align AlertDialog buttons to center

Question

I use this codes for Android (Java) programming:

public static MessageBoxResult showOk(
        Context context, String title, String message, String okMessage)
{
    okDialogResult = MessageBoxResult.Closed;

    // make a handler that throws a runtime exception when a message is received
    final Handler handler = new Handler()
    {
        @Override
        public void handleMessage(Message mesg)
        {
            throw new RuntimeException();
        }
    };

    AlertDialog.Builder alert = new AlertDialog.Builder(context);
    alert.setTitle(title);
    alert.setMessage(message);

    alert.setPositiveButton(okMessage, new DialogInterface.OnClickListener() {

        public void onClick(DialogInterface dialog, int whichButton) {
            okDialogResult = MessageBoxResult.Positive;
            handler.sendMessage(handler.obtainMessage());
        }
    });

    AlertDialog dialog = alert.show();


    // align button to center
    Button b = (Button) dialog.findViewById(android.R.id.button1);
    b.setGravity(Gravity.CENTER_HORIZONTAL);

    // loop till a runtime exception is triggered.
    try { Looper.loop(); }
    catch(RuntimeException e2) {}

    return okDialogResult;
}

My problem is how make center the button? As you see I try to align button to cnenter using Gravity.CENTER_HORIZONTAL (also .CENTER) but nothing changes. The button is almost in right position.

Solution 1

This worked for me :

    final AlertDialog.Builder builder = new AlertDialog.Builder(getActivity(), R.style.AppCompatAlertDialogStyle);
    builder.setCancelable(true);
    builder.setTitle(title);
    builder.setMessage(message);

    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {

        }
    });


    final AlertDialog dialog = builder.create();
    dialog.show(); //show() should be called before dialog.getButton().


    final Button positiveButton = dialog.getButton(AlertDialog.BUTTON_POSITIVE);
    LinearLayout.LayoutParams positiveButtonLL = (LinearLayout.LayoutParams) positiveButton.getLayoutParams();
    positiveButtonLL.gravity = Gravity.CENTER;
    positiveButton.setLayoutParams(positiveButtonLL);

Solution 2

Use crtn's method, but instead of changing the LayoutParam's gravity, change its width to ViewGroup.LayoutParams.MATCH_PARENT;

Solution 3

If you want to have Positive And Negative Buttons at the same time (Large & Center), you can use something like this:

AlertDialog alertDialog = new AlertDialog.Builder(this).create();
alertDialog.setTitle("Title");
alertDialog.setMessage("Message");

alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "Yes",
        new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });

alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "No",
        new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                 dialog.dismiss();
            }
         });
alertDialog.show();

Button btnPositive = alertDialog.getButton(AlertDialog.BUTTON_POSITIVE);
Button btnNegative = alertDialog.getButton(AlertDialog.BUTTON_NEGATIVE);

LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) btnPositive.getLayoutParams();
layoutParams.weight = 10;
btnPositive.setLayoutParams(layoutParams);
btnNegative.setLayoutParams(layoutParams);

Solution 4

Here is something really work.

The parent of the 3 buttons (neutral, positive ve and negative) is ButtonBarLayout, which extends LinearLayout. To centralize a view in LinearLayout, weight, width and layout_gravity(but not gravity) is important, and these code works perfectly:

LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT); //create a new one
layoutParams.weight = 1.0 f;
layoutParams.gravity = Gravity.CENTER; //this is layout_gravity
alertDialog.getButton(AlertDialog.BUTTON_NEGATIVE).setLayoutParams(layoutParams);

Solution 5

Tried crtn's method and Scott Brown's modification, both didn't render how I liked.

crtn's solution didn't change the appearance of the buttons for me at all (I'm using android.R.style.Theme_Material_Light_Dialog) and Scott Brown's solution made my positive button extend past the edge of the dialog parent.

For Theme_Material_Light_Dialog the buttons are contained within a LinearLayout subclass that uses a blank View as its 2nd (index 1) element to push the buttons right.

I grab the Button ref like crtn does:

AlertDialog dialog = bld.create();
dialog.show(); //show() MUST be called before dialog.getButton
Button positiveButton = dialog.getButton(AlertDialog.BUTTON_POSITIVE);

But then I set the leftSpacer to View.GONE and the parent's gravity to CENTER_HORIZONTAL

LinearLayout parent = (LinearLayout) positiveButton.getParent();
parent.setGravity(Gravity.CENTER_HORIZONTAL);
View leftSpacer = parent.getChildAt(1);
leftSpacer.setVisibility(View.GONE);

This has the advantage that it doesn't break the dialog's button stacking behavior. The disadvantage is that if the internal layout changes, it will break, so YMMV.

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