1. lambda表达式 案例

#bysocket

Author: JeffLi1993

README.md

@@ -33,6 +33,7 @@ Java核心技术学习代码兼测试案例<br>
 	├── org.javacore.thread		// Java 线程
     =================实战JAVA 8=================
     ├── org.javacore.lambda		// lambda表达式
+    ├── org.javacore.stream		// Stream API 集合的流式操作
 	│
 	拼命更新！顶！d=====(￣▽￣*)b
 

src/org/javacore/lambda/LambdaTest01.java renamed to src/org/javacore/lambda/LambdaListCompare.java

@@ -1,14 +1,30 @@
 package org.javacore.lambda;
 
+/*
+ * Copyright [2015] [Jeff Lee]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 import java.util.ArrayList;
 import java.util.List;
 
 /**
  * List 比较器
- * <p/>
+ *
  * Created by bysocket on 16/7/12.
  */
-public class LambdaTest01 {
+public class LambdaListCompare {
     public static void main(String[] args) {
         List<Integer> list = new ArrayList<>();
         list.add(4);

src/org/javacore/lambda/LambdaOperators.java

@@ -0,0 +1,51 @@
+package org.javacore.lambda;
+
+/*
+ * Copyright [2015] [Jeff Lee]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * Lambda 操作符
+ *
+ * Created by bysocket on 16/7/13.
+ */
+public class LambdaOperators {
+    public static void main(String[] args) {
+        List<String> list = new ArrayList<>();
+        list.add("aaa");
+        list.add("cccc");
+        list.add("b");
+        list.add("eeeee");
+
+        /**
+         * :: 操作符格式 => 三种情况
+         *    对象::实例方法
+         *    类::静态方法
+         *    类::实例方法 对于前两种情况，方法引用就是对参数执行该方法。比如下面两种方法
+         */
+        // 按字符串大小排序忽略大小写
+        list.sort(String::compareToIgnoreCase);
+        // 打印 list 元素
+        list.forEach(System.out::println);
+
+        System.out.println("======按字符大小排序======");
+        list.sort(Comparator.comparing(String::length));
+        list.forEach(System.out::println);
+    }
+}

src/org/javacore/lambda/LambdaRunnable.java

@@ -1,12 +1,40 @@
 package org.javacore.lambda;
 
+/*
+ * Copyright [2015] [Jeff Lee]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 /**
+ * Lambda - 启动线程
+ *
  * Created by bysocket on 16/7/13.
  */
 public class LambdaRunnable {
     static int b = 10;
 
     public static void main(String[] args) {
+        // 启动线程
+//        Thread thread = new Thread(new Runnable() {
+//            @Override
+//            public void run() {
+//                b++;
+//                System.out.println(b);
+//            }
+//        });
+
+        // Lambda - 启动线程
         Thread thread = new Thread(() -> {
             b++;
             System.out.println(b);

src/org/javacore/lambda/LambdaTest02.java

@@ -1,4 +1,5 @@
-package org.javacore.scheduler; /*
+package org.javacore.scheduler;
+/*
  * Copyright [2015] [Jeff Lee]
  *
  * Licensed under the Apache License, Version 2.0 (the "License");

src/org/javacore/scheduler/TimerTest.java

@@ -0,0 +1,33 @@
+package org.javacore.stream;
+
+/*
+ * Copyright [2015] [Jeff Lee]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ *
+ * Created by bysocket on 16/7/14.
+ */
+public class CollectStreamTest {
+    public static void main(String[] args) {
+        List<Integer> list = Arrays.asList(1,2,3,4);
+        Double result = list.stream().collect(Collectors.averagingDouble(d->d*2));
+        System.out.println(result);
+    }
+}

src/org/javacore/stream/CollectStreamTest.java

@@ -0,0 +1,79 @@
+package org.javacore.stream;
+
+/*
+ * Copyright [2015] [Jeff Lee]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * Stream API 集合的流式操作
+ *
+ * Created by bysocket on 16/7/13.
+ */
+public class CollectionStreamTest {
+    public static void main(String[] args) {
+        List<String> list = new ArrayList<>();
+        list.add("aa");
+        list.add("cccc");
+        list.add("bbb");
+
+        /**
+         * Stream的使用:
+         *  创建/获取流 -> 中间操作（过滤、转换等） -> 终止操作（ 聚合、收集结果）
+         */
+        list.stream().forEach(System.out::println);
+        System.out.println();
+
+        /**
+         * 过滤
+         *      collect语法 {@link StreamCollectTest}
+         */
+        List list0 = list.stream().filter(str -> str.startsWith("cc")).collect(Collectors.toList());
+        List list1 = list.stream().filter(str -> str.startsWith("aa")).collect(Collectors.toList());
+
+        list0.stream().forEach(System.out::println);
+        list1.stream().forEach(System.out::println);
+        System.out.println();
+
+        /**
+         * 转换
+         */
+        List list2 = list.stream().map(str -> str.replace("c","*")).collect(Collectors.toList());
+
+        list2.stream().forEach(System.out::println);
+        System.out.println();
+
+        /**
+         * 提取
+         *      从skip开始至limit位置为止
+         */
+        List list3 = list.stream().skip(0).limit(1).collect(Collectors.toList());
+
+        list3.stream().forEach(System.out::println);
+        System.out.println();
+
+        /**
+         * 组合
+         */
+        List list4 = Stream.concat(list.stream(),list.stream()).collect(Collectors.toList());
+
+        list4.stream().forEach(System.out::println);
+        System.out.println();
+    }
+}

src/org/javacore/stream/CollectionStreamTest.java

@@ -0,0 +1,38 @@
+package org.javacore.stream;
+
+/*
+ * Copyright [2015] [Jeff Lee]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Stream API 集合的流式操作
+ * <p/>
+ * Created by bysocket on 16/7/13.
+ */
+public class CollectionStreamTest01 {
+    public static void main(String[] args) {
+        List<String> strList = Arrays.asList("a1", "a2", "c3", "c6", "c4");
+
+        strList
+                .stream()
+                .filter(str -> str.startsWith("c"))
+                .map(String::toUpperCase)
+                .sorted()
+                .forEach(System.out::println);
+    }
+}

src/org/javacore/stream/CollectionStreamTest01.java

@@ -0,0 +1,38 @@
+package org.javacore.stream;
+
+/*
+ * Copyright [2015] [Jeff Lee]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * 组合 - 流
+ *
+ * Created by bysocket on 16/7/14.
+ */
+public class ConcatStreamTest {
+    public static void main(String[] args) {
+        List<String> list1 = Arrays.asList("a","b","c");
+        List<String> list2 = Arrays.asList("d","e","f");
+
+        // 组合list1和list2的流
+        List result = Stream.concat(list1.stream(),list2.stream()).collect(Collectors.toList());
+        result.stream().forEach(System.out::println);
+    }
+}