Java8 Lambda - Stream INSTA

Get Started with lambda and stream. New astonishing features of Java 8. It's inspired by java 8 kata.

Usage

• Run the tests

You can run tests from your IDE or command line if you like. If you are using an IDE, right click on the test method and click Run foobar(). If you prefer command line, follow below.

$ pwd
/path/to/java8-code-kata

$ ./mvnw install -Dmaven.test.skip=true

$ ./mvnw test -Dtest=Exercise1Test#findRichCustomers -pl stream-api

• Edit unit tests.

To successfully pass the tests, you'll need to edit the test itself. You can see where you need to edit.

@Easy @Test
public void simpleAddition() {
    /**
     * Get an addition result of 1 and 2 by using an operator "+".
     */
    Integer added = null;

    assertThat(added, is(3));
}

Here is a sample answer.

@Easy @Test
public void simpleAddition() {
    /**
     * Get an addition result of 1 and 2 by using an operator "+".
     */
    Integer added = 1 + 2;

    assertThat(added, is(3));
}

Most tests are annotated with @Easy which means those tests only requires basic knowledge.

Tests annotated with @Difficult are more difficult. 😁

Modules

Playground

Use in conference session only

stream-api

• Exercise1Test.java

Stream#filter and Stream#map

• Exercise2Test.java

Stream#sorted, Stream#distinct, Stream#limit and Stream#flatMap

• Exercise3Test.java

Stream#count, Stream#max and Stream#min

• Exercise4Test.java

Stream#findFirst, Stream#allMatch, Stream#anyMatch and Stream#noneMatch

• Exercise5Test.java

Stream#collect and Collectors

• Exercise6Test.java

Stream#of and Stream#iterate

• Exercise7Test.java

IntStream, LongStream and DoubleStream

• Exercise8Test.java

Advanced problems

• Exercise9Test.java

Collector

collection-interfaces

• Exercise1Test.java

Iterable#forEach, Collection#removeIf, List#replaceAll, List#sort, Collection#stream and Collection#parallelStream

• Exercise2Test.java

Map#getOrDefault, Map#putIfAbsent, Map#merge and Map#computeIfPresent