android - 底部导航 setOnItemSelectedListener 返回 super

Question

我的 botton navation 设置如下，它工作正常。

navController = findNavController(R.id.nav_host_fragment)
appBarConfiguration = AppBarConfiguration(setOf(R.id.nav_1, R.id.nav_2))
setupActionBarWithNavController(navController, appBarConfiguration)
binding.bottomNavView.setupWithNavController(navController)

现在，如果当前 fragment 是第二个 fragment 并且其中设置了一些标志，我想防止切换 fragment 。
我试过使用 bottomNavView.setOnItemSelectedListener但它破坏了整个导航 Controller 机制，需要自己进行 fragment 和标题切换。
是否有任何其他方法可以覆盖特定项目的导航 Controller 行为，并让它像往常一样处理其余部分，例如 super.onItemSelected() ?

Answer 1

根据 the setupWithNavController() documentation :

This will call onNavDestinationSelected when a menu item is selected.

因此，如果您想从自己的监听器中执行默认行为，您可以简单地调用该方法。

// Call setupWithNavController to get the automatic
// selection of the correct bottom nav item
// based on the NavController's state
binding.bottomNavView.setupWithNavController(navController)
// Then override the OnItemSelectedListener
// with your own with your custom logic
binding.bottomNavView.setOnItemSelectedListener { item ->
    if (navController.currentDestination?.id == R.id.fragment_id && !yourConditionIsMet) {
        // Return false to not allow navigating to the tab
        false
    } else {
        // Do the default behavior
        onNavDestinationSelected(
            item,
            navController
        )
    }
}