lamdasamples

.gitignore

@@ -0,0 +1,18 @@
+# Generated by http://gitignore.io
+
+### IntelliJ ###
+*.iml
+*.ipr
+*.iws
+.idea/
+
+### Java ###
+*.class
+
+# Package Files #
+*.jar
+*.war
+*.ear
+
+### Maven ###
+target/

README.md

@@ -0,0 +1,51 @@
+## JDK8 Lambda Samples
+originally created by [@shipilev](https://github.com/shipilev), [repo](https://github.com/shipilev/jdk8-lambda-samples)
+
+#### short notes:
+
+| class | test | description |
+|---|---|---|
+| LambdaTest | testCmpLegacy/testCmpLambda0 | Comparators: lambdas and anonymous classes
+||testCmpLambda1| (int x)->
+||testOneArg| ()->()
+||testOneArg1 & 2| (x)-> aka x->
+||testCmpLambda2 & 3| Integer bigger than 127
+||testConsumer | Consumer in .forEach()
+|UroborosTest| \* | chain call
+|CaptureTest|testLegacy | final fields in anonymous class
+||testLambda | *effective final* with lambda
+||testPredicate1 & 2| Predicates with context
+|ScopingTest|testScoping1| different **this** for anonymous classes and lambdas
+|FibonacciTest| test10 | capture **this** but not field
+|| test10_static| without capture, just link to static method
+|MethodRefTest| testMethodRefStatic| methodRef to static method (as prev)
+||testMethodRefInstance0 & 1 & 2 | *bound* MethodRef
+||testMethodRefInstanceUnbound | *unbound* MethodRef (add **this**)
+||testConstructor | call **new**
+||testConstructor0 | constructor w/o parameters
+||testConstructor1 | constructor w/ parameters
+|ZamTest| \* | Replace lambdas to MethodRef
+|ThreadLocalTest|threadLocalLegacy| legacy variant
+||threadLocalLambda| added method withInitial(Supplier)
+||threadLocalMRef | via MethodRef
+| ▼ Advanced ▼
+|NoiseSampleTest|
+|WeirdFunctionTest|
+
+###Default Methods
+
+| class | test | description |
+|---|---|---|
+|DefaultTest| \* | backward compatibility
+|GuavaTest| testTreeMultiset | usage with third party libraries
+|StaticInterfaceTest| test | functional interface with static method
+
+###Streams (Bulk Operations for Collections)
+
+| class | test | description |
+|---|---|---|
+|ExternalInternalTest| \* |  
+||►|highlight the difference between internal and external iteration
+||►|iteration is explicitly serial
+||►|libraries have more headroom optimizing with internal iteration
+||►|sometimes even forEach is not enough: chaining the action within the serial again

pom.xml

@@ -31,7 +31,7 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.8.1</version>
+            <version>4.11</version>
             <scope>test</scope>
         </dependency>
         <dependency>

src/test/java/net/openjdk/defaults/DefaultTest.java

@@ -1,25 +1,17 @@
 package net.openjdk.defaults;
 
-import junit.framework.Assert;
 import org.junit.Test;
 
-public class DefaultTest {
-
-    @Test
-    public void testNew() {
-        Assert.assertEquals("Legacy Method from the New Class", new NewClass().legacyMethod());
-        Assert.assertEquals("New Method from the New Class", new NewClass().newMethod());
-    }
+import static org.junit.Assert.assertEquals;
 
-    @Test
-    public void testLegacy() {
-        Assert.assertEquals("Legacy Method from the Legacy Class", new LegacyClass().legacyMethod());
-        Assert.assertEquals("The beauty is in the eye of the defender", new LegacyClass().newMethod());
-    }
+public class DefaultTest {
 
     public interface LegacyInterface {
         String legacyMethod();
-        default String newMethod() { return "The beauty is in the eye of the defender"; }
+
+        default String newMethod() {
+            return "The beauty is in the eye of the defender";
+        }
     }
 
     public class LegacyClass implements LegacyInterface {
@@ -41,4 +33,16 @@ public String newMethod() {
         }
     }
 
+    @Test
+    public void testLegacy() {
+        assertEquals("Legacy Method from the Legacy Class", new LegacyClass().legacyMethod());
+        assertEquals("The beauty is in the eye of the defender", new LegacyClass().newMethod());
+    }
+
+    @Test
+    public void testNew() {
+        assertEquals("Legacy Method from the New Class", new NewClass().legacyMethod());
+        assertEquals("New Method from the New Class", new NewClass().newMethod());
+    }
+
 }

src/test/java/net/openjdk/defaults/GuavaTest.java

@@ -1,9 +1,10 @@
 package net.openjdk.defaults;
 
 import com.google.common.collect.TreeMultiset;
-import junit.framework.Assert;
 import org.junit.Test;
 
+import static org.junit.Assert.*;
+
 public class GuavaTest {
 
     @Test
@@ -14,7 +15,7 @@ public void testTreeMultiset() {
         strings.add("Baz");
 
         String result = strings.stream().reduce((s1, s2) -> s1 + ", " + s2).get();
-        Assert.assertEquals("Bar, Baz, Foo", result);
+        assertEquals("Bar, Baz, Foo", result);
     }
 
 }

src/test/java/net/openjdk/defaults/StaticInterfaceTest.java

@@ -1,15 +1,14 @@
 package net.openjdk.defaults;
 
