我正在浏览 Google 的关于 Dialogs 的 Android 开发者页面，特别是本节。layout_newpayperiod.xml但是，我没有以编程方式创建 DialogFragment 的消息，而是使用以下元素命名了一个预设布局：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<Spinner
android:id="@+id/spinner_payperiod"
android:layout_width="fill_parent"
android:layout_height="48dp"
android:padding="8dp"
android:entries="@array/pay_periods"
/>
<EditText
android:id="@+id/edittext_savepercent"
android:layout_width="fill_parent"
android:layout_height="48dp"
android:padding="8dp"
android:inputType="number"
android:hint="Percent to Save"
/>
<EditText
android:id="@+id/edittext_payment"
android:layout_width="fill_parent"
android:layout_height="48dp"
android:padding="8dp"
android:inputType="numberDecimal"
android:hint="Total Payment"
/>
</LinearLayout>
当我调用 DialogFragment 时，它会正常显示，并且 Spinner 具有正确的值。我填写了条目并点击“确定”，但是当我尝试从 Spinner 和两个 EditText 字段中检索值时，应用程序会强制以NumberFormatException: Invalid double "". 我觉得我没有正确检索视图。任何人都可以帮我解决这个问题吗？谢谢！
public class StartPayperiodDialogFragment extends DialogFragment {
/* The activity that creates an instance of this dialog fragment must
* implement this interface in order to receive event callbacks.
* Each method passees the DialogFragment in case the host needs to query it.
*/
public interface StartPayperiodDialogListener{
public void onDialogPositiveClick(DialogFragment dialog);
public void onDialogNegativeClick(DialogFragment dialog);
}
// Use this instance of the interface to deliver action events
StartPayperiodDialogListener listener;
// Override the Fragment.onAttach() method to instantiate the StartPayperiodDialogListener
@Override
public void onAttach(Activity activity){
super.onAttach(activity);
// Verify that the host activity implements the callback interface
try{
// Instantiate the NoticeDialogListener so we can send events to the host
listener = (StartPayperiodDialogListener) activity;
}catch(ClassCastException e){
// The activity doesn't implement the interface, throw exception
throw new ClassCastException(activity.toString() + " must implement StartPayperiodDialogListener");
}
}
@Override
public Dialog onCreateDialog(Bundle savedInstanceState){
// Use the Builder class for convenient dialog construction
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
View transactionLayout = View.inflate(getActivity(), R.layout.layout_newpayperiod, null);
builder.setView(transactionLayout)
.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// Send the positive button event back to the calling activity
listener.onDialogPositiveClick(StartPayperiodDialogFragment.this);
}
})
.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// Send the negative button event back to the calling activity
listener.onDialogNegativeClick(StartPayperiodDialogFragment.this);
}
});
return builder.create();
}
}
在 MainActivity.class 中，回调方法：
@Override
public void onDialogPositiveClick(DialogFragment dialog) {
// User pressed OK, so we need to grab the values from the
// dialog's fields and apply them to the Views in the Main
// Activity
View transactionLayout = View.inflate(this, R.layout.layout_newpayperiod, null);
// Start with the payment amount
EditText paymentEt = (EditText) transactionLayout.findViewById(R.id.edittext_payment);
TextView paymentTv = (TextView) findViewById(R.id.text_paycheck);
paymentTv.setText(moneyFormat.format(Double.parseDouble(paymentEt.getText().toString())));
// Next, the percent to save
EditText savingsEt = (EditText) transactionLayout.findViewById(R.id.edittext_savepercent);
TextView savingsTv = (TextView) findViewById(R.id.text_savings);
savingsTv.setText(savingsEt.getText().toString() + "%");
// Then, the pay period
Spinner periodSp = (Spinner) transactionLayout.findViewById(R.id.spinner_payperiod);
TextView periodTv = (TextView) findViewById(R.id.text_payperiod);
periodTv.setText(periodSp.getSelectedItem().toString());
// Finally, let's update the daily allowance amount and clear
// the adapter
adapter.clear();
adapter.notifyDataSetChanged();
TextView allowanceTv = (TextView) findViewById(R.id.text_allowance);
Double allowanceValue;
switch(periodSp.getSelectedItemPosition()){
case(0): // Daily
allowanceValue = Double.parseDouble(paymentTv.getText().toString());
break;
case(1): // Weekly
allowanceValue = Double.parseDouble(paymentTv.getText().toString()) / 7;
break;
case(2): // 2 Weeks
allowanceValue = Double.parseDouble(paymentTv.getText().toString()) / 14;
break;
case(3): // 30 Days
allowanceValue = Double.parseDouble(paymentTv.getText().toString()) / 30;
break;
default: // Debugging purposes only
allowanceValue = 42.0;
break;
}
allowanceTv.setText(Double.toString(allowanceValue));
}