You're building a vending machine. It behaves differently when it has no money, has money, is dispensing, or is out of stock. Using if/else statements for every state creates complex,…
You're building a text editor with undo functionality. Users need to revert to previous document states, but exposing internal state would break encapsulation. The Memento pattern lets you save and…
You're building a dialog box with multiple UI components: buttons, text fields, checkboxes. When one component changes, others need to update. Without careful design, every component would need references to…
You're building a collection that stores data in a custom tree structure. You want to iterate over all elements, but exposing the internal structure would break encapsulation. The Iterator pattern…
You're building a text editor with undo/redo functionality. Every action (typing, deleting, formatting) needs to be reversible. How do you track what happened and how to undo it? The Command…
You're building a system that loads large images. Loading all images at startup would be slow and memory-intensive. You need images to load only when accessed, with caching to avoid…