java - 方向更改崩溃后替换 fragment

Question

当用户改变屏幕方向并执行“goToDetails”时，FragmentManager 抛出

java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState

类代码:

@ActivityScope
class NavigatorImpl @Inject constructor(): ActivityLifecycleTask(), Navigator {

private lateinit var fragmentManager: FragmentManager

@IdRes
private var fragmentContainerRes: Int = 0

override fun onCreate(activity: BaseActivity) {
    fragmentManager = activity.supportFragmentManager
    fragmentContainerRes = activity.fragmentContainerRes()
}

override fun init(fragment: BaseFragment) {
    goToFragment(fragment, TAG_INIT_FRAGMENT)
}

override fun goToDetails(id: Long) {
    goToFragment(DetailsFragment.create(id))
}

private fun goToFragment(fragment: Fragment, tag: String? = null) {
    Log.d(javaClass.simpleName, "goToFragment")
    fragmentManager.beginTransaction()
            .add(fragmentContainerRes, fragment, tag)
            .addToBackStack(null)
            .commit()
}

companion object {
    private const val TAG_INIT_FRAGMENT = "TAG_INIT_FRAGMENT"
}
}

commitAllowingInstanceStateLoss() 不工作。 onCreate(activity) 在 Activity onCreate 回调中执行。然后当 savedInstanceState == null 时，执行来自 NavigatorImpl 的 init()。

Answer 1

当您旋转屏幕时，您的 Activity 的 onCreate 将执行，但它的 savedInstanceState 不会为 null。如果您不检查它是否为空，您仍然会尝试提交一个新事务来初始化您的 Activity 。所以你应该在初始化你的 fragment 之前检查是否 savedInstanceState == null。

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (savedInstanceState == null) {
        // commit your fragment transaction.
    }
}