Nested Structures
Explore the concept of nested data structures in Java, such as combining HashMaps and ArrayLists, to build practical applications like weekly meal and study planners. Understand how to organize, calculate, and summarize data across multiple levels, enhancing your ability to manage complex datasets in coding projects.
The project
You’ve been tracking calories by day and meal type, but now you want to see the whole week’s nutrition in one system. Instead of running your tracker day by day, you need a planner that stores all 7 days of meals, calculates per-meal totals, and shows both daily summaries and a weekly summary.
Type the following:
Day 1 Breakfast: 400Day 1 Lunch: 600Day 1 Dinner: 300
It is useful, but it doesn’t give you a complete weekly overview. What you need is a nested structure, a way to combine HashMap and ArrayList so data is organized by day and meal category.
We’ll build a Weekly Meal Planner that organizes meals by day (keys), meal type (sub-keys), and calories (lists). Then, we’ll calculate per-meal totals, daily totals, and the final weekly total.
The programming concept
The programming concept for today is nested structures.
A nested ...