Why syntax is “driver.manage().window().maximize();”?

Hello Folks,

In my last post, I explained about some useful methods of WebDriver. I got some comments to explain why do we write syntax as below:

driver.manage().window().maximize(); // To maxmize
driver.navigate().to("some url"); // To open url
driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);// To set implicit time

Actually it’s JAVA concept. It is called as method chaining. We will learn about this now.

Some basic Concepts of JAVA:
1. There can be two types of members in a java class. Static and Non-static.
2. Static methods can be called using class name or by creating an object of that class but calling by class name is perfect practice.
3. Non-static members of class can be called only through object of class.
4. A method can return a type. It may be class or interface as well.

#JAVACODE to learn how to call static and non-static methods:

public class Demo {

	void NonStaticMethod()
	{
		System.out.println("Non static method");
	}
	
	static void StaticMethod()
	{
		System.out.println("static method");
	}
	
	
	public static void main(String[] args) {
		
		Demo.StaticMethod();
		Demo object= new Demo();
		object.NonStaticMethod();
		object.StaticMethod(); // Not preferred 
	}
}

Outout:
static method
Non static method
static method

#JavaCode to understand method chaining:

class AnotherDemo
{
	public NewDemo AnotherDemoMethod()
	{
		System.out.println("AnotherDemoMethod");
		return new NewDemo();
	}	
}

class NewDemo
{
	void NewDemoMethod()
	{
		System.out.println("NewDemoMethod");
	}
	
}

public class Demo {

	public AnotherDemo DemoMethod()
	{
		System.out.println("DemoMethod");
		return new AnotherDemo();
	}
	
	public static void main(String[] args) {
		
		Demo DemoObject= new Demo();
		AnotherDemo AnotherDemoObject= DemoObject.DemoMethod();
		NewDemo NewDemoObject= AnotherDemoObject.AnotherDemoMethod();
		NewDemoObject.NewDemoMethod();
		
		// method chaining
		Demo DemoObject1= new Demo();
		DemoObject1.DemoMethod().AnotherDemoMethod().NewDemoMethod(); // Method chaining
		
	}
}

Explanation:
1. There are total three classes “Demo”, “AnotherDemo” and “NewDemo”.
2. Class “Demo” has a method “DemoMethod” which return an object of class “AnotherDemo”.
3. Class “AnotherDemo” has a method “AnotherDemoMethod” which return an object of class “NewDemo”.
4. Class “NewDemo” has a method “NewDemoMethod” which return void.
5. Only class “Demo” has main method and through that method we want to access “NewDemoMethod” of class “NewDemo”.
6. We created an object of “Demo” to access method present in class “Demo”.

Demo DemoObject= new Demo();
7. Now, we will call “DemoMethod” of class “Demo” which returns an object of class “AnotherDemo”, which we can store in a variable of type “AnotherDemo”.

AnotherDemo AnotherDemoObject= DemoObject.DemoMethod();

8. Now what we have?? An object of class “AnotherDemo” means we can access methods of class “AnotherDemo”.
9. We call method “AnotherDemoMethod1” of class “AnotherDemo” which returns an object of class “NewDemo”, which we can store in a variable of type “NewDemo”.
NewDemo NewDemoObject= AnotherDemoObject.AnotherDemoMethod();

10. Now, we can access method of “NewDemo”.
NewDemoObject.NewDemoMethod();

11. So, now we have following lines of code:

Demo DemoObject= new Demo();
AnotherDemo AnotherDemoObject= DemoObject.DemoMethod();
NewDemo NewDemoObject= AnotherDemoObject.AnotherDemoMethod();
NewDemoObject.NewDemoMethod();

12. Now, refer the below image:

13. Above code has concepts of method chaining and anonymous object. When we need to use object once in a program, we can go for anonymous object for better memory utilization.

I hope above java concept must be clear.
Same logic is applied for selenium. I will explain one statement:
driver.manage().window().maximize();

When we call manage() method, it returns a “Options” type. “Options” is an interface.

public Options manage() 
{
return new RemoteWebDriver.RemoteWebDriverOptions();
}

Interface “Options” has method “windows” which returns “Window” type.

public interface Options {

WebDriver.Window window();
}

Now, we can use any method of interface “Window”. it has following methods which can be called.

public interface Window {
		void setSize(Dimension arg0);

		void setPosition(Point arg0);

		Dimension getSize();

		Point getPosition();

		void maximize();

		void fullscreen();
	}

See complete code below:

WebDriver driver= new ChromeDriver();
Options optnObj= driver.manage();
Window winObj= optnObj.window();
winObj.maximize();
		
// We can write above lines of code in one line as
driver.manage().window().maximize();

That’s it. I hope you must have learnt new thing. If still you have doubt,feel free to comment or do email.
I strongly believe when you know answer of both “how” and “Why”, you can write better scripts.

#HappyLearning
#Thanks