Java——Stream流（1/2）：Stream流入门、Stream流的创建（认识Stream、体验Stream流、Stream流的使用步骤、获取Stream流的方法）

List<String> list = new ArrayList<>();
list.add("张无忌");
list.add("周芷若");
list.add("赵敏");
list.add("张强");
list.add("张三丰");

public class streamTest1 {
    public static void main(String[] args) {
        List<String> names = new ArrayList<>();
        Collections.addAll(names,"张三丰","张无忌","周芷若","赵敏","张强");
        System.out.println(names);
        System.out.println("------------------");
        //找出姓张、且是3个字的名字，存入到一个新集合中去
        List<String> list = new ArrayList<>();
        for(String name:names){
            if(name.startsWith("张") && name.length() == 3){
                list.add(name);
            }
        }
        System.out.println(list);
    }
}

package Stream;
 
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
 
public class streamTest1 {
    public static void main(String[] args) {
        List<String> names = new ArrayList<>();
        Collections.addAll(names,"张三丰","张无忌","周芷若","赵敏","张强");
        System.out.println(names);
        System.out.println("------------------");
 
        //找出姓张、且是3个字的名字，存入到一个新集合中去
        
        //开始使用Stream流来解决这个问题
        List<String> list2 = names.stream().filter(s -> s.startsWith("张"))
                .filter(a -> a.length()==3).collect(Collectors.toList());
        System.out.println(list2);
    }
}

import java.util.*;
import java.util.stream.Stream;
 
public class streamTest2 {
    public static void main(String[] args) {
        //2.获取Set集合的Stream流
        Set<String> set = new HashSet<>();
        Collections.addAll(set,"刘德华","张曼玉","蜘蛛精","马德","德玛西亚");
        Stream<String> stream1 = set.stream();
        //顺带遍历出名字带“德”的
        stream1.filter(s -> s.contains("德")).forEach(s -> System.out.println(s));
    }
}
 

import java.util.*;
import java.util.stream.Stream;
 
public class streamTest2 {
    public static void main(String[] args) {
        //3.获取Map集合的Stream流
        Map<String,Double> map = new HashMap<>();
        map.put("古力娜扎",172.3);
        map.put("迪丽热巴",168.3);
        map.put("马尔扎哈",166.3);
        map.put("卡尔扎巴",168.3);
 
        //键
        Set<String> keys = map.keySet();
        Stream<String> ks = keys.stream();
 
        //值
        Collection<Double> values = map.values();
        Stream<Double> vs = values.stream();
 
        //键+值
        Set<Map.Entry<String,Double>> entries = map.entrySet();
        Stream<Map.Entry<String,Double>> kvs = entries.stream();
 
        //遍历出键中包含“巴”字的元素
        kvs.filter(e -> e.getKey().contains("巴"))
                .forEach(e -> System.out.println(e.getKey() + "-->" + e.getValue()));
    }
}