update lambda

Author: deleiguo

source/java/interview/delei-interview-java-core/src/main/java/cn/delei/java/feature/FunctionInterfaceDemo.java

@@ -0,0 +1,76 @@
+package cn.delei.java.feature;
+
+import cn.delei.util.PrintUtil;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
+
+/**
+ * 函数式编程Demo
+ *
+ * @author deleiguo
+ * @since 1.8
+ */
+public class FunctionInterfaceDemo {
+    public static void main(String[] args) {
+        jdkFunction();
+    }
+
+    static void jdkFunction() {
+        PrintUtil.printDivider("Consumer");
+        Consumer<String> c1 = System.out::println;
+        Consumer<String> c2 = s -> System.out.println(s + "-Consumer");
+        c1.accept("111");
+        c2.accept("222");
+        c1.andThen(c1).andThen(c2).accept("3333");
+
+        PrintUtil.printDivider("Function");
+        Function<Integer, Integer> f = s -> s * 2;
+        Function<Integer, Integer> g = s -> s + 2;
+        /*
+         * 下面表示在执行F时，先执行G，并且执行F时使用G的输出当作输入。
+         * 相当于以下代码：
+         * Integer a = g.apply(1);
+         * System.out.println(f.apply(a));
+         */
+        System.out.println(f.compose(g).apply(1));
+        /*
+         * 表示执行F的Apply后使用其返回的值当作输入再执行G的Apply；
+         * 相当于以下代码
+         * Integer a = f.apply(1);
+         * System.out.println(g.apply(a));
+         */
+        System.out.println(f.andThen(g).apply(1));
+        // identity方法会返回一个不进行任何处理的Function，即输出与输入值相等；
+        System.out.println(Function.identity().apply("a"));
+
+        PrintUtil.printDivider("Predicate");
+        List<String> strList = Arrays.asList("Java", "JavaScript", "C", "C++", "C#", "PHP", "Go");
+        Predicate<String> conditon = (str) -> str.length() > 6;
+        filter(strList, conditon);
+        filter(strList, s -> s.startsWith("C"));
+        Predicate<String> p1 = s -> s.equals("Java");
+        Predicate<String> p2 = s -> s.startsWith("JavaScript");
+        // negate: 用于对原来的Predicate做取反处理；
+        System.out.println(p1.negate().test("JavaScript"));
+        // and: 针对同一输入值，多个Predicate均返回True时返回True，否则返回False；
+        System.out.println(p1.and(p2).test("JavaScript"));
+        // or: 针对同一输入值，多个Predicate只要有一个返回True则返回True，否则返回False
+        System.out.println(p1.or(p2).test("Java"));
+
+        PrintUtil.printDivider("Supplier");
+        Supplier<String> supplier = () -> "sss";
+        System.out.println(supplier.get());
+    }
+
+    static void filter(List<String> list, Predicate<String> predicate) {
+        list.stream().filter((s) -> (predicate.test(s))).forEach((s) -> {
+            System.out.println(s + " #");
+        });
+        System.out.println("");
+    }
+}

source/java/interview/delei-interview-java-core/src/main/java/cn/delei/java/feature/LambdaDemo.java

@@ -4,7 +4,6 @@
 
 import java.util.*;
 import java.util.function.Consumer;
-import java.util.function.Predicate;
 
 /**
  * Lambda 函数编程 Demo
@@ -46,25 +45,7 @@ public void accept(String s) {
         PrintUtil.printDivider("方法引用");
         // ==> 方法引用，由::双冒号操作符标识
         strList.forEach(System.out::println);
-
-        PrintUtil.printDivider("Predicate");
-        // ==> Predicate
-        Predicate<String> conditon = (str) -> str.length() > 4;
-        filter(strList, conditon);
-        conditon = (str) -> str.startsWith("delei");
-        filter(strList, conditon);
-        conditon = (str) -> true;
-        filter(strList, conditon);
-        conditon = (str) -> false;
-        filter(strList, conditon);
     }
-
-    static void filter(List<String> list, Predicate<String> predicate) {
-        list.stream().filter((s) -> (predicate.test(s))).forEach((s) -> {
-            System.out.println(s + " ");
-        });
-    }
-
 }