How does Selenium use Java Interface?

To overcome this problem, Selenium Developers have created an Interface called “WebDriver” and defined all the must-have methods inside it without implementing it.

Any class implementing the WebDriver Interface now has to use and implement the same set of methods, or Java will throw an error.
As a result, whether it’s Chrome, Edge, Firefox, or Safari, all the implementing classes must have the same set of methods with the same name.

This is how the Interface achieves abstraction, i.e. hiding all the implementing parts for various browsers, getting the method name, and using it in your code.

In the below image, the WebDriver interface and its methods are shown in the centre. These methods are not implemented yet. The classes are mentioned in the circle that implement the WebDriver interface.

WebDriver Interface

Below is the Java program to implement interface:

Java

// Java program to implement
// Interface
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
 
public class InterfaceExample {
    public static void main(String args[])
        throws InterruptedException
    {
        WebDriver driver = new ChromeDriver();
        driver.manage().window().maximize();
        driver.get(
            "https://demo.automationtesting.in/Register.html");
        WebElement element = driver.findElement(
            By.xpath("//input[@placeholder='First Name']"));
        element.sendKeys("Selenium");
        driver.quit();
    }
}

Explanation:

WebDriver driver = new ChromeDriver(): Here WebDriver is an Interface and ChromeDriver is the implementing class.
driver.get(): get() method is declared in WebDriver Interface. Hence the ChromeDriver class must define the method get(), which is used to open a URL on the Chrome Browser. Similarly, FirefoxDriver implements the method get() to open a URL on the Firefox Browser.
driver.findElement(): findElement() is another method that is declared in the WebDriver interface and all the classes that implement the WebDriver interface must define its definition. The same goes for driver.quit() as well.
element.sendKeys(): Enter a value in the text field.

Output:

Output

Understand Java Interface using Selenium WebDriver

Java Interface is a blueprint of the class that contains static constants and abstract methods. It cannot have a method body. The interface is a mechanism to achieve abstraction. This article focuses on discussing the Selenium WebDriver Interface.

Example:

public interface Animal

{

void printAnimalName();

void printAnimalColor();

void printAnimalWeight();

}

In the above example, an Interface “Animal” is created and three non-implemented methods are declared. Now, it’s just a blueprint, there is no implementation. Any class that implements this interface must implement the non-implemented methods, or Java will throw an error. Here is what the implemented class looks like. In the below class “Cat”, we have implemented the three non-implemented methods.

public class Cat implements Animal

{

@Override

public void printAnimalName()

{

System.out.println(“Cat”);

}

@Override

public void printAnimalColor()

{

System.out.println(“Black”);

}

@Override

public void printAnimalWeight()

{

System.out.println(“50”);

}

}