docs: [Java 8 Lambda 和 Comparator 排序](/java8/comparator/)

niumoo · niumoo · commit 784ec5d9e95b · 2022-04-06T19:45:23.000+08:00
diff --git a/core-java-modules/core-java-8/README.md b/core-java-modules/core-java-8/README.md
@@ -2,6 +2,7 @@
 当前模块包含 Java 8 新特性相关代码
 
 ### 相关文章
+- [Java 8 Lambda 和 Comparator 排序](/java8/comparator/)
 - [Java 8 函数接口 UnaryOperator ](https://www.wdbyte.com/java8/java8-unaryoperaotr)
 - [Java 8 函数接口 BiPredicate ](https://www.wdbyte.com/java8/java8-bipredicate)
 - [Java 8 函数接口 BiFunction ](https://www.wdbyte.com/java8/java8-bifunction/)
diff --git a/core-java-modules/core-java-8/pom.xml b/core-java-modules/core-java-8/pom.xml
@@ -18,4 +18,28 @@
         <maven.compiler.target>1.8</maven.compiler.target>
     </properties>
 
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.junit</groupId>
+                <artifactId>junit-bom</artifactId>
+                <version>5.8.2</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.22</version>
+        </dependency>
+    </dependencies>
+
 </project>
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Function.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Function.java
@@ -4,7 +4,6 @@
 import java.util.List;
 import java.util.function.Predicate;
 
-import org.junit.Test;
 
 /**
  * <p>
@@ -20,7 +19,6 @@
  */
 public class Jdk8Function {
 
-    @Test
     public void testFunction() {
         // 构造器引用
         final Car bmwCar = Car.create(Car::new);
@@ -39,7 +37,6 @@ public void testFunction() {
     /**
      * 函数接口
      */
-    @Test
     public void functionInterfaceTest() {
         List<String> skills = Arrays.asList("java", "golang", "c++", "c", "python");
         Predicate<String> length4 = (str) -> str.length() > 4;
@@ -75,7 +72,6 @@ public void filterByFilter(List list, Predicate condition) {
     /**
      * predicate 的复杂使用
      */
-    @Test
     public void predicateTest() {
         Predicate<String> startsWith = (str) -> str.startsWith("g");
         Predicate<String> length = (str) -> str.length() > 4;
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Lambda.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Lambda.java
@@ -4,7 +4,7 @@
 import lombok.Getter;
 import lombok.Setter;
 import lombok.ToString;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import java.util.*;
 import java.util.stream.Collectors;
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8LocalDateTime.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8LocalDateTime.java
@@ -6,7 +6,7 @@
 import java.time.temporal.TemporalAdjusters;
 import java.util.Date;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * <p>
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8NashornJs.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8NashornJs.java
@@ -1,12 +1,10 @@
 package com.wdbyte;
 
-import org.junit.Test;
-
 import javax.script.ScriptEngine;
 import javax.script.ScriptEngineManager;
 import javax.script.ScriptException;
-import java.util.HashSet;
-import java.util.Set;
+
+import org.junit.jupiter.api.Test;
 
 /**
  * <p>
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Optional.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Optional.java
@@ -2,9 +2,9 @@
 
 import java.util.Optional;
 
-import org.junit.Test;
 
 import lombok.Data;
+import org.junit.jupiter.api.Test;
 
 /**
  * <p>
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Stream.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8Stream.java
@@ -1,7 +1,6 @@
 package com.wdbyte;
 
