="color:#000000"List/spanspan style="color:#981a1a"/spanspan style="color:#000000"Integer/spanspan style="color:#981a1a"/span span style="color:#000000"list/span span style="color:#981a1a"=/span span style="color:#221199"new/span span style="color:#000000"ArrayList/spanspan style="color:#981a1a"/span(); span style="color:#770088"for/span (span style="color:#770088"int/span span style="color:#000000"i/span span style="color:#981a1a"=/span span style="color:#116644"0/span; span style="color:#000000"i/span span style="color:#981a1a"/span span style="color:#000000"num/span; span style="color:#000000"i/spanspan style="color:#981a1a"++/span) { span style="color:#000000"Integer/span span style="color:#000000"n/span span style="color:#981a1a"=/span span style="color:#000000"sup/spanspan style="color:#116644"./spanspan style="color:#000000"get/span(); span style="color:#000000"list/spanspan style="color:#116644"./spanspan style="color:#000000"add/span(span style="color:#000000"n/span); } span style="color:#770088"return/span span style="color:#000000"list/span;
} /span/span
(3) FunctionT, R : 函数型接口 R apply(T t); 示例：
span style="background-color:#f8f8f8"span style="color:#333333"span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"void/span span style="color:#000000"main/span(span style="color:#000000"String/span[] span style="color:#000000"args/span) { span style="color:#000000"String/span span style="color:#000000"newStr/span span style="color:#981a1a"=/span span style="color:#000000"strHandler/span(span style="color:#aa1111""\t\t\t 五一四天乐 "/span, (span style="color:#000000"str/span) span style="color:#981a1a"-/span span style="color:#000000"str/spanspan style="color:#116644"./spanspan style="color:#000000"trim/span()); span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#000000"newStr/span); span style="color:#000000"String/span span style="color:#000000"subStr/span span style="color:#981a1a"=/span span style="color:#000000"strHandler/span(span style="color:#aa1111""我一定要做数据挖掘"/span, (span style="color:#000000"str/span) span style="color:#981a1a"-/span span style="color:#000000"str/spanspan style="color:#116644"./spanspan style="color:#000000"substring/span(span style="color:#116644"2/span, span style="color:#116644"5/span)); span style="color:#000000"System/spanspan style="color:#116644"./spanspan style="color:#000000"out/spanspan style="color:#116644"./spanspan style="color:#221199"println/span(span style="color:#000000"subStr/span);
}
span style="color:#aa5500"// 需求：用于处理字符串/span
span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"String/span span style="color:#000000"strHandler/span(span style="color:#000000"String/span span style="color:#000000"str/span, span style="color:#000000"Function/spanspan style="color:#981a1a"/spanspan style="color:#000000"String/span, span style="color:#000000"String/spanspan style="color:#981a1a"/span span style="color:#000000"fun/span) { span style="color:#770088"return/span span style="color:#000000"fun/spanspan style="color:#116644"./spanspan style="color:#000000"apply/span(span style="color:#000000"str/span);
}/span/span
(4) PredicateT : 断言型接口 boolean test(T t); 示例：
span style="background-color:#f8f8f8"span style="color:#333333"span style="color:#000000"public/span span style="color:#000000"static/span span style="color:#000000"void/span span style="color:#000000"main/span(span style="color:#000000"String/span[] span style="color:#000000"args/span) { span style="color:#000000"List/spanspan style="color:#981a1a"/spanspan style="color:#000000"String/spanspan style="color:#981a1a"/span span style="color:#000000"list/span span style="color:#981a1a"=/span span style="color:#000000"Arrays/spanspan style="color:#116644"./spanspan style="color:#000000"asList/span(span style="color:#aa1111""Hello"/span, span style="color:#aa1111""WWW"/span, span style="color:#aa1111""Lambda"/span, span style="color:#aa1111""!!"/span, span style="color:#aa1111""ok"/span); span style="color:#000000"List/spanspan style="color:#981a1a"/spanspan style="color:#000000"String/spanspan style="color:#981a1a"/span span style="color:#000000"strList/span span style="color:#981a1a"=/span span style="color:#000000"filterStr/span(span style="color:#000000"list/span, (span style="color:#
