本文共 4959 字，大约阅读时间需要 16 分钟。

Lambda表达式、

Main.java

package Lambda表达式;public class Main {
       public  String message="你好";    public static void main(String[]argv){
           /*        功能性接口:只有一个抽象方法        */        greet(new ConsolePrinter());        //使用匿名类        greet(new Printer() {
               @Override            public void print(String message) {
                   System.out.println("使用匿名类"+message);            }        });        //lambda表达式        greet((String message) -> {
               System.out.println("Lambda表达式"+message);        });        //定义lambda表达式        Printer lambdaPrinter=message -> {
   System.out.println(message);};        lambdaPrinter.print("helloworld");        //lambda执行体中的this为当前所执行lambda表达式的对象实体        //使用方法引用        greet(message -> System.out.println(message));        greet(System.out::println);        //自定义        greet(message -> print(message));        greet(Main::print);        //静态方法        //gree(类名::方法名)        //实体方法        //gree(对象变量名::方法名)    }    public static void greet(Printer printer){
           printer.print("Hello world");    }    public static void print(String message){
           System.out.println("方法引用"+message);    }}

Printer.java

package Lambda表达式;public interface Printer {
       void print(String message);}

ConsolePrinter.java

package Lambda表达式;public class ConsolePrinter implements Printer{
       @Override    public void print(String message) {
           System.out.println(message);    }}

Consumer接口

package Lambda表达式.Consumer接口;import java.util.List;import java.util.function.Consumer;public class Main {
       public static int sum=0;    public static void main(String[]argv){
           List
   
    list= List.of(3,4,5,6);        //遍历        for(Integer num:list){
               System.out.println(num);        }        //使用Consumer接口        list.forEach((Integer item)->{
               sum+=item;            System.out.println(item);        });        System.out.println("sum="+sum);        //定义Consumer接口:只接受参数没有返回值        Consumer
    
      print=(Integer item)->System.out.println("print"+item);        list.forEach(print);        /*消费者链*/        Consumer
     
       print1=item->System.out.println("print1+"+item);        list.forEach(print.andThen(print1));//        print3//        print1+3//        print4//        print1+4//        print5//        print1+5//        print6//        print1+6    }}
     
    
   

Function接口

package Lambda表达式.Function接口;import java.util.function.Function;public class Main {
       public static void main(String[]argv){
           Function
   
     map=(String str)->{
   return str.length();};        var num=map.apply("hello");        System.out.println(num);        /*有趣的实例*/        Function
    
     replaceColon=str->str.replace(":","=");        Function
     
      addBraces=str->"{"+str+"}";        var result=replaceColon.                            andThen(addBraces)                            .apply("key:value");        System.out.println(result);//{key=value}        //以相反的顺序组合函数        System.out.println(addBraces.compose(replaceColon).apply("key:value"));    }}
     
    
   

BinaryOperator接口

package Lambda表达式.BinaryOperator接口;import java.util.function.BinaryOperator;import java.util.function.Function;public class Main {
       public static void main(String[]argv){
           BinaryOperator
   
    add=(a,b)->a+b;        Function
    
      square= a->a*a;        System.out.println(add.andThen(square).apply(1,2));        //(1+2)^2    }}
    
   

Predicate接口

package Lambda表达式.Predicate接口;import java.util.function.Predicate;public class Main {
       public static void main(String[]argv){
           Predicate
   
    isLongerThan5=str->str.length()>5;        System.out.println(isLongerThan5.test("hcv"));//false        //组合谓词接口        Predicate
    
     hasLeftBrace=str->str.startsWith("{");        Predicate
     
      hasRightBrace=str->str.endsWith("}");        //and        Predicate
      
       hasLeftRightBrace=hasLeftBrace.and(hasRightBrace);        System.out.println(hasLeftRightBrace.test("{hello}"));//true        //or        Predicate
       
        hasLeftOrRightBrace=hasLeftBrace.or(hasRightBrace);        System.out.println(hasLeftOrRightBrace.test("hello}"));//true        //取反        hasLeftBrace.negate();    }}
       
      
     
    
   

Supplier接口

package Lambda表达式.Supplier接口;import java.util.function.Supplier;public class Main {
       public static void main(String[]argv){
           Supplier
   
     getRandom=()->{
   return Math.random();};        var random=getRandom.get();        System.out.println(random);    }}
   

UnaryOperator接口

package Lambda表达式.UnaryOperator接口;import java.util.function.UnaryOperator;public class Main {
       public static void main(String[]argv){
           UnaryOperator
   
     square=n->n*n;        UnaryOperator
    
      increment=n->n+1;        var result=increment.andThen(square).apply(1);        System.out.println(result);//4        //(1+1)*(1+1)=4    }}
    
   

转载地址：http://rucki.baihongyu.com/