Зміст курсу

Stream API

1. Fundamentals and Functional Capabilities of Stream API

Architecture Principles What Is a Functional Interface?Predicate: Data Filtering Challenge: Filtering Corporate Email Addresses Function: Data Transformation Challenge: Income Tax Calculation Comparable: Natural Ordering of Data Comparator: Custom Comparison of Data Challenge: Sorting Employees Consumer: Processing Data Supplier: Data Generation Bi-versions of Functional Interfaces Challenge: Filtering Users by Two Criteria BinaryOperator: Combining Two Values

2. Intermediate Operations in Stream API

Transforming Elements with the map() Method Filtering Elements with the filter() Method Challenge: Factory Product Filtering Working with Nested Structures with the flatMap() Method Arranging Items in Order with the sorted() Method Challenge: Selecting the Best Cars on the Production Line Eliminating Duplicates with the distinct() Method Challenge: Factory Quality Control Restricting and Skipping Elements with the limit() and skip() Methods Challenge: Finding the Top 3 Hardest-Working Employees Intermediate Processing with the peek() Method

3. Terminal Operations in the Stream API

collect() Gathering Stream Elements into a Collection Challenge: Build a Custom Collector for Category Counting Collectors Utility Class for Stream API Processing Elements with the forEach() Method Handling Values with the Optional Class Aggregating Elements with the reduce() Method Challenge: Calculating Total Cost with Discounts and Tax Calculating Stream Statistics with count(), max(), and min()Retrieving Stream Summary Metrics with summaryStatistics() Method Retrieving Elements from a Stream with findFirst() and findAny()Challenge: Selecting Random Products Within a Category Checking Stream Elements Against a Condition with allMatch()Challenge: Ensuring Fast Delivery for Expensive Products

4. Practical Applications of Stream API

Real-World Examples of Using Stream API Performance in Stream API Exception Handling in Stream API Summary

Challenge: Calculating Total Cost with Discounts and Tax

Завдання

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Implement a shopping cart system that calculates the total order cost, applying a discount and sales tax based on predefined conditions.

Use map() to get the total price of each product (there is a dedicated method getTotalPrice() in the Product class).
Apply reduce() to sum up all product prices.
Use a ternary operator to check if the subtotal exceeds the discount threshold (DISCOUNT_THRESHOLD) and calculate the discount. If subtotal is greater than the threshold, apply a 10% discount (DISCOUNT_PERCENTAGE); otherwise, set the discount to 0.0.
Determine the discount amount by multiplying subtotal by DISCOUNT_PERCENTAGE.
Calculate the pre-tax amount (preTaxAmount) by subtracting discount from subtotal.
Compute the sales tax (tax) by multiplying preTaxAmount by the sales tax rate (SALES_TAX).
Return the final total, calculated as preTaxAmount + tax.

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