🍱 add java8 growing code

hellokaton · hellokaton · commit ef3dbf359d66 · 2018-02-08T16:02:25.000+08:00
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Base64Demo.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Base64Demo.java
@@ -0,0 +1,28 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+
+/**
+ * Base64 &#22686;&#24378;
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+public class Base64Demo {
+
+    public static void main(String[] args) {
+        final String text = "Lets Learn Java 8!";
+
+        final String encoded = Base64
+                .getEncoder()
+                .encodeToString(text.getBytes(StandardCharsets.UTF_8));
+        System.out.println(encoded);
+
+        final String decoded = new String(
+                Base64.getDecoder().decode(encoded),
+                StandardCharsets.UTF_8);
+        System.out.println(decoded);
+    }
+
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/DateTimeAPI.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/DateTimeAPI.java
@@ -0,0 +1,60 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import java.time.*;
+
+/**
+ * &#26032;&#30340;&#26085;&#26399;&#26102;&#38388; API
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+public class DateTimeAPI {
+
+    public static void main(String[] args) {
+        // Get the system clock as UTC offset
+        final Clock clock = Clock.systemUTC();
+        System.out.println(clock.instant());
+        System.out.println(clock.millis());
+
+        // Get the local date and local time
+        final LocalDate date          = LocalDate.now();
+        final LocalDate dateFromClock = LocalDate.now(clock);
+
+        System.out.println(date);
+        System.out.println(dateFromClock);
+
+        // Get the local date and local time
+        final LocalTime time          = LocalTime.now();
+        final LocalTime timeFromClock = LocalTime.now(clock);
+
+        System.out.println(time);
+        System.out.println(timeFromClock);
+
+        // Get the local date/time
+        final LocalDateTime datetime          = LocalDateTime.now();
+        final LocalDateTime datetimeFromClock = LocalDateTime.now(clock);
+
+        System.out.println(datetime);
+        System.out.println(datetimeFromClock);
+
+        // Get the zoned date/time
+        final ZonedDateTime zonedDatetime          = ZonedDateTime.now();
+        final ZonedDateTime zonedDatetimeFromClock = ZonedDateTime.now(clock);
+        final ZonedDateTime zonedDatetimeFromZone  = ZonedDateTime.now(ZoneId.of("America/Los_Angeles"));
+
+        System.out.println(zonedDatetime);
+        System.out.println(zonedDatetimeFromClock);
+        System.out.println(zonedDatetimeFromZone);
+
+        // Get duration between two dates
+        final LocalDateTime from = LocalDateTime.of(2014, Month.APRIL, 16, 0, 0, 0);
+        final LocalDateTime to   = LocalDateTime.of(2015, Month.APRIL, 16, 23, 59, 59);
+
+        final Duration duration = Duration.between(from, to);
+        System.out.println("Duration in days: " + duration.toDays());
+        System.out.println("Duration in hours: " + duration.toHours());
+
+
+    }
+
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/DefaulableFactory.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/DefaulableFactory.java
@@ -0,0 +1,10 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import java.util.function.Supplier;
+
+public interface DefaulableFactory {
+    // Interfaces now allow static methods
+    static Integer create(Supplier<Integer> supplier) {
+        return supplier.get();
+    }
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Functional.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Functional.java
@@ -0,0 +1,14 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+/**
+ * &#20989;&#25968;&#24335;&#25509;&#21475;
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+@FunctionalInterface
+public interface Functional {
+
+    void method();
+
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/FunctionalDefaultMethods.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/FunctionalDefaultMethods.java
@@ -0,0 +1,16 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+/**
+ * &#40664;&#35748;&#26041;&#27861;
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+@FunctionalInterface
+public interface FunctionalDefaultMethods {
+
+    void method();
+
+    default void defaultMethod() {
+    }
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Lambda.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Lambda.java
@@ -0,0 +1,17 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import java.util.Arrays;
+
+/**
+ * Lambda &#34920;&#36798;&#24335;
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+public class Lambda {
+
