Java8 Stream 基本操作示例

来源：互联网发布：南风知我意2生子番外编辑：程序博客网时间：2024/04/27 10:50
package Stream;import java.util.ArrayList;import java.util.Arrays;import java.util.IntSummaryStatistics;import java.util.List;import java.util.Optional;import java.util.OptionalInt;import java.util.stream.Collectors;public class Java8Stream {    public static void main(String[] args) {        System.out.println("hello Stream");        List<Person> list=getPersoms();        //调用Stream(流)API函数        //List<Person> studentList        boolean isAllMatch=list.stream().allMatch(Person::isStudent);        boolean isAnyMatch=list.stream().anyMatch(Person::isStudent);        boolean isALLNotMatch=list.stream().noneMatch(Person::isStudent);        System.out.println("is All student? "+isAllMatch);        System.out.println("is Any student? "+isAnyMatch);        System.out.println("is no student? "+isALLNotMatch);        List<String> studentList=list.stream().                filter(Person::isStudent).//筛选出学生                //map((Person person)->person.getName()).//获取学生名字形成新的流                map(Person::getName).                collect(Collectors.toList());//将新的流返回给studentList        System.out.println("studentList: "+studentList);        //flatMap        List<String> strlist=new ArrayList<String>();        strlist.add("I am a boy");        strlist.add("I love the girl");        strlist.add("But the girl loves another girl");        List<String> resultlist=strlist.stream().                map(line->line.split(" ")).//转化为String[]                flatMap(Arrays::stream).//转化为Stream                distinct().//去除重复的String                collect(Collectors.toList());//返回集合        System.out.println("resultlist: "+resultlist);        //获取第一个元素findFirst        Optional<Person> person = list.stream().findFirst();        System.out.println("findFirst: "+person.get());        OptionalInt maxAge  =list.stream().mapToInt(Person::getAge).max();        System.out.println("maxAge: "+maxAge.getAsInt());        IntSummaryStatistics all=list.stream().collect(Collectors.summarizingInt(Person::getAge));        System.out.println("sumAge:"+all.getSum()+"   aver"+all.getAverage()                            +"   minAge"+all.getMin()+"   maxAge"+all.getMax());    }    /**     * 测试数据      * @return     */    public static List<Person> getPersoms(){        List<Person> list=new ArrayList<Person>();        Person person;        for(int i=0;i<10;i++){            person=new Person();            person.setAge(i);            person.setName("lice"+String.valueOf(i));            person.setStudent(true);            list.add(person);        }        return list;    }    /**     * 测试数据      * @return     */    public static List<Integer> getNumbers(){        List<Integer> list=new ArrayList<Integer>();        for(int i=0;i<10;i++)            list.add(i);        return list;    }}
阅读全文
0 0