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+# **Stream流介绍：**
+
+**配合lambda表达式，简化集合和数组操作**
+
+## **获取Stream流对象**
+
+![image-20251221181445689](https://gitee.com/icecat2233/picture/raw/master/20251221181446881.png)
+
+## **Stream流中间操作方法：**
+
+![image-20251221182850306](https://gitee.com/icecat2233/picture/raw/master/20251221182851889.png)
+
+## 获取对象流演示：
+
+![image-20251221194116622](https://gitee.com/icecat2233/picture/raw/master/20251221194131811.png)
+
+### **示例：**
+
+```Java
+ArrayList<String> list = new ArrayList<>();
+        list.add("杏菜");
+        list.add("佳树");
+        list.add("小鞠");
+        list.add("梦子");
+        //集合Stream流对象
+        list.stream().filter(s -> s.startsWith("杏")).forEach(s -> System.out.println(s));
+        //数组流对象
+        int[] arr = {1, 2, 3};
+        Arrays.stream(arr).forEach(s-> System.out.println(s));
+        HashSet<Integer> hs = new HashSet<>();
+        hs.add(1);
+        hs.add(4);
+        hs.add(3);
+        hs.add(5);
+        //map集合流对象，需要间接获取 - map.entrySet().stream
+        HashMap<String,Integer> hm = new HashMap<>();
+        hm.put("张",13);
+        hm.put("李",14);
+        hm.put("王",15);
+        Set<Map.Entry<String, Integer>> entries = hm.entrySet();
+        entries.stream()
+                .filter(entry -> !entry.getKey().startsWith("张"))
+                .forEach(entry -> System.out.println(entry.getKey()+"---"+entry.getValue()));
+        //零散数据获取Stream流对象
+        Stream.of("1","e",3).forEach(s-> System.out.println(s));
+```
+
+## 中间操作方法
+
+![image-20251221200537334](https://gitee.com/icecat2233/picture/raw/master/20251221200538411.png)
+
+示例：
+
+```java
+ArrayList<Integer> list = new ArrayList<>();
+        Stream<Integer> s2 = list.stream();
+        ArrayList<Integer> list1= new ArrayList<>();
+        Stream<Integer> s1 = list1.stream();
+        Collections.addAll(list1,5,6,7);
+        Collections.addAll(list,1,2,3,4);
+        //filter过滤方法
+        list.stream().filter(s -> s!=2).forEach(s-> System.out.print(s));
+        System.out.println('\n');
+        //limit获取前几个元素
+        list.stream().limit(2).forEach(integer -> System.out.print(integer));
+        System.out.println('\n');
+        //skip跳过几个元素
+        System.out.println("跳过之后的元素");
+        list.stream().skip(1).forEach(s-> System.out.print(s));
+        System.out.println('\n');
+        //concat(Stream a,Stream b)合并ab为一个流
+        Stream<Integer> s3 = Stream.concat(s1, s2);
+        s3.forEach(new Consumer<Integer>() {
+            @Override
+            public void accept(Integer s) {
+                System.out.println(s);
+            }
+        });
+        //distinct方法去除流中重复的元素依赖(hashCode 和 equals方法)
+        //在此会报错，因为上面已经消费过了不能重新使用
+        list.stream().distinct().forEach(s-> System.out.println(s));
+```
+
+![image-20251221203020331](https://gitee.com/icecat2233/picture/raw/master/20251221203021575.png)
+
+**注意：若流已经被使用过，或已使用终结方法，就不允许再次使用**
+
+## 终结方法
+
+![image-20251221203822185](https://gitee.com/icecat2233/picture/raw/master/20251221203823266.png)
+
+**示例：**
+
+```java
+//count方法，返回元素个数
+Stream<Integer> s1 = Stream.of(2, 3, 4, 5, 6, 7, 8).filter(integer -> integer % 2 == 0);
+long count = s1.count();
+System.out.println(count);
+```
+
+## 重点：收集操作
+
+为何：因为Stream流操作是不会修改数据源的，图为示例：
+
+![image-20251221203945267](https://gitee.com/icecat2233/picture/raw/master/20251221203946590.png)
+
+### **如何收集：**
+
+![image-20251221205629800](https://gitee.com/icecat2233/picture/raw/master/20251221205631348.png)
+
+**示例：**
+
+```java
+//Stream流收集操作
+Stream<Integer> s1 = Stream.of(1, 2, 3, 4, 5, 6, 7);
+List list1 = s1.limit(3).collect(Collectors.toList());//JDK17版本之后可以将Collectors去除
+System.out.println(list1);
+```
+
+### **转为map操作（较为复杂）**
+
+**重点示例**
+
+```java
+//    将ArrayList中年龄大于15的收集到一个新的map集合中去
+    public static void main(String[] args) {
+        //将Stream流收集到map所需操作
+        ArrayList<String> list = new ArrayList<>();
+        Collections.addAll(list,"杏菜,15","佳树,16","老马,17");
+        Map<String, Integer> map = list.stream().filter(new Predicate<String>() {
+            @Override
+            public boolean test(String s) {
+                //过滤操作，将字符串数据从逗号切割装入数组，0号索引为名字，1号为年龄
+                String[] split = s.split(",");
+                //将字符串转为int类型并比较年龄，返回大于等于16岁的
+                int age = Integer.parseInt(split[1]);
+                return age >= 16;
+            }
+        }).collect(Collectors.toMap(new Function<String, String>() {
+            //创建map集合，第一个匿名内部类为装入键值
+            @Override
+            public String apply(String s) {
+                return s.split(",")[0];
+            }
+        }, new Function<String, Integer>() {
+            //第二个为装入年龄值，并将类型从String改为int
+            @Override
+            public Integer apply(String s) {
+                return Integer.parseInt(s.split(",")[1]);
+            }
+        }));
+        System.out.println(map);
+```
+
+# Stream流综合案例
+
+```java
+package com.icacat.day12;
+
+import java.util.ArrayList;
+import java.util.function.Consumer;
+import java.util.function.Predicate;
+import java.util.stream.Stream;
+
+public class StreamDemo6 {
+    public static void main(String[] args) {
+        ArrayList<String> manList = new ArrayList<>();
+        manList.add("温水和彦");
+        manList.add("社长");
+        manList.add("桐谷和人");
+        manList.add("勇太");
+        ArrayList<String> womanList = new ArrayList<>();
+        womanList.add("杏菜");
+        womanList.add("小鞠");
+        womanList.add("佳树");
+        womanList.add("千早");
+
+        Stream<String> s1 = manList.stream().filter(new Predicate<String>() {
+            @Override
+            public boolean test(String s) {
+                return s.length() == 4;
+            }
+        }).limit(2);
+        Stream<String> s2 = womanList.stream().skip(1).filter(s -> s.startsWith("佳"));
+        Stream<String> total = Stream.concat(s1, s2);
+        total.forEach(new Consumer<String>() {
+            @Override
+            public void accept(String name) {
+                Actor ac = new Actor(name);
+                System.out.println(ac);
+            }
+        });
+    }
+}
+
+class Actor{
+    private String name;
+
+    public Actor() {
+    }
+
+    public Actor(String name) {
+        this.name = name;
+    }
+
+    /**
+     * 获取
+     * @return name
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * 设置
+     * @param name
+     */
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String toString() {
+        return "Actor{name = " + name + "}";
+    }
+}
+```