配置更改时 TextInputLayout 的错误

Question

我在应用程序中使用TextInputLayout，当我向TextWatcher添加时，TextInputEditText在TextInputLayout上设置了error，当我触发配置更改时，我的应用程序崩溃了。

editText.addTextChangedListener(object : TextWatcher {
override fun afterTextChanged(text: Editable) {
// no-op
}
override fun beforeTextChanged(text: CharSequence, start: Int, count: Int, after: Int) {
// no-op
}
override fun onTextChanged(text: CharSequence, start: Int, before: Int, count: Int) {
textInputLayout.error = if (text.isBlank()) {
getString(R.string.error_text)
} else {
null
}
}
})

堆栈跟踪是

java.lang.NullPointerException：尝试从字段 'int 读取 android.view.View.mViewFlags' on a null 对象引用 at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java：3863( at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java：3864( at com.google.android.material.textfield.TextInputLayout.dispatchRestoreInstanceState(TextInputLayout.java：2053( at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java：3864( at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java：3864( at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java：3864( at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java：3864( at android.view.View.restoreHierarchyState(View.java：19808( at androidx.fragment.app.Fragment.restoreViewState(Fragment.java：539( at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java：907( at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectState(FragmentManagerImpl.java：1238( at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java：1303( at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java：2656( at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java：2610( at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java：246( at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java：542( at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java：201( at android.app.Instrumentation.callActivityOnStart(Instrumentation.java：1425( at android.app.Activity.performStart(Activity.java：7825( at android.app.ActivityThread.handleStartActivity(ActivityThread.java：3294( at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java：221( at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java：201( at android.app.servertransaction.TransactionExecutor.executeLifecycle State(TransactionExecutor.java：173( at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java：97( at android.app.ActivityThread$H.handleMessage(ActivityThread.java：2016( at android.os.Handler.dispatchMessage(Handler.java：107( at android.os.Looper.loop(Looper.java：214( at android.app.ActivityThread.main(ActivityThread.java：7356( at java.lang.reflect.Method.invoke(Native Method( at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java：492( at com.android.internal.os.ZygoteInit.main(ZygoteInit.java：930(

Answer 1

似乎您可能需要覆盖onViewStateRestored并从那里删除/添加TextWatcher。

您还应该将TextWatcher保存在可以在配置更改(例如 AndroidViewModel(中幸存下来

的地方。下面是一个快速示例：

// Inside of onViewStateRestored
if (viewModel.textWatcher != null) {
editText.removeTextChangedListener(viewModel.textWatcher)
viewModel.textWatcher = null
}
// Create and add TextWatcher back