更新 java 8 特性

code/src/main/java/com/raorao/Test.java

@@ -1,5 +1,21 @@
 package com.raorao;
 
+import afu.org.checkerframework.checker.igj.qual.I;
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.PriorityQueue;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingDeque;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentLinkedDeque;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.DelayQueue;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.PriorityBlockingQueue;
+
 /**
  * .
  *
@@ -14,6 +30,13 @@ public class Test {
     //System.out.println(foo());
     int r = new Test().foo();
     System.out.println(r);
+    PriorityBlockingQueue<Integer> aa;
+    LinkedBlockingQueue<Integer> ss;
+    ss = new LinkedBlockingQueue<>();
+    ss.add(1);
+    ArrayBlockingQueue<Integer> s;
+    LinkedBlockingQueue<Integer> a;
+
   }
 
   public int foo() {

code/src/main/java/com/raorao/java/base/LambdaTest.java

@@ -0,0 +1,46 @@
+package com.raorao.java.base;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Supplier;
+
+/**
+ * Lambda 表达式.
+ *
+ * @author Xiong Raorao
+ * @since 2018-08-06-17:32
+ */
+public class LambdaTest {
+
+  public static void main(String[] args) {
+    foo1();
+  }
+
+  public static void foo1() {
+    String[] ss = new String[] {"a", "c", "b", "d"};
+    List<String> list = Arrays.asList(ss);
+    list.forEach(e -> System.out.print(e));
+    System.out.println();
+    list.sort((e1, e2) -> e2.compareTo(e1));
+    list.forEach(System.out::print);
+    System.out.println();
+    Map<Integer, Integer> map = new HashMap<>();
+    for (int i = 0; i < 5; i++) {
+      map.put(i, i * i);
+    }
+    map.forEach((k, v) -> System.out.println("key = " + k + ", value = " + v));
+
+    Thread t = new Thread(()->{
+      System.out.println(  "start thread");
+      try {
+        Thread.sleep(2000);
+      } catch (InterruptedException e) {
+        e.printStackTrace();
+      }
+      System.out.println("end thread");
+    });
+    t.start();
+  }
+}

code/src/main/java/com/raorao/java/base/StreamTest.java

@@ -0,0 +1,92 @@
+package com.raorao.java.base;
+
+
+import java.awt.image.BufferedImage;
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileReader;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.Random;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * java 8 Stream.
+ *
+ * @author Xiong Raorao
+ * @since 2018-08-06-17:29
+ */
+public class StreamTest {
+
+  public static void main(String[] args) {
+    Stream<String> stream = Stream.of("a", "b", "c");
+    List<String> list = Arrays.asList("hello", "world");
+    List<Integer> intList = Arrays.asList(1, 3, 12, 4, 8, 9, -1);
+
+    // 大写
+    List<String> uppercase = list.stream().map(String::toUpperCase)
+        .collect(Collectors.toList()); // 类实例的方法引用，没有传入参数
+    List<String> uppercase2 = list.stream().map((e) -> e + "a").collect(Collectors.toList());
+    uppercase.forEach(System.out::println);
+    uppercase2.forEach(System.out::println);
+
+    // 平方数
+    List<Integer> square = intList.stream().map((e) -> e * e).collect(Collectors.toList());
+    square.forEach((e) -> System.out.print(e + " "));
+    System.out.println();
+
+    // 一对多
+    Stream<List<Integer>> inputStream = Stream.of(
+        Arrays.asList(1),
+        Arrays.asList(2, 3),
+        Arrays.asList(4, 5, 6)
+    );
+    Stream<Integer> outputStream = inputStream.
+        flatMap((childList) -> childList.stream());
+    outputStream.forEach(e -> System.out.print(e + " "));
+
+    // 过滤器
+    // 1. 选择偶数
+    List<Integer> evenNumber = intList.stream().filter(e -> e % 2 == 0)
+        .collect(Collectors.toList());
+    evenNumber.forEach((e) -> System.out.print(e + " "));
+    System.out.println();
+
+    // 2. find first
+    //intList = new ArrayList<>();
+    Optional<Integer> first = intList.stream().findFirst();
+    System.out.println(first.orElse(0));
+
+    /**
+     * reduce, 组合元素。
+     * 它提供一个起始值（种子），然后依照运算规则（BinaryOperator），
+     * 和前面 Stream 的第一个、第二个、第 n 个元素组合。从这个意义上说，字符串拼接、数值的 sum、min、max、average 都是特殊的 reduce。
+     */
+    // 1. 字符串拼接
+    Optional<String> ss = stream.reduce((a, b) -> a + b);
+    System.out.println(ss.orElse(null));
+    //String s2 = stream.reduce("", (a, b) -> a + b + "-");
+    //System.out.println(s2);
+
+    // 2. 数值相加
+    Optional<Integer> sum = intList.stream().reduce((a, b) -> a + b);
+    System.out.println(sum.orElse(0));
+
+    // 3. min
+    int min = intList.stream().mapToInt(e->e).min().getAsInt();
+    System.out.println("min: " + min);
+
+    // 自己生成流
+    Stream.iterate(0, n -> n +3).limit(10).forEach((e) -> System.out.print(e + " "));
+    // 生成随机数
+    Random seed = new Random();
+    Supplier<Integer> random = seed::nextInt;
+    Stream.generate(random).limit(10).forEach(System.out::println);
+
+  }
+
+}