+    public static void main(String[] args) {
+        Arrays.asList("a", "b", "d").forEach(System.out::println);
+
+    }
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/NashornDemo.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/NashornDemo.java
@@ -0,0 +1,22 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+
+/**
+ * Nashorn JavaScript&#24341;&#25806;
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+public class NashornDemo {
+
+    public static void main(String[] args) 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;"));
+    }
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/OptionalDemo.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/OptionalDemo.java
@@ -0,0 +1,26 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import java.util.Optional;
+
+/**
+ * Optional
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+public class OptionalDemo {
+
+    public static void main(String[] args) {
+        Optional<String> fullName = Optional.ofNullable(null);
+        System.out.println("Full Name is set? " + fullName.isPresent());
+        System.out.println("Full Name: " + fullName.orElse("[none]"));
+        System.out.println(fullName.map(s -> "Hey " + s + "!").orElse("Hey Stranger!"));
+
+        Optional<String> firstName = Optional.of("Tom");
+        System.out.println("First Name is set? " + firstName.isPresent());
+        System.out.println("First Name: " + firstName.orElseGet(() -> "[none]"));
+        System.out.println(firstName.map(s -> "Hey " + s + "!").orElse("Hey Stranger!"));
+        System.out.println();
+
+    }
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/ParallelArrays.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/ParallelArrays.java
@@ -0,0 +1,28 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import java.util.Arrays;
+import java.util.concurrent.ThreadLocalRandom;
+
+/**
+ * &#24182;&#34892;&#25968;&#32452;
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+public class ParallelArrays {
+
+    public static void main(String[] args) {
+        long[] arrayOfLong = new long[20000];
+
+        Arrays.parallelSetAll(arrayOfLong,
+                index -> ThreadLocalRandom.current().nextInt(1000000));
+        Arrays.stream(arrayOfLong).limit(10).forEach(
+                i -> System.out.print(i + " "));
+        System.out.println();
+
+        Arrays.parallelSort(arrayOfLong);
+        Arrays.stream(arrayOfLong).limit(10).forEach(
+                i -> System.out.print(i + " "));
+        System.out.println();
+    }
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Streams.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/Streams.java
@@ -0,0 +1,51 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+public class Streams {
+
+    private enum Status {
+        OPEN, CLOSED
+    }
+
+    private static final class Task {
+        private final Status  status;
+        private final Integer points;
+
+        Task(final Status status, final Integer points) {
+            this.status = status;
+            this.points = points;
+        }
+
+        public Integer getPoints() {
+            return points;
+        }
+
+        public Status getStatus() {
+            return status;
+        }
+
+        @Override
+        public String toString() {
+            return String.format("[%s, %d]", status, points);
+        }
+    }
+
+    public static void main(String[] args) {
+        final Collection<Task> tasks = Arrays.asList(
+                new Task(Status.OPEN, 5),
+                new Task(Status.OPEN, 13),
+                new Task(Status.CLOSED, 8)
+        );
+
+        // Calculate total points of all active tasks using sum()
+        final long totalPointsOfOpenTasks = tasks
+                .stream()
+                .filter(task -> task.getStatus() == Status.OPEN)
+                .mapToInt(Task::getPoints)
+                .sum();
+
+        System.out.println("Total points: " + totalPointsOfOpenTasks);
+    }
+}
diff --git a/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/TypeInference.java b/java8-growing/src/main/java/io/github/biezhi/java8/growing/jdk8/TypeInference.java
@@ -0,0 +1,24 @@
+package io.github.biezhi.java8.growing.jdk8;
+
+/**
+ * &#26356;&#22909;&#30340;&#31867;&#22411;&#25512;&#26029;
+ *
+ * @author biezhi
+ * @date 2018/2/8
+ */
+public class TypeInference<T> {
+
+    public static <T> T defaultValue() {
+        return null;
+    }
+
+    public T getOrDefault(T value, T defaultValue) {
+        return (value != null) ? value : defaultValue;
+    }
+
+    public static void main(String[] args) {
+        final TypeInference<String> typeInference = new TypeInference<>();
+        typeInference.getOrDefault("22", TypeInference.defaultValue());
+    }
+
+}
