Kursinhalt
Stream API
Stream API
1. Fundamentals and Functional Capabilities of Stream API
ArchitecturePrinciplesWhat Is a Functional Interface?Predicate: Data FilteringChallenge: Filtering Corporate Email AddressesFunction: Data TransformationChallenge: Income Tax CalculationComparable: Natural Ordering of DataComparator: Custom Comparison of DataChallenge: Sorting Employees Consumer: Processing Data Supplier: Data GenerationBi-versions of Functional InterfacesChallenge: Filtering Users by Two CriteriaBinaryOperator: Combining Two Values
2. Intermediate Operations in Stream API
Transforming Elements with the map() MethodFiltering Elements with the filter() MethodChallenge: Factory Product FilteringWorking with Nested Structures with the flatMap() MethodArranging Items in Order with the sorted() MethodChallenge: Selecting the Best Cars on the Production LineEliminating Duplicates with the distinct() MethodChallenge: Factory Quality ControlRestricting and Skipping Elements with the limit() and skip() MethodsChallenge: Finding the Top 3 Hardest-Working EmployeesIntermediate Processing with the peek() Method
3. Terminal Operations in the Stream API
collect() Gathering Stream Elements into a CollectionChallenge: Build a Custom Collector for Category CountingCollectors Utility Class for Stream APIProcessing Elements with the forEach() MethodHandling Values with the Optional ClassAggregating Elements with the reduce() MethodChallenge: Calculating Total Cost with Discounts and TaxCalculating Stream Statistics with count(), max(), and min()Retrieving Stream Summary Metrics with summaryStatistics() MethodRetrieving Elements from a Stream with findFirst() and findAny()Challenge: Selecting Random Products Within a CategoryChecking Stream Elements Against a Condition with allMatch()Challenge: Ensuring Fast Delivery for Expensive Products
4. Practical Applications of Stream API
Challenge: Build a Custom Collector for Category Counting
Aufgabe
Swipe to start coding
You need to implement a custom Collector that processes a list of products and counts how many products belong to each category.
- In the
supplier()method, return a newHashMap. - In the
accumulator()method, call theget()method on theproductmap to retrieve the value of the"category"key and pass it as the first parameter of themerge()method. - For the second parameter in the same method, provide the initial value (
1). - In the
combiner()method, pass thekeyofmap2as the first parameter of themerge()method. - For the second parameter in the same method, pass the
valueof themap2. - In the
finisher()method, return themapwithout modifying it using a lambda. - In the
characteristics()method, return a set that ensures the collection remains unchanged (IDENTITY_FINISH). - In the
collect()method, pass the implementation of theCollectorinterface (CategoryCountCollector).
Lösung
solution
Wechseln Sie zum Desktop, um in der realen Welt zu übenFahren Sie dort fort, wo Sie sind, indem Sie eine der folgenden Optionen verwendenWar alles klar?
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Abschnitt 3. Kapitel 2
Challenge: Build a Custom Collector for Category Counting
Aufgabe
Swipe to start coding
You need to implement a custom Collector that processes a list of products and counts how many products belong to each category.
- In the
supplier()method, return a newHashMap. - In the
accumulator()method, call theget()method on theproductmap to retrieve the value of the"category"key and pass it as the first parameter of themerge()method. - For the second parameter in the same method, provide the initial value (
1). - In the
combiner()method, pass thekeyofmap2as the first parameter of themerge()method. - For the second parameter in the same method, pass the
valueof themap2. - In the
finisher()method, return themapwithout modifying it using a lambda. - In the
characteristics()method, return a set that ensures the collection remains unchanged (IDENTITY_FINISH). - In the
collect()method, pass the implementation of theCollectorinterface (CategoryCountCollector).
Lösung
solution
Wechseln Sie zum Desktop, um in der realen Welt zu übenFahren Sie dort fort, wo Sie sind, indem Sie eine der folgenden Optionen verwendenWar alles klar?
Danke für Ihr Feedback!
Abschnitt 3. Kapitel 2
Wechseln Sie zum Desktop, um in der realen Welt zu übenFahren Sie dort fort, wo Sie sind, indem Sie eine der folgenden Optionen verwenden