getWindowHandles(): It is used to get the address of all open browsers, and its return data type is Set<String>.

getWindowHandle(): It is used to get the address of the current browser where the control is, and its return type is a string data type.

If the file is on the same machine or in a mapped network drive, it is really straightforward: We need to type the ‘path’ of the file in the FileUpload control. For example:

//Locate file selection input field 
WebElement uploadElement = driver.findElement(By.id("l"));

// enter the file path onto the file-selection input field
uploadElement.sendKeys("C:\\myfile.txt");

// click the "UploadFile" button
 driver.findElement(By.name("send")).click();

Data Driven Framework: A data-driven framework in Selenium is an approach of separating a 'dataset' from the actual 'test case' (code). This framework is completely dependent on the input test data. The test data is inserted from external sources such as an excel file, CSV file, or any database.

It also allows us to easily control how much data needs to be tested. We can easily increase the number of test parameters by adding more username and password fields to the excel file (or other sources).

Four parameters that need to be passed in Selenium are:

• Host
• Port number
• Browser
• URL

Here are the reason why Testers choose Selenium over QTP:

In Java, a special form of syntactic metadata can be added to Java source code, which is known as Annotations. Variables, parameters, packages, methods, and classes are annotated. Some of the JUnit Annotations are:

Below are difference between an Array and an Array list in Java

In Java, string objects are immutable in nature which simply means once the String object is created its state cannot be modified.

Whenever you try to update the value of that object instead of updating the values of that particular object, Java creates a new string object.

Java String objects are immutable as String objects are generally cached in the String pool. Since String literals are usually shared between multiple clients, action from one client might affect the rest. It enhances security, caching, synchronization, and performance of the application.

Below are the difference between String, String Builder and String Buffer.

In Java, constructor chaining is the process of calling one constructor from another with respect to the current object. Constructor chaining is possible only through legacy where a subclass constructor is responsible for invoking the superclass' constructor first. There could be any number of classes in the constructor chain. Constructor chaining can be achieved in two ways:

Within the same class using this()
From base class using super()