Why syntax is driver.manage().window().maximize()?

Introduction

We frequently used the below kinds of method chaining statements in Selenium WebDriver scripts. This is a frequently asked interview question as well and you may be asked to explain the syntax. We are going to learn the same here.

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

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Method Chaining

The above syntaxes are written using Method Chaining concepts of Java. Let’s learn the method chaining concept with a simple Java example.

We have three class as below:-

Class NewDemo

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

Class AnotherDemo

This class has a method that returns a type reference of NewDemo class ( First one).

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

Class Demo

This class has a method that returns a type of AnotherDemo. (Second class).

public class Demo {

  // A method with return type AnotherDemo
  public AnotherDemo DemoMethod() {
    System.out.println("DemoMethod");
    return new AnotherDemo();
  }

  public static void main(String[] args) {
    // Creating an object of Demo class
    Demo DemoObject = new Demo();
    // Calling DemoMethod() that returns a type of AnotherDemo and storing its return value 
    AnotherDemo AnotherDemoObject = DemoObject.DemoMethod();
    // Since we have a reference of AnotherDemo then we can call method of AnotherDemo
    NewDemo NewDemoObject = AnotherDemoObject.AnotherDemoMethod();
    NewDemoObject.NewDemoMethod();

    // method chaining
    Demo DemoObject1 = new Demo();
    DemoObject1.DemoMethod().AnotherDemoMethod().NewDemoMethod(); // Method chaining

  }
}

Explanation

1. There is a total of three classes “Demo“, “AnotherDemo” and “NewDemo“.
2. Class “Demo” has a method “DemoMethod” that returns an object or type of class “AnotherDemo“.
3. Class “AnotherDemo” has a method “AnotherDemoMethod” that returns an object of class “NewDemo“.
4. Class “NewDemo” has a method “NewDemoMethod” that returns void.

5. You can understand from the above steps that all three classes are connected or a point of connection.
6. Class “Demo” has a main method and we will write call methods here.
7. We created an object of “Demo” that enables us to call its method “DemoMethod()” that returns an object of class “AnotherDemo“. We can store the return type of a method in an appropriate type and here we can use a reference variable of type “AnotherDemo“.

Demo DemoObject = new Demo(); 
AnotherDemo AnotherDemoObject = DemoObject.DemoMethod();

8. As we get an object of class “AnotherDemo” that enables us to call its method “AnotherDemoMethod()” that returns an object of class “NewDemo“. We can store the return type of a method in an appropriate type and here we can use a reference variable of type “NewDemo“. Since we get an object of “NewDemo” class then call its method as well.

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

If you understand the pattern from the above example then you must have understood that there are multiple method calls in parts. To call the next method we are storing reference and then using it to call the next method.

We can directly create a chain instead of storing reference variables. This is called method chaining and anonymous object. When we need to use an object once in a program, we can go for an anonymous object for better memory utilization.

The way of achieving method chaining is explained below the image.

Understand driver.manage().window().maximize()

You must have got an idea about this syntax now. This is also written using the Method chaining concept.

There is a method named “manage()” and declared In WebDriver interface. The return type of this method is Options. The Options interface is a subinterface of WebDriver interface. The Options interface has a method “window()” that returns an Interface type Window and that is also a subinterface of WebDriver interface. The Window interface has a method “maximize()” that returns void.

By following the above coding approach you need to write multiple lines of code as below –

WebDriver driver= new ChromeDriver();
Options optnObj= driver.manage();
Window winObj= optnObj.window();
winObj.maximize();

And if we follow method chaining then it can be written in fewer lines as –

See complete code below:

WebDriver driver= new ChromeDriver();
driver.manage().window().maximize();

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