Streams Exercises

The goal of the exercises is to help you review basic Stream operations like map, filter, flatMap, and collect.

Solutions are available in src/main/java/solutions/basics/streams/StreamExercises.java

Exercises

The exercise is to fix the code in src/main/java/exercises/basics/streams/StreamExercises.java to enable the tests to pass.

1. Remove the @Ignore annotation from the test in src/test/java/exercises/basics/streams/StreamTest.java this will enable three failing unit tests
2. The toUpperCase method is relatively simple to fix with a map and Collectors.toList(). This will resolve one unit test
3. Fix the calculateOrderSummary method this way:
   • Create a method private String getProductDetail(Order order) that returns a string like “1 Baseball and 1 glove” for the order. This is accomplished with map and the Collectors.joining collector
   • Create a method private String toOrderSummary(Order order) that returns a string like “Fred ordered 1 Baseball and 1 glove” for the order. This is simple string concatenation using the above method
   • Finally, complete the public String calculateOrderSummary(List<Order> orders) method with a map using the method above and the Collectors.joining collector. This method returns a string for every order, joined with the newline character. This will resolve one more unit test.
4. The public int calculateTotalOrdered(List<Order> orders, String productName) method can be completed with one chained pipeline including flatMap, filter, mapToInt, and sum. See the example in the code for an understanding of how mapToInt works.