From ea26f20f5c251a1be7fcd0e5911a84446991b874 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=88=98=E9=92=8A?= <zhao.liu@guanaitong.com>
Date: Thu, 2 Jan 2020 17:35:50 +0800
Subject: [PATCH] =?UTF-8?q?map-reduce=20=E5=BD=92=E7=BA=A6?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../streamapi/StreamAPIEndTest.java           | 14 ++++-
 .../java8learn/streamapi/StreamApiTest2.java  |  3 ++
 .../streamapi/StreamReduceTest.java           | 54 +++++++++++++++++++
 3 files changed, 69 insertions(+), 2 deletions(-)
 create mode 100644 src/test/java/com/wind/java8learn/streamapi/StreamReduceTest.java

diff --git a/src/test/java/com/wind/java8learn/streamapi/StreamAPIEndTest.java b/src/test/java/com/wind/java8learn/streamapi/StreamAPIEndTest.java
index 722501f..7e50c39 100644
--- a/src/test/java/com/wind/java8learn/streamapi/StreamAPIEndTest.java
+++ b/src/test/java/com/wind/java8learn/streamapi/StreamAPIEndTest.java
@@ -1,6 +1,7 @@
 package com.wind.java8learn.streamapi;
 
 import com.wind.java8learn.model.Employee;
+import lombok.NonNull;
 import org.junit.jupiter.api.Test;
 
 import java.util.Arrays;
@@ -84,12 +85,21 @@ public class StreamAPIEndTest {
 
         Optional<Employee> maxEE = employeeList.stream()
                 .max((e1, e2) -> Double.compare(e1.getSalary(),e2.getSalary()));
-        System.out.println("薪资最高的：" + maxEE.get());
+        System.out.println("薪资最高的雇员信息：" + maxEE.get());
 
         Optional<Employee> minEE = employeeList.stream()
                 .min((e1, e2) -> Double.compare(e1.getSalary(),e2.getSalary()));
-        System.out.println("薪资最低的：" + minEE.get());
+        System.out.println("薪资最低的雇员信息：" + minEE.get());
 
+        Optional<Double> maxDouble = employeeList.stream()
+                .map(Employee::getSalary)
+                .max(Double::compare);
+        System.out.println("最高年薪值是："+maxDouble.get());
+
+        Optional<Double> minDouble = employeeList.stream()
+                .map(Employee::getSalary)
+                .min(Double::compare);
+        System.out.println("最低年薪值是："+minDouble.get());
 
     }
 
diff --git a/src/test/java/com/wind/java8learn/streamapi/StreamApiTest2.java b/src/test/java/com/wind/java8learn/streamapi/StreamApiTest2.java
index cacb400..0e56d3b 100644
--- a/src/test/java/com/wind/java8learn/streamapi/StreamApiTest2.java
+++ b/src/test/java/com/wind/java8learn/streamapi/StreamApiTest2.java
@@ -104,6 +104,9 @@ public class StreamApiTest2 {
                 .skip(2) //跳过 满足条件的前 2 条数据
                 .distinct() //重写hashCode() 和 equals()方法后，distinct()才会生效
                 .forEach(System.out::println);
+
+
+
     }
 
 
diff --git a/src/test/java/com/wind/java8learn/streamapi/StreamReduceTest.java b/src/test/java/com/wind/java8learn/streamapi/StreamReduceTest.java
new file mode 100644
index 0000000..0303c12
--- /dev/null
+++ b/src/test/java/com/wind/java8learn/streamapi/StreamReduceTest.java
@@ -0,0 +1,54 @@
+package com.wind.java8learn.streamapi;
+
+import com.wind.java8learn.model.Employee;
+import lombok.NonNull;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * @Author :wind
+ * @Description : stream api 归约
+ *                即 可以将流中的元素反复结合起来，得到一个值
+ * @Date : 2020/1/2 17:15
+ */
+public class StreamReduceTest {
+
+    List<Employee> employeeList = Arrays.asList(
+            new Employee("张三", 29, 19800.00, Employee.Status.FREE),
+            new Employee("李四", 19, 8800.00, Employee.Status.BUSY),
+            new Employee("王五", 21, 10800.00,Employee.Status.BUSY),
+            new Employee("麻子", 25, 13900.00,Employee.Status.FREE),
+            new Employee("大佬", 24, 10600.00,Employee.Status.BUSY),
+            new Employee("麻子2", 26, 10900.00,Employee.Status.FREE),
+            new Employee("麻子3", 27, 10900.00,Employee.Status.FREE)
+    );
+
+    @Test
+    public void test(){
+        List<Integer> integerList  = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+        Integer sum = integerList.stream()
+                .reduce(0, (x, y) -> x + y);//跌加的初始值是 0
+        System.out.println("reduce的结果是 ："+sum);
+
+        System.out.println("===================================");
+
+        //求雇员工资的和 （两种reduce方法）
+        //方式一
+        Double reduceSum = employeeList.stream()
+                .map(Employee::getSalary) //提取工资
+                .reduce(0.00, (x, y) -> (x + y));//迭加的初始工资是 0.00
+        System.out.println("雇员的工资总和："+reduceSum);
+
+        //方式一 (返回的是 Optional )
+        Optional<Double> op = employeeList.stream()
+                .map(Employee::getSalary) //提取工资
+                .reduce(Double::sum);
+        System.out.println("雇员的工资总和："+op.get());
+
+
+
+    }
+}
-- 
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