Generic method for Calendar view appium android

I am automating android app using Appium (java).
In calendar view , I found some links and made this method:

public static void setDatePicker(AppiumDriver<MobileElement> driver,String mon,String dt,String year){
        driver.findElement(By.xpath("//android.widget.NumberPicker[@index='0']")).sendKeys(mon);
        driver.findElement(By.xpath("//android.widget.NumberPicker[@index='1']")).sendKeys(dt);
        driver.findElement(By.xpath("//android.widget.NumberPicker[@index='2']")).sendKeys(year);
    }

However ,this is not working properly.
Can anyone tell me what mistake I am doing in this or any workaround for calendar view that is working for you.