-import org.junit.Assert;
-import org.junit.Ignore;
 import org.junit.Test;
 
+import static org.junit.Assert.*;
+
 public class StaticInterfaceTest {
 
     @Test
     public void test() {
-        // FIXME: does not run with current public builds
-        Assert.assertEquals("toDublin", TicketOffice.defaultOffice().qDublin());
+        assertEquals("toDublin", TicketOffice.defaultOffice().qDublin());
     }
 
     public interface TicketOffice {

src/test/java/net/openjdk/lambda/CaptureTest.java

@@ -1,18 +1,20 @@
 package net.openjdk.lambda;
 
-import junit.framework.Assert;
 import org.junit.Test;
 
 import java.util.Comparator;
+import java.util.function.Function;
 import java.util.function.Predicate;
 
+import static org.junit.Assert.*;
+
 public class CaptureTest {
 
     @Test
     public void testLegacy() {
         final int minus_one = -1;
         final int zero = 0;
-        final int one  = 1;
+        final int one = 1;
 
         Comparator<Integer> cmp = new Comparator<Integer>() {
             @Override
@@ -22,36 +24,43 @@ public int compare(Integer x, Integer y) {
 
         };
 
-        Assert.assertEquals(0,  cmp.compare(0, 0));
-        Assert.assertEquals(-1, cmp.compare(-100, 100));
-        Assert.assertEquals(1,  cmp.compare(100, -100));
+        assertEquals(0, cmp.compare(0, 0));
+        assertEquals(-1, cmp.compare(-100, 100));
+        assertEquals(1, cmp.compare(100, -100));
     }
 
     @Test
     public void testLambda() {
         int minus_one = -1;
         int zero = 0;
-        int one  = 1;
+        int one = 1;
 
         Comparator<Integer> cmp = (x, y) -> (x < y) ? minus_one : ((x > y) ? one : zero);
 
-        Assert.assertEquals(0,  cmp.compare(0, 0));
-        Assert.assertEquals(-1, cmp.compare(-100, 100));
-        Assert.assertEquals(1,  cmp.compare(100, -100));
+        assertEquals(0, cmp.compare(0, 0));
+        assertEquals(-1, cmp.compare(-100, 100));
+        assertEquals(1, cmp.compare(100, -100));
     }
 
-
     private Predicate<String> makeCaseUnsensitiveMatcher(String pattern) {
         return s -> pattern.equalsIgnoreCase(s);
     }
 
     @Test
-    public void testLambda1() {
+    public void testPredicate1() {
         // Predicate<T>   ~  boolean test(T t);
-        Assert.assertTrue( makeCaseUnsensitiveMatcher("true").test("TruE") );
-        Assert.assertTrue( makeCaseUnsensitiveMatcher("false").test("FalsE") );
-        Assert.assertFalse(makeCaseUnsensitiveMatcher("true").test("FalsE") );
+        assertTrue(makeCaseUnsensitiveMatcher("true").test("TruE"));
+        assertTrue(makeCaseUnsensitiveMatcher("false").test("FalsE"));
+        assertFalse(makeCaseUnsensitiveMatcher("true").test("FalsE"));
+    }
+
+    @Test
+    public void testPredicate2() {
+        Function<String, Predicate<String>> matcher = s1 -> s2 -> s1.equalsIgnoreCase(s2);
 
+        assertTrue(matcher.apply("true").test("TruE"));
+        assertTrue(matcher.apply("false").test("FalsE"));
+        assertFalse(matcher.apply("true").test("FalsE"));
     }
 
 }

src/test/java/net/openjdk/lambda/FibonacciTest.java

@@ -1,35 +1,36 @@
 package net.openjdk.lambda;
 
-import junit.framework.Assert;
 import org.junit.Test;
 
 import java.util.function.IntUnaryOperator;
 
+import static org.junit.Assert.*;
+
 public class FibonacciTest {
 
     // Фибоначчийн тоог хүн төрөлхтөн өөрсдийн ахуй (source: Wikipedia MN)
-    private IntUnaryOperator fib =
-            (n) -> (n < 2) ? n : fib.applyAsInt(n - 1) + fib.applyAsInt(n - 2);
+    private IntUnaryOperator fib;
+    {fib = (n) -> (n < 2) ? n : fib.applyAsInt(n - 1) + fib.applyAsInt(n - 2);}
 
     @Test
     public void test10() {
-        Assert.assertEquals(55, fib.applyAsInt(10));
+        assertEquals(55, fib.applyAsInt(10));
     }
 
-    private static IntUnaryOperator fib_static =
-            (n) -> (n < 2) ? n : fib_static.applyAsInt(n - 1) + fib_static.applyAsInt(n - 2);
+    private static IntUnaryOperator fib_static;
+    static {fib_static = (n) -> (n < 2) ? n : fib_static.applyAsInt(n - 1) + fib_static.applyAsInt(n - 2);}
 
     @Test
     public void test10_static() {
-        Assert.assertEquals(55, fib_static.applyAsInt(10));
+        assertEquals(55, fib_static.applyAsInt(10));
     }
 
 //    @Test
 //    public void test10_bad() { // should not compile
 //        IntUnaryOperator fib =
 //                (n) -> (n < 2) ? n : fib.operate(n - 1) + fib.operate(n - 2);
 //
-//        Assert.assertEquals(55, fib.operateAsInt(10));
+//        assertEquals(55, fib.operateAsInt(10));
 //    }
 
 }