dogriffiths / headfirstandroid3rded

Hello 👋

I've been writing software since I was about 12 years old, but to be frank, some of the code from those early days wasn't very good, and you've probably never used it.

Since then, I have gone through puberty. That was quite traumatic, so I'll draw a veil over the details. Then came university and a variety of jobs that mostly involved typing.

I've written a few books, including ones on Android development and React web development.

I also give courses on the O'Reilly Media learning platform, and I present a video course called Business Writing Essentials that will show you in 90 minutes how to go from no ideas, and a blank page, to a fully finished piece of writing.

Aside from that, I'm the founder of a company that produces a cloud-based version of the old clocking-in and clocking-out machines, and provides development consultancy for Android and front-end web development.

I'm reasonably approachable unless it's before I've had coffee.

Training Things

• My courses and videos at O'Reilly Media

Books

• React Cookbook
• Head First Android Development
• Head First Kotlin
• 97 Things Every Java Programmer Should Know
• Head First C
• Head First Programming

Social Media

headfirstandroid3rded's Issues

Type mismatch: inferred type is TaskItemAdapter but TaskItemAdapter.TaskItemViewHolder was expected

In chapter 15 TaskItemAdapter.kt
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) : TaskItemViewHolder = TaskItemViewHolder.inflateFrom(parent)
android studio gives error :
Type mismatch: inferred type is TaskItemAdapter but TaskItemAdapter.TaskItemViewHolder was expected.
Is there anything wrong?
Thank you!

Companion object for bundle keys

In the stopwach example shouldn't you use a companion object for the bundle keys (so they are static) instead of making them instance variables?

class MainActivity : AppCompatActivity() {
    companion object {
        val RUNNING_KEY = "RUNNING"
        val OFFSET_KEY = "OFFSET"
        val BASE_KEY = "BASE"
    }

    lateinit var stopwatch: Chronometer
    var running = false
    var offset: Long = 0L

    override fun onSaveInstanceState(outState: Bundle) {
        outState.putBoolean(RUNNING_KEY, running)
        outState.putLong(OFFSET_KEY, offset)
        outState.putLong(BASE_KEY, stopwatch.base)
        super.onSaveInstanceState(outState)
    }
   ...