-import org.junit.Test;
-
+import org.junit.jupiter.api.Test;
 import java.io.BufferedReader;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8StreamPro.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/Jdk8StreamPro.java
@@ -6,8 +6,7 @@
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.stream.Stream;
-
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author darcy
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator.java
@@ -0,0 +1,66 @@
+package com.wdbyte.comparator;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author niulang
+ * @date 2022/04/02
+ */
+public class Java8Comparator {
+    public static void main(String[] args) {
+        List<Person> list = new ArrayList<>();
+        list.add(new Person("Linda", 10));
+        list.add(new Person("Jack", 30));
+        list.add(new Person("Chris", 20));
+        sortListJava7(list);
+    }
+
+    private static void sortListJava7(List<Person> list) {
+        Collections.sort(list, new Comparator<Person>() {
+            @Override
+            public int compare(Person o1, Person o2) {
+                return o1.getAge() - o2.getAge();
+            }
+        });
+        for (Person person : list) {
+            System.out.println(person);
+        }
+    }
+}
+
+class Person {
+    private String name;
+    private Integer age;
+
+    public Person(String name, Integer age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    @Override
+    public String toString() {
+        return "Person{" +
+            "name='" + name + '\'' +
+            ", age=" + age +
+            '}';
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+}
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator2.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator2.java
@@ -0,0 +1,29 @@
+package com.wdbyte.comparator;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author niulang
+ * @date 2022/04/02
+ */
+public class Java8Comparator2 {
+    public static void main(String[] args) {
+        List<Person> list = new ArrayList<>();
+        list.add(new Person("Chris", 20));
+        list.add(new Person("Linda", 10));
+        list.add(new Person("Jack", 30));
+        sort(list);
+        list.forEach(System.out::println);
+    }
+
+    private static List<Person> sort(List<Person> list) {
+        //Comparator<Person> byAge = (Person o1, Person o2) -> o1.getAge().compareTo(o2.getAge());
+        Comparator<Person> byAge = Comparator.comparing(Person::getAge);
+        list.sort(byAge);
+        return list;
+    }
+}
+
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator3.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator3.java
@@ -0,0 +1,28 @@
+package com.wdbyte.comparator;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author niulang
+ * @date 2022/04/02
+ */
+public class Java8Comparator3 {
+    public static void main(String[] args) {
+        List<Person> list = new ArrayList<>();
+        list.add(new Person("Chris", 20));
+        list.add(new Person("Linda", 10));
+        list.add(new Person("Jack", 30));
+        sort(list);
+        for (Person person : list) {
+            System.out.println(person);
+        }
+    }
+
+    private static List<Person> sort(List<Person> list) {
+        list.sort(Comparator.comparing(Person::getAge));
+        return list;
+    }
+}
+
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator4.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator4.java
@@ -0,0 +1,28 @@
+package com.wdbyte.comparator;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author niulang
+ * @date 2022/04/02
+ */
+public class Java8Comparator4 {
+    public static void main(String[] args) {
+        List<Person> list = new ArrayList<>();
+        list.add(new Person("Chris", 20));
+        list.add(new Person("Linda", 10));
+        list.add(new Person("Jack", 30));
+        sort(list);
+        for (Person person : list) {
+            System.out.println(person);
+        }
+    }
+
+    private static List<Person> sort(List<Person> list) {
+        list.sort(Comparator.comparing(Person::getName));
+        return list;
+    }
+}
+
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator5.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator5.java
@@ -0,0 +1,30 @@
+package com.wdbyte.comparator;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author niulang
+ * @date 2022/04/02
+ */
+public class Java8Comparator5 {
+    public static void main(String[] args) {
+        List<Person> list = new ArrayList<>();
+        list.add(new Person("Chris", 20));
+        list.add(new Person("Linda", 10));
+        list.add(new Person("Jack", 30));
+        Collections.sort(list, new Comparator<Person>() {
+            @Override
+            public int compare(Person o1, Person o2) {
+                return o1.getAge() - o2.getAge();
+            }
+        });
+        for (Person person : list) {
+            System.out.println(person);
+        }
+    }
+
+}
+
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator6.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator6.java
@@ -0,0 +1,36 @@
+package com.wdbyte.comparator;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author niulang
+ * @date 2022/04/02
+ */
+public class Java8Comparator6 {
+    public static void main(String[] args) {
+        List<Person> list = new ArrayList<>();
+        list.add(new Person("Chris", 20));
+        list.add(new Person("Linda", 10));
+        list.add(new Person("Jack", 30));
+
+        Comparator<Person> comparing = Comparator.comparing(Person::getAge);
+        list.sort(comparing);
+        list.forEach(System.out::println);
+
+        System.out.println("--------");
+
+        list.sort(comparing.reversed());
+        list.forEach(System.out::println);
+
+        list.sort((p1, p2) -> p1.getAge() - p2.getAge());
+        list.forEach(System.out::println);
+        System.out.println("--------");
+        list.sort((p1, p2) -> p2.getAge() - p1.getAge());
+        list.forEach(System.out::println);
+    }
+
+}
+
diff --git a/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator7.java b/core-java-modules/core-java-8/src/main/java/com/wdbyte/comparator/Java8Comparator7.java
@@ -0,0 +1,28 @@
+package com.wdbyte.comparator;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author niulang
+ * @date 2022/04/02
+ */
+public class Java8Comparator7 {
+    public static void main(String[] args) {
+        List<com.wdbyte.comparator.Person> list = new ArrayList<>();
+        list.add(new com.wdbyte.comparator.Person("Chris", 20));
+        list.add(new com.wdbyte.comparator.Person("Linda", 10));
+        list.add(new com.wdbyte.comparator.Person("Jack", 30));
+
+        list.stream()
+            .sorted(Comparator.comparing(Person::getAge))
+            .forEach(System.out::println);
+        System.out.println("----------");
+        list.stream()
+            .sorted(Comparator.comparing(Person::getAge).reversed())
+            .forEach(System.out::println);
+    }
+
+}
+
