Null Validation on EditText box in Alert Dialog - Android

I am trying to add some text validation to an edit text field located within an alert dialog box. It prompts a us开发者_Python百科er to enter in a name.

I want to add some validation so that if what they have entered is blank or null, it does not do anything apart from creating a Toast saying error.

So far I have:

    AlertDialog.Builder alert = new AlertDialog.Builder(this);
    alert.setTitle("Record New Track");
    alert.setMessage("Please Name Your Track:");
    // Set an EditText view to get user input
    final EditText trackName = new EditText(this);
    alert.setView(trackName);
    alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {

            String textString = trackName.getText().toString(); // Converts the value of getText to a string.
            if (textString != null && textString.trim().length() ==0)
            {   

                Context context = getApplicationContext();
                CharSequence error = "Please enter a track name" + textString;
                int duration = Toast.LENGTH_LONG;

                Toast toast = Toast.makeText(context, error, duration);
                toast.show();


            }
            else 
            {

                SQLiteDatabase db = waypoints.getWritableDatabase();
                ContentValues trackvalues = new ContentValues();
                trackvalues.put(TRACK_NAME, textString);
                trackvalues.put(TRACK_START_TIME,tracktimeidentifier );
                insertid=db.insertOrThrow(TRACK_TABLE_NAME, null, trackvalues);

            }

But this just closes the Alert Dialog and then displays the Toast. I want the Alert Dialog to still be on the screen.

Thanks

I think you should recreate the Dialog, as it seems the DialogInterface given as a parameter in onClick() doesn't give you an option to stop the closure of the Dialog.

I also have a couple of tips for you:

Try using Activity.onCreateDialog(), Activity.onPrepareDialog() and of course Activity.showDialog(). They make dialog usage much easier (atleast for me), also dialog usage looks more like menu usage. Using these methods, you will also be able to more easilty show the dialog again.

I want to give you a tip. It's not an answer to your question, but doing this in an answer is much more readable.

Instead of holding a reference to an AlertDialog.Builder() object, you can simply do:

new AlertDialog.Builder(this)
.setTitle("Record New Track")
.setMessage("Please Name Your Track:")
//and some more method calls
.create();
//or .show();

Saves you a reference and a lot of typing ;). (almost?) All methods of AlertDialog.Builder return an AlertDialog.Builder object, which you can directly call a method on.

The same goes for Toasts:

Toast.makeText(this, "Please enter...", Toast.LENGTH_LONG).show();

I make a new method inside my class that shows the alert and put all the code for creating the alert in that one method. then after calling the Toast I call that method. Say I named that method createAlert(), then I have,

  createAlert(){

 AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.setTitle("Record New Track");
alert.setMessage("Please Name Your Track:");
// Set an EditText view to get user input
final EditText trackName = new EditText(this);
alert.setView(trackName);
alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialog, int whichButton) {

        String textString = trackName.getText().toString(); // Converts the value of getText to a string.
        if (textString != null && textString.trim().length() ==0)
        {   

            Context context = getApplicationContext();
            CharSequence error = "Please enter a track name" + textString;
            int duration = Toast.LENGTH_LONG;

            Toast toast = Toast.makeText(context, error, duration);
            toast.show();
            createAlert();



        }
        else 
        {

            SQLiteDatabase db = waypoints.getWritableDatabase();
            ContentValues trackvalues = new ContentValues();
            trackvalues.put(TRACK_NAME, textString);
            trackvalues.put(TRACK_START_TIME,tracktimeidentifier );
            insertid=db.insertOrThrow(TRACK_TABLE_NAME, null, trackvalues);

        }
}

What you should do is to create a custom xml layout including a textbox and an Ok button instead of using .setPositiveButton. Then you can add a click listener to your button in order to validate the data and dismiss the dialog.

It should be used in CreateDialog:

protected Dialog onCreateDialog(int id) 
{
            LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);

if (id==EDIT_DIALOG)
{
            final View layout = inflater.inflate(R.layout.edit_dialog, (ViewGroup) findViewById(R.id.Layout_Edit));

            final Button okButton=(Button) layout.findViewById(R.id.Button_OkTrack);
            final EditText name=(EditText) layout.findViewById(R.id.EditText_Name);
            okButton.setOnClickListener(new View.OnClickListener() 
            {
                public void onClick(View v) {
                    String textString = trackName.getText().toString(); 
                    if (textString != null && textString.trim().length() ==0)
                    {
                        Toast.makeText(getApplicationContext(), "Please enter...", Toast.LENGTH_LONG).show();
                    } else
                        removeDialog(DIALOG_EDITTRACK);
                }
            });            
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setView(layout);
            builder.setTitle("Edit text");

            AlertDialog submitDialog = builder.create();            
            return submitDialog;
}

Even though it's an old post, the code below will help somebody. I used a customized layout and extended DialogFragment class.

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {

    // Get the layout inflater
    LayoutInflater inflater = requireActivity().getLayoutInflater();

    final View view = inflater.inflate(R.layout.Name_of_the_customized_layout, null);

    final EditText etxtChamp = view.findViewById(R.id.editText);


    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setMessage("Enter a Name")
            .setTitle("Mandatory field ex.");

    builder.setView(view);

    final Button btnOk = view.findViewById(R.id.ok);
    final Button btnCancel = view.findViewById(R.id.cancel);

    btnOk.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if(etxtChamp.getText().toString().isEmpty()){
                etxtChamp.setError("Oups! ce champ est obligatoire!");
            }else{
                //Get the editText content and do whatever you want
                String messageEditText = etxtChamp.getText().toString();

                dismiss();
            }
        }
    });

    btnCancel.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            dismiss();
        }
    });

    return builder.create();
}

Use This code for displaying Dialog.

 public void onClick(DialogInterface dialog, int whichButton) {

            String textSt`enter code here`ring = trackName.getText().toString(); // Converts the value of getText to a string.
            if (textString != null && textString.trim().length() ==0)
            {       
                Context context = getApplicationContext();
                CharSequence error = "Please enter a track name" + textString;
                int duration = Toast.LENGTH_LONG;

                Toast toast = Toast.makeText(context, error, duration);
                toast.show();

                new AlertDialog.Builder(this)
                .setTitle("Message")
                .setMessage("please enter valid field")
                .setPositiveButton("OK", null).show();            
            }

This will create a Dialog for you, editText is empty or what are conditions you wants.

//if view is not instantiated,it always returns null for edittext values.

View v = inflater.inflate(R.layout.new_location_dialog, null);
builder.setView(v); 



final EditText titleBox = (EditText)v.findViewById(R.id.title);
final EditText descriptionBox = (EditText)v.findViewById(R.id.description);