android - 在 alertDialog 中验证 EditText

Question

我正在尝试在 AlertDialog 上的 EditText 上添加空字段验证。但即使字段为空，也不会显示错误消息，而是关闭 AlertDialog。但是，如果条件运行良好，因为如果任何字段为空，我将无法进行后期操作。

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

此答案编译自Android Dialog, keep dialog open when button is pressed .

写在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.

所以你需要制作一个自定义的点击监听器来防止对话框被关闭。

First Way
您可以防止肯定按钮关闭对话框。您基本上需要:

1. 使用 DialogBu​​ilder 创建对话框
2. 显示() 对话框
3. 在显示的对话框中找到按钮并覆盖它们的 onClickListener

因此，创建一个监听器类:

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();
  }
}

然后在显示对话框时使用:

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

请记住，您需要显示对话框，否则将找不到按钮。此外，请务必将 DialogInterface.BUTTON_POSITIVE 更改为您用于添加按钮的任何值。另请注意，在 DialogBu​​ilder 中添加按钮时，您需要提供 onClickListeners - 但您不能在其中添加自定义监听器 - 如果您仍然关闭对话框调用 show() 后不要覆盖监听器。

Second Way

下面是一个使用匿名类的相同方法的示例，因此它全部在一个代码流中:

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.
       }
    });