Need some help understanding this Selenium test script example
<p>I was reviewing this example and trying to understand how it works. The example is taken from <a href="http://www.tutorialspoint.com/selenium/selenium_page_object_model.htm" rel="nofollow">http://www.tutorialspoint.com/selenium/selenium_page_object_model.htm</a>.</p>

<p>Step1:</p>

<pre><code>package PageObject;

import org.openqa.selenium.*;

public class PageObjectsPercCalc 
{
   private static WebElement element = null;

   // Math Calc Link
   public static webElement lnk_math_calc(WebDriver driver)
   {
      element = driver.findElement(By.xpath(".//*[@id='menu']/div[3]/a"));
      return element;
   }

   //Percentage Calc Link
   public static webElement lnk_percent_calc(WebDriver driver)
   {
      element = driver.findElement(By.xpath(".//*@id='menu']/div[4]/div[3]/a"));
      return element;
   }

   //Number 1 Text Box
   public static webElement txt_num_1(WebDriver driver)
   {
      element = driver.findElement(By.id("cpar1"));
      return element;
   }

   //Number 2 Text Box  
   public static webElement txt_num_2(WebDriver driver)
   {
      element = driver.findElement(By.id("cpar2"));
      return element;
   }

   //Calculate Button   
   public static webElement btn_calc(WebDriver driver)
   {
      element = driver.findElement(By.xpath(".//*[@id='content']/table/tbody/tr/td[2]/input"));
      return element;
   }    

   // Result    
   public static webElement web_result(WebDriver driver)
   {
      element = driver.findElement(By.xpath(".//*[@id='content']/p[2]/span/font/b"));
      return element;
   }    
}
</code></pre>

<p>Step 2: Using above object library to create following test:</p>

<pre><code>package PageObject;

import java.util.concurrent.TimeUnit;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;

public class PercentCalculator {

   private static WebDriver driver = null;

   public static void main(String[] args) {

      driver = new FirefoxDriver();
      driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);
      driver.get("http://www.calculator.net");

      //Use page Object library now
      page_objects_perc_calc.lnk_math_calc(driver).click();     
      page_objects_perc_calc.lnk_percent_calc(driver).click();

      page_objects_perc_calc.txt_num_1(driver).clear();
      page_objects_perc_calc.txt_num_1(driver).sendKeys("10");      

      page_objects_perc_calc.txt_num_2(driver).clear();
      page_objects_perc_calc.txt_num_2(driver).sendKeys("50");  

      page_objects_perc_calc.btn_calc(driver).click();
      String result =  page_objects_perc_calc.web_result(driver).getText();

      if(result.equals("5")){      
         System.out.println(" The Result is Pass");
         }
      else {
         System.out.println(" The Result is Fail");

         }
      driver.close();
      }
   }
</code></pre>

<p>Now my question is how "page_objects_perc_calc" object is calling library methods without declaring it as the PageObjectsPercCalc in the second step? Now, if I declare it as below:</p>

<pre><code>PageObjectsPercCalc page_objects_perc_calc = new PageObjectsPercCalc();
</code></pre>

<p>I get this warning </p>

<blockquote>
  <p>"The static method lnk_math_calc(WebDriver) from the type
  PageObjectsPercCalc should be accessed in a static way";</p>
</blockquote>

<p>This is correct but I do not know how to define <code>PageObjectsPercCalc</code> object as static. Please help.</p>

<p>Thanks.</p>