What problems can arise when implementing all functionality in a single Activity in Android?

Implementing all functionality in a single Activity leads to several problems:

• Maintainability and scalability issues: the code becomes bulky and hard to read, making it difficult to make changes and fix bugs.
• Lifecycle management problems: the Activity is responsible for many tasks, complicating proper management of states and resources.
• Poor modularity: it is difficult to reuse parts of the code because everything is tightly coupled within one class.
• Degradation of user experience: a large Activity may load slowly and cause interface lag.

It is better to divide functionality into multiple Activities or use fragments to organize UI and logic.