lambda

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/collection/CollectionFactory.java

+package org.hongxi.whatsmars.base.lambda.collection;
+
+import java.util.function.Supplier;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public interface CollectionFactory {
+
+    static MyCollection create(Supplier<MyCollection> supplier) {
+        return supplier.get();
+    }
+}

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/collection/MyCollection.java

+package org.hongxi.whatsmars.base.lambda.collection;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public interface MyCollection {
+
+    int size();
+
+    default String notRequired() {
+        return "Default implementation";
+    }
+}

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/collection/MyList.java

+package org.hongxi.whatsmars.base.lambda.collection;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public class MyList implements MyCollection {
+    @Override
+    public int size() {
+        return 0;
+    }
+}

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/collection/NewList.java

+package org.hongxi.whatsmars.base.lambda.collection;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public class NewList implements MyCollection {
+    @Override
+    public int size() {
+        return 0;
+    }
+
+    @Override
+    public String notRequired() {
+        return "Overridden implementation";
+    }
+}

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/collection/Test.java

+package org.hongxi.whatsmars.base.lambda.collection;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public class Test {
+    public static void main(String[] args) {
+        MyCollection collection = CollectionFactory.create(MyList::new);
+        System.out.println(collection.notRequired());
+
+        collection = CollectionFactory.create(NewList::new);
+        System.out.println(collection.notRequired());
+    }
+}

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/stream/Status.java

+package org.hongxi.whatsmars.base.lambda.stream;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public enum Status {
+    OPEN, CLOSED
+}

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/stream/Task.java

+package org.hongxi.whatsmars.base.lambda.stream;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public class Task {
+    private Status status;
+    private int point;
+
+    public Task() {
+    }
+
+    public Task(Status status, int point) {
+        this.status = status;
+        this.point = point;
+    }
+
+    public Status getStatus() {
+        return status;
+    }
+
+    public void setStatus(Status status) {
+        this.status = status;
+    }
+
+    public int getPoint() {
+        return point;
+    }
+
+    public void setPoint(int point) {
+        this.point = point;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("(%s, %d)", status, point);
+    }
+}

whatsmars-javase-example/src/main/java/org/hongxi/whatsmars/base/lambda/stream/Test.java

+package org.hongxi.whatsmars.base.lambda.stream;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+/**
+ * Created by shenhongxi on 2018/1/11.
+ */
+public class Test {
+    public static void main(String[] args) {
+        Collection<Task> tasks = Arrays.asList(
+                new Task(Status.OPEN, 5),
+                new Task(Status.OPEN, 13),
+                new Task(Status.CLOSED, 8)
+        );
+        int openTaskPoints = tasks
+                .stream()
+                .filter(task -> task.getStatus() == Status.OPEN)
+                .mapToInt(Task::getPoint)
+                .sum();
+        System.out.println(openTaskPoints);
+
+        final int totalPoints = tasks
+                .stream()
+                .parallel()
+                .map(Task::getPoint)
+                .reduce(0, Integer::sum);
+        System.out.println(totalPoints);
+
+        Map<Status, List<Task>> map = tasks.stream().collect(Collectors.groupingBy(Task::getStatus));
+        System.out.println(map);
+
+        Collection<String> result = tasks
+                .stream()
+                .mapToInt(Task::getPoint)
+                .mapToDouble(point -> point * 100 / totalPoints)
+                .mapToObj(percentage -> (int) percentage + "%")
+                .collect(Collectors.toList());
+        System.out.println(result);
+    }
+}

whatsmars-javase-example/src/test/java/org/hongxi/whatsmars/base/lambda/LambdaTest.java

@@ -2,13 +2,109 @@ package org.hongxi.whatsmars.base.lambda;
 
 import org.junit.Test;
 
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+import java.nio.charset.StandardCharsets;
+import java.time.*;
+import java.util.*;
+import java.util.concurrent.ThreadLocalRandom;
+
 /**
- * Created by javahongxi on 2017/6/24.
+ * Created by javahongxi on 2018/1/2.
  */
 public class LambdaTest {
 
     @Test
-    public void t1() {
-        new Thread(() -> System.out.println("hi,lambda!")).start();
+    public void t() {
+        new Thread(() -> System.out.println("Hi, I am lambda!")).start();
+        System.out.println("main thread ...");
+    }
+
+    @Test
+    public void t2() {
+        Arrays.asList("a", "b", "c").forEach(e -> System.out.println(e));
+    }
+
+    @Test
+    public void t3() {
+        Arrays.asList("a", "b", "c").forEach(e -> {
+            System.out.println(System.currentTimeMillis());
+            System.out.println(e);
+        });
+    }
+
+    @Test
+    public void t4() {
+        List<String> names = new ArrayList<>();
+        names.add("d");
+        names.add("a");
+        names.add("ax");
+        names.add("bbb");
+        names.sort(String::compareTo);
+        System.out.println(names);
+    }
+
+    @Test
+    public void t5() {
+        Optional<String> fullName = Optional.ofNullable(null);
+        System.out.println("Full Name is set? " + fullName.isPresent());
+        System.out.println("Full Name: " + fullName.orElseGet(() -> "[none]"));
+        System.out.println(fullName.map(s -> "Hey " + s + "!").orElse("Hey Stranger!"));
+    }
+
+    @Test
+    public void t6() {
+        long[] arr = new long [20000];
+
+        Arrays.parallelSetAll(arr,
+                index -> ThreadLocalRandom.current().nextInt(1000000));
+        Arrays.stream(arr).limit(10).forEach(
+                i -> System.out.print(i + " "));
+        System.out.println();
+
+        Arrays.parallelSort(arr);
+        Arrays.stream(arr).limit(10).forEach(
+                i -> System.out.print(i + " "));
+        System.out.println();
+    }
+
+    @Test
+    public void t7() {
+        String text = "Base64 finally in Java 8!";
+        String encoded = Base64
+                .getEncoder()
+                .encodeToString(text.getBytes(StandardCharsets.UTF_8));
+        System.out.println(encoded);
+
+        String decoded = new String(Base64.getDecoder().decode(encoded), StandardCharsets.UTF_8);
+        System.out.println(decoded);
+    }
+
+    @Test
+    public void t8() throws ScriptException {
+        ScriptEngineManager manager = new ScriptEngineManager();
+        ScriptEngine engine = manager.getEngineByName("JavaScript");
+        System.out.println(engine.getClass().getName());
+        System.out.println("Result:" + engine.eval("function f() { return 1; }; f() + 1;"));
+    }
+
+    @Test
+    public void t9() {
+        Clock clock = Clock.systemUTC();
+        System.out.println(clock.instant());
+        System.out.println(clock.millis());
+        LocalDate localDate = LocalDate.now(); // LocalDate.now(clock)
+        System.out.println(localDate);
+        LocalTime localTime = LocalTime.now(); // LocalTime.now(clock)
+        System.out.println(localTime);
+        LocalDateTime localDateTime = LocalDateTime.now(); // LocalDateTime.now(clock)
+        System.out.println(localDateTime);
+
+        LocalDateTime from = LocalDateTime.of( 2014, Month.APRIL, 16, 0, 0, 0 );
+        LocalDateTime to = LocalDateTime.of( 2015, Month.APRIL, 16, 23, 59, 59 );
+        Duration duration = Duration.between(from, to);
+        System.out.println("Duration in days: " + duration.toDays());
+        System.out.println("Duration in hours: " + duration.toHours());
     }
 }