Add java8-features module: runnable demos and captured output for the ankurm.com java8-features article

2026-10-20 17:13:58 +00:00
parent d565be93c6
commit 77c782abbf
18 changed files with 250 additions and 0 deletions
@@ -0,0 +1,7 @@
+$ javac src/LambdaDemo.java && java LambdaDemo     (1.8.0_504)
+anonymous class : [Zoya, Meera, Ankur, Bhaskar]
+lambda          : [Ankur, Bhaskar, Meera, Zoya]
+method reference: [Ankur, Bhaskar, Meera, Zoya]
+captured base   : 15
+lambda this      : LambdaDemo
+anonymous this   : LambdaDemo$2
@@ -0,0 +1,8 @@
+$ javac src/StreamsDemo.java && java StreamsDemo     (1.8.0_504)
+distinct+upper  : [STREAM, LAMBDA, OPTIONAL, DEFAULT, TIME]
+sum of lengths  : 37
+pipeline built, nothing printed yet
+  filtering stream
+first match     : stream
+reuse           : stream has already been operated upon or closed
+groupingBy      : {long=[stream, lambda, optional, default], short=[time]}
@@ -0,0 +1,8 @@
+$ javac src/OptionalDemo.java && java OptionalDemo     (1.8.0_504)
+present         : VALUE-1
+absent          : none
+orElse (value present):
+  expensive() called
+orElseGet (value present):
+get() on empty  : No value present
+Optional.of(null): NullPointerException
@@ -0,0 +1,3 @@
+$ javac src/DefaultMethodsDemo.java && java DefaultMethodsDemo     (1.8.0_504)
+diamond resolved: walk + swim
+default + static: Hello, Ankur
@@ -0,0 +1,8 @@
+$ javac src/TimeDemo.java && java TimeDemo     (1.8.0_504)
+plusMonths      : 2026-11-20  (original still 2026-10-20)
+end of month    : 2026-02-28
+days between    : 292
+Period          : P6Y7M21D
+Duration        : PT2H15M
+same instant NY : 2026-10-20 13:05 EDT
+old Date month  : new java.util.Date(126, 9, 20) -> month index 9 (October is 9)
@@ -0,0 +1,7 @@
+$ javac src/FunctionalInterfacesDemo.java && java FunctionalInterfacesDemo     (1.8.0_504)
+andThen         : 11
+compose         : 12
+negate          : true
+Supplier        : supplied
+BiFunction      : 7
+UnaryOperator   : OK
@@ -0,0 +1,11 @@
+$ javac broken/CaptureError.java     (1.8.0_504)
+broken/CaptureError.java:7: error: local variables referenced from a lambda expression must be final or effectively final
+        Supplier<Integer> s = () -> counter;
+                                    ^
+1 error
+
+$ javac broken/DiamondError.java     (1.8.0_504)
+broken/DiamondError.java:5: error: class C inherits unrelated defaults for move() from types A and B
+    static class C implements A, B { }
+           ^
+1 error