Android app development: fixing bugs before creating them

Solve common Android problems using a practical troubleshooting checklist and simple code examples to diagnose and fix issues before they derail development.

Understand how a java.lang.NullPointerException occurs when invoking a method on a null object due to mismatched activity xml. Fix by using the correct activity_main xml and adding missing resources.

Identify and fix runtime errors by declaring new activities in the manifest and ensuring all activities are orchestrated, preventing activity not found errors when navigating between screens.

Demonstrates how to diagnose and fix android activity not found errors when sending text via implicit intents, using chooser, package manager, and toast messages to ensure a valid target app.

This lecture explains a java.lang.ClassCastException when a button is cast to an image view, and fixes by changing button type to Button to prevent the crash and show a toast.

This lecture explains the android.os.NetworkOnMainThreadException and shows how network requests must run in a background thread to avoid crashing, including adding internet permission and moving requests to a background task.

Resolve Android security exceptions by declaring necessary internet permissions for network requests, noting some libraries require permissions while others do not, and running requests in a background thread.

Fix an illegal state exception by applying a Theme.AppCompat theme to the affected activity in the Android manifest, and verify manifest changes when debugging since logs may omit manifest details.

This lecture explains the android.view.ViewRootImpl$CalledFromWrongThreadException error and how to update the UI on the main thread while loading images in background threads.

Explore Kotlin uninitialized property access exception and fixes, including immediate primitive initialization, lazy for heavy objects, marking variables as knowable, and checking initialization before use.

Resolve error 10 by enabling cleartext http traffic in the Android manifest to allow an http request, noting that Android's default rules require https.

Avoid creating thousands of threads; use thread pools and IO schedulers to manage async tasks and prevent implicit overflow and stack overflow errors.

Explore how the Android application class onCreate runs before other activities, enabling library initialization. Fix error 12 by declaring a custom application in the manifest.

Diagnose a java.lang.NullPointerException by tracing a missing color field in a Java library used in an Android app, modify the data class and json handling, and verify the fix.

Diagnose an illegal state exception caused by vertical scrolling with infinite constraints in XML and compose, and outline solutions: remove scroll view, use a column, or cap the maximum constraint.

Explore common Android development bugs and practical solutions, and learn an approach to solve other issues across projects. Share feedback and stay tuned for next courses.