在alertDialog中对EditText进行验证

Question

我想在加空字段验证EditText上AlertDialog。但是即使字段为空，也不会显示错误消息，而是AlertDialog is closing. But if conditions are working well as I'm not able to do post operations if any of the field is empty.

这是我的Java示例代码：

public class TourActivity extends AppCompatActivity {

private LayoutInflater inflater;
private FloatingActionButton fab;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_tour);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    fab = (FloatingActionButton) findViewById(R.id.fab);

    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            inflater = TourActivity.this.getLayoutInflater();
            View content = inflater.inflate(R.layout.activity_add_new_trip, null);
            final EditText editEvent = (EditText) content.findViewById(R.id.edTxt_EventName);
            final EditText editStartDate = (EditText) content.findViewById(R.id.edTxt_EventSDate);


            AlertDialog.Builder builder = new AlertDialog.Builder(TourActivity.this);
            builder.setView(content)
                    .setTitle("Add Event")
                    .setPositiveButton(android.R.string.ok,
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {

                                    editEvent.setError(null);
                                    editStartDate.setError(null);

                                    boolean cancel = false;
                                    View focusView = null;

                                    if (TextUtils.isEmpty(editEvent.getText().toString()))) {
                                        editEvent.setError("Please Enter Event Name.");
                                        return;
                                    }

                                    if (TextUtils.isEmpty(editStartDate.getText().toString())) {
                                        editStartDate.setError("Please Enter Event Start Date.");
                                        focusView = editStartDate;
                                        cancel = true;
                                    }


                                    if (cancel == true) {
                                        Snackbar.make(findViewById(android.R.id.content),
                                                "Event Unsuccessful.", Snackbar.LENGTH_LONG)
                                                .setActionTextColor(Color.RED)
                                                .show();
                                        focusView.requestFocus();
                                    } else {
                                        // Some action here
                                    }
                                }
                            })
                    .setNegativeButton(cancel, new DialogInterface.OnClickListener() {

                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.dismiss();
                        }
                    });
            AlertDialog dialog = builder.create();
            dialog.show();
        }
    });
}
}

Answer 1

This answer is compiled from Android Dialog, keep dialog open when button is pressed.

As written in Dismissing Dialog API Guide,

When the user touches any of the action buttons created with an AlertDialog.Builder, the system dismisses the dialog for you.

So you need to make a custom click listener for prevent the dialog being closed.

First Way
You can prevent the positive button from closing the dialog. You basically need to:

1. Create the dialog with DialogBuilder
2. show() the dialog
3. Find the buttons in the dialog shown and override their onClickListener

So, create a listener class:

class CustomListener implements View.OnClickListener {
  private final Dialog dialog;

  public CustomListener(Dialog dialog) {
    this.dialog = dialog;
  }

  @Override
  public void onClick(View v) {
    // Do whatever you want here

    // If you want to close the dialog, uncomment the line below
    //dialog.dismiss();
  }
}

Then when showing the dialog use:

AlertDialog dialog = dialogBuilder.create();
dialog.show();
Button theButton = dialog.getButton(DialogInterface.BUTTON_POSITIVE);
theButton.setOnClickListener(new CustomListener(dialog));

Remember, you need to show the dialog otherwise the button will not be findable. Also, be sure to change DialogInterface.BUTTON_POSITIVE to whatever value you used to add the button. Also note that when adding the buttons in the DialogBuilder you will need to provide onClickListeners - you can not add the custom listener in there, though - the dialog will still dismiss if you do not override the listeners after show() is called.

Second Way

这是使用匿名类的相同方法的示例，因此全部包含在一个代码流中：

AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setMessage("Test for preventing dialog close");
AlertDialog dialog = builder.create();
dialog.show();

//Overriding the handler immediately after show is probably a better approach than OnShowListener as described below
dialog.getButton(AlertDialog.BUTTON_POSITIVE).setOnClickListener(new View.OnClickListener() {            
     @Override
     public void onClick(View v) {
       boolean wantToCloseDialog = false;

       //Do stuff, possibly set wantToCloseDialog to true then...
       if(wantToCloseDialog)
          dismiss();
       //else dialog stays open. Make sure you have an obvious way to close the dialog especially if you set cancellable to false.
       }
    });

Answer 2

尝试这样：

if (TextUtils.isEmpty(edEvent)) {
    editEvent.setError("Please Enter Event Name.");
    editEvent.requestFocus();
    return;
}