JDK8對List的簡化操作-Lambda運算式

import java.util.*;import java.util.stream.Collectors;public class Test {public static void main(String[] args) {List<Student> list = new ArrayList<>();Student student1 = new Student();student1.setAge("12");student1.setSex(0);Student student2 = new Student();student2.setAge("13");student2.setSex(2);Student student3 = new Student();student3.setAge("11");student3.setSex(1);Student student4 = new Student();student4.setAge("18");student4.setSex(1);Student student5 = new Student();student5.setAge("18");student5.setSex(0);Student student6 = new Student();student6.setAge("18");student6.setSex(2);Student student7 = new Student();student7.setAge("18");student7.setSex(2);list.add(student1);list.add(student2);list.add(student3);list.add(student4);list.add(student5);list.add(student6);list.add(student7);List<Demo> demos = new ArrayList<Demo>();// 未經處理資料System.out.println("未經處理資料 組裝list<demo>*******************");demos = list.stream().map(student -> new Demo(student.getAge(), student.getSex())).collect(Collectors.toList());demos.forEach(demo -> {System.out.println("年齡 " + demo.getAge() + "  性別 " + demo.getSex() + ",");});// 只取sex為0System.out.println("只取sex為0****************");List<Demo> demorm = demos.stream().filter(demo -> demo.getSex() == 0).distinct().collect(Collectors.toList());demorm.forEach(demo -> {System.out.println("年齡 " + demo.getAge() + "  性別 " + demo.getSex() + ",");});// 篩選年齡大於12歲System.out.println("篩選年齡大於12歲的*************");List<Demo> demoFilter = demos.stream().filter(demo -> Integer.valueOf(demo.getAge()) > 12).collect(Collectors.toList());demoFilter.forEach(demo -> {System.out.println("年齡 " + demo.getAge() + "  性別 " + demo.getSex() + ",");});// 排序System.out.println("排序******************");List<Demo> demoSort = demos.stream().sorted((s1, s2) -> s1.getAge().compareTo(s2.getAge())).collect(Collectors.toList());demoSort.forEach(demo -> {System.out.println("年齡 " + demo.getAge() + "  性別 " + demo.getSex() + ",");});// 倒序System.out.println("倒序****************");ArrayList<Demo> demoArray = (ArrayList<Demo>) demos;Comparator<Demo> comparator = (h1, h2) -> h1.getAge().compareTo(h2.getAge());demos.sort(comparator.reversed());//ordemos.sort(Comparator.comparing(Demo::getAge).reversed());demos.forEach(demo -> {System.out.println("年齡 " + demo.getAge() + "  性別 " + demo.getSex() + ",");});// 多條件正序System.out.println("多條件排序正序****************");demoArray.sort(Comparator.comparing(Demo::getSex).thenComparing(Demo::getAge));demoArray.forEach(demo -> {System.out.println("年齡 " + demo.getAge() + "  性別 " + demo.getSex() + ",");});// 多條件倒序System.out.println("多條件排序倒序 sex  倒序****************");demoArray.sort(Comparator.comparing(Demo::getSex).reversed().thenComparing(Demo::getAge));demoArray.forEach(demo -> {System.out.println("年齡 " + demo.getAge() + "  性別 " + demo.getSex() + ",");});// 按照年齡分組System.out.println("根據age分組結果為Map****************");Map<String, List<Demo>> demoOder = demos.stream().collect(Collectors.groupingBy(Demo::getAge));System.out.println(demoOder);}}class Demo {private String name;private Integer sex;private String age;public Demo(String age, Integer sex) {this.age = age;this.sex = sex;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getSex() {return sex;}public void setSex(Integer sex) {this.sex = sex;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}}class Student {private String age;private Integer sex;public String getAge() {return age;}public void setAge(String age) {this.age = age;}public Integer getSex() {return sex;}public void setSex(Integer sex) {this.sex = sex;}}