源码

package com.keyba.example;import java.util.*;import java.util.function.Consumer;import java.util.function.Predicate;import java.util.stream.Collectors;public class LambdaTest {    public static void main(String[] args) {        String[] atp = {"Rafael Nadal", "Novak Djokovic", "Stanislas Wawrinka", "David Ferrer",                "Roger Federer", "Andy Murray", "Tomas Berdych", "Juan Martin Del Potro"};        List
    
      players = Arrays.asList(atp);        // 以前的循环方式        for (String player : players) {            System.out.print(player + "; ");        }        System.out.println();        // 使用 lambda 表达式以及函数操作(functional operation)        players.forEach((player) -> System.out.print(player + "; "));        System.out.println();        // 在 Java 8 中使用双冒号操作符(double colon operator)        players.forEach(System.out::println);    }}class AcceptMethod {    public static void printValue(String str) {        System.out.println("print value : " + str);    }}class MyTest {    public static void main(String[] args) {        List
     
       al = Arrays.asList("a", "b", "c", "d");        al.forEach(AcceptMethod::printValue);        //下面的方法和上面等价的        Consumer
      
        methodParam = AcceptMethod::printValue; //方法参数        al.forEach(x -> methodParam.accept(x));//方法执行accept    }}class Employee {    private String firstName, lastName, job, gender;    private int salary, age;    public Employee(String firstName, String lastName, String job,                    String gender, int age, int salary) {        this.firstName = firstName;        this.lastName = lastName;        this.gender = gender;        this.age = age;        this.job = job;        this.salary = salary;    }    public String getFirstName() {        return firstName;    }    public String getLastName() {        return lastName;    }    public String getJob() {        return job;    }    public String getGender() {        return gender;    }    public void setSalary(int salary) {        this.salary = salary;    }    public int getSalary() {        return salary;    }    public int getAge() {        return age;    }    public static void main(String[] args) {        List
       
         javaProgrammers = new ArrayList
        
         () {            {                add(new Employee("Elsdon", "Jaycob", "Java programmer", "male", 43, 2000));                add(new Employee("Tamsen", "Brittany", "Java programmer", "female", 23, 1500));                add(new Employee("Floyd", "Donny", "Java programmer", "male", 33, 1800));                add(new Employee("Sindy", "Jonie", "Java programmer", "female", 32, 1600));                add(new Employee("Vere", "Hervey", "Java programmer", "male", 22, 1200));                add(new Employee("Maude", "Jaimie", "Java programmer", "female", 27, 1900));                add(new Employee("Shawn", "Randall", "Java programmer", "male", 30, 2300));                add(new Employee("Jayden", "Corrina", "Java programmer", "female", 35, 1700));                add(new Employee("Palmer", "Dene", "Java programmer", "male", 33, 2000));                add(new Employee("Addison", "Pam", "Java programmer", "female", 34, 1300));            }        };        System.out.println("所有程序员的姓名:");        javaProgrammers.forEach((p) -> System.out.printf("%s %s; ", p.getFirstName(), p.getLastName()));        System.out.println();        System.out.println("给程序员加薪 5% :");        javaProgrammers.forEach(p -> System.out.printf(String.valueOf(p.getSalary()) + "; "));        Consumer
         
           giveRaise = e -> e.setSalary(e.getSalary() / 100 * 5 + e.getSalary()); javaProgrammers.forEach(giveRaise); System.out.println(); javaProgrammers.forEach(p -> System.out.printf(String.valueOf(p.getSalary()) + "; ")); System.out.println(); System.out.println("下面是月薪超过 $1,400 的JAVA程序员:"); javaProgrammers.stream() .filter((p) -> (p.getSalary() > 1400)) .forEach((p) -> System.out.printf("%s %s %s; ", p.getFirstName(), p.getLastName(), p.getSalary())); System.out.println(); // 定义 filters Predicate
          
