Android Programming - Changing Button Text Programmatically with Alert Dialog

Question

I'm trying to create an app for editing guitar tabs. I have an array of buttons that represent the frets and I want to be able to click on the button to open an alert dialog to set the text of that button to be the number that's input.

The editFret function below is called by the button through its onClick property. When I run this, I can press on a button and it brings up the dialog and I can input the number fine. After pressing OK on the dialog though, the button just becomes blank. When I click on the button again, or any other button, the number then shows up as the text in the button. It also keeps changing the text in any buttons clicked afterwards to whatever the last input value was.

I tried changing the button text to a constant value on a click and didn't have any problems so I'm assuming the problem is with the getFret function although I can't possibly see what it would be as it's just fetching a string.

//Create string to store the fret number
String fret;

public void getFret(){
    //Create text input field
    final EditText input = new EditText(this);
    input.setInputType(InputType.TYPE_CLASS_NUMBER);
    input.setFilters(new InputFilter[] {new InputFilter.LengthFilter(2)});

    new AlertDialog.Builder(this)
            .setTitle("Edit fret")
            .setMessage("Input fret number")
            .setView(input)
            .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    fret = input.getText().toString();
                }
            })
            .setNegativeButton("Cancel",new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    //Do nothing
                }
            }).show();
}

public void editFret(View view){
    Button button = (Button) view;
    getFret();
    button.setText(fret);
    button.invalidate();  //Don't know if this is necessary
}

Answer 1

You need to change your setPositiveButton to:

.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    fret = input.getText().toString();
                    button.setText(fret);
                }
            })

and change Button to global variable instead of local one.

The problem here is when you are calling editFret(View view) it will also call getFret() that will show the dialog and then call button.setText(fret) without waiting for the user to press OK or Cancel so you need to set the text when the OnClickListener is called.

Answer 2

You should set value when user clicks OK in AlertDialog . Here it is how

new AlertDialog.Builder(this)
            .setTitle("Edit fret")
            .setMessage("Input fret number")
            .setView(input)
            .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    fret = input.getText().toString();
                    //TODO: HERE SET THE BUTTON VIEW AND TEXT TO IT
                    Button button = (Button) findViewById(R.id.button); // This line
                    button.setText(fret); // And this line
                }
            })
            .setNegativeButton("Cancel",new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    //Do nothing
                }
            }).show();

It will set the text when AlertDialog 's OK will be clicked!

Maybe setting text in your method is redundant approach. You should better use this method just to call AlertDialog

public void editFret(View view){
    //Button button = (Button) view;
    getFret();
    //button.setText(fret);
    //button.invalidate();  //Don't know if this is necessary
}

Hope it works or let me know, Cheers