#2 Added support for orElseGet.

src/main/java/com/github/cbuschka/optional/Optional.java

@@ -69,6 +69,13 @@ public <R> Optional<R> map(Function<? super T, ? extends R> mapFunc)
 		}
 	}
 
+	public T orElseGet(Supplier<? extends T> supplier)
+	{
+		Objects.requireNonNull(supplier);
+
+		return isPresent() ? value : supplier.get();
+	}
+
 	public boolean isEmpty()
 	{
 		return value == null;

src/main/java/com/github/cbuschka/optional/Supplier.java

@@ -0,0 +1,6 @@
+package com.github.cbuschka.optional;
+
+public interface Supplier<T>
+{
+	T get();
+}

src/test/java/com/github/cbuschka/optional/OptionalTest.java

@@ -148,4 +148,39 @@ public String apply(String s)
 
 		assertEquals("bar", result);
 	}
+
+	@Test
+	public void orElseGetOfNonEmptyGivesValue()
+	{
+		Optional<String> given = Optional.of("foo");
+
+		String result = given.orElseGet(new Supplier<String>()
+		{
+			@Override
+			public String get()
+			{
+				fail("Should not be called.");
+				return null;
+			}
+		});
+
+		assertEquals(result, "foo");
+	}
+
+	@Test
+	public void orElseGetOfEmptyShouldGetFromSupplier()
+	{
+		Optional<String> given = Optional.empty();
+
+		String result = given.orElseGet(new Supplier<String>()
+		{
+			@Override
+			public String get()
+			{
+				return "foo";
+			}
+		});
+
+		assertEquals("foo", result);
+	}
 }