            ageFilter = (p) -> (p.getAge() > 25); Predicate
           
             salaryFilter = (p) -> (p.getSalary() > 1400); Predicate
            
              genderFilter = (p) -> ("female".equals(p.getGender())); System.out.println("年龄大于 24岁的女性 Java programmers:"); javaProgrammers.stream() .filter(ageFilter) .filter(salaryFilter) .filter(genderFilter) .forEach((p) -> System.out.printf("%s %s; ", p.getFirstName(), p.getLastName())); System.out.println(); System.out.println("根据 salary 排序 Java programmers:"); List
             
               sortedJavaProgrammers = javaProgrammers .stream() .sorted((p, p2) -> (p.getSalary() - p2.getSalary())) .limit(3) .collect(Collectors.toList()); sortedJavaProgrammers.forEach((p) -> System.out.printf("%s %s;%s %n", p.getFirstName(), p.getLastName(), p.getSalary())); System.out.println("将 Java programmers 的 first name 拼接成字符串:"); String javaDevelopers = javaProgrammers .stream() .map(Employee::getFirstName) .collect(Collectors.joining(" ; ")); // 在进一步的操作中可以作为标记(token) System.out.println(javaDevelopers); System.out.println("将 Java programmers 的 first name 存放到 Set:"); Set
              
                javaDevFirstName = javaProgrammers .stream() .map(Employee::getFirstName) .collect(Collectors.toSet()); System.out.println(javaDevFirstName); System.out.println("将 Java programmers 的 first name 存放到 TreeSet:"); TreeSet
               
                 javaDevLastName = javaProgrammers .stream() .map(Employee::getLastName) .collect(Collectors.toCollection(TreeSet::new)); System.out.println(javaDevLastName); System.out.println("计算付给 Java programmers 的所有money:"); int totalSalary = javaProgrammers .parallelStream() .mapToInt(p -> p.getSalary()) .sum(); System.out.println(totalSalary); //计算 count, min, max, sum, and average for numbers List
                
                  numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); IntSummaryStatistics stats = numbers .stream() .mapToInt((x) -> x) .summaryStatistics(); System.out.println("List中最大的数字 : " + stats.getMax()); System.out.println("List中最小的数字 : " + stats.getMin()); System.out.println("所有数字的总和 : " + stats.getSum()); System.out.println("所有数字的平均值 : " + stats.getAverage()); }}
                
               
              
             
            
           
          
         
        
       
      
     
    

结果

所有程序员的姓名:Elsdon Jaycob; Tamsen Brittany; Floyd Donny; Sindy Jonie; Vere Hervey; Maude Jaimie; Shawn Randall; Jayden Corrina; Palmer Dene; Addison Pam; 给程序员加薪 5% :2000; 1500; 1800; 1600; 1200; 1900; 2300; 1700; 2000; 1300; 2100; 1575; 1890; 1680; 1260; 1995; 2415; 1785; 2100; 1365; 下面是月薪超过 $1,400 的JAVA程序员:Elsdon Jaycob 2100; Tamsen Brittany 1575; Floyd Donny 1890; Sindy Jonie 1680; Maude Jaimie 1995; Shawn Randall 2415; Jayden Corrina 1785; Palmer Dene 2100; 年龄大于 24岁的女性 Java programmers:Sindy Jonie; Maude Jaimie; Jayden Corrina; 根据 salary 排序 Java programmers:Vere Hervey;1260 Addison Pam;1365 Tamsen Brittany;1575 将 Java programmers 的 first name 拼接成字符串:Elsdon ; Tamsen ; Floyd ; Sindy ; Vere ; Maude ; Shawn ; Jayden ; Palmer ; Addison将 Java programmers 的 first name 存放到 Set:[Elsdon, Shawn, Palmer, Addison, Maude, Floyd, Vere, Tamsen, Jayden, Sindy]将 Java programmers 的 first name 存放到 TreeSet:[Brittany, Corrina, Dene, Donny, Hervey, Jaimie, Jaycob, Jonie, Pam, Randall]计算付给 Java programmers 的所有money:18165List中最大的数字 : 10List中最小的数字 : 1所有数字的总和   : 55所有数字的平均值 : 5.5