Android Alert Dialog

alert_dialog.java

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
            }
        });
        builder.setNegativeButton("CANCEL", null);

        TextView view = new TextView(this);
        view.setText("A dialog");
        view.setPadding(20, 20, 20, 20);
        view.setGravity(Gravity.FILL_HORIZONTAL);
        view.setTextSize(18);

        builder.setView(view);
        builder.setTitle("Dialog title");
        builder.create().show();