在 Android 11 中，为什么返回按钮和向后滑动手势在我的代码中表现不同？

Question

Android 11.

I have an activity that has a back button on the top toolbar. It's set up on a Base activity with this code:

fun setupToolbar(toolbarId: Int, title: String = "") 
{
    val toolbar: Toolbar = findViewById(toolbarId)
    setSupportActionBar(toolbar)

    supportActionBar?.apply {
        setDisplayShowTitleEnabled(false)
        setDisplayHomeAsUpEnabled(true)
        val textView = findViewById<TextView>(R.id.tb_global_title)
        textView.text = title
    }
}

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    // handle arrow click here
    if (item.itemId == android.R.id.home) {
       onBackPressed() // Call onBackPressed in the current activity
    }
    return super.onOptionsItemSelected(item)
}

And this is how I set up the toolbar with that back button on any activity:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_image_select)
    setupToolbar(R.id.tb_image_select, getString(R.string.toolbar_image_select))
    // do stuff
}

When the back button OR the back swipe gesture is completed on my activity, the following code gets called:

override fun onBackPressed() {
    // do stuff
    setResult(Activity.RESULT_OK)
    super.onBackPressed()
}

What I'm expecting is this code to get called and go into the RESULT_OK step:

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    if (resultCode == Activity.RESULT_OK) {
        rv_select_image.adapter!!.notifyDataSetChanged()
    }
}

The problem is that the code only goes into RESULT_OK (-1) on the swipe gesture, but not the back button (0).

Anyone know why this could be?

Answer 1

I figured it out. It was simply an overlook on my part. Within the activity I was doing an additional override here when any selection was done on a toolbar:

override fun onOptionsItemSelected(item: MenuItem): Boolean {
   // do stuff
   finish()

   return super.onOptionsItemSelected(item)
}

The finish() caused the result to be set to 0 after it was set previsouly to -1 in onBackPressed() . Simply adding an if statement to check that the button pressed wasn't the back button was enough to fix the issue for me:

override fun onOptionsItemSelected(item: MenuItem): Boolean {
   // do stuff
   if (item.itemId != android.R.id.home) {
       finish()
   }

   return super.onOptionsItemSelected(item)
}