An alpha version of Selenium is released as 4.0.0-alpha-1. Though release is not announced officially by Selenium guys yet (April 28, 2019) . You can check their official website www.seleniumhq.org/download and observe that they have not updated anything about Selenium 4 Alpha release. 

But Selenium 4 alpha is available to download at MVN Repository and also zip file can be downloaded from here.

New Features

I am going to list out some new features of Selenium 4 for Java binding here:-

1. Now you can launch a new tab and window and by default switch to it. “newWindow” method from “WebDriver” interface creates a new browser window and switches the focus for future commands of this driver to the new window.
2. You can capture (Screenshot) a particular web element directly instead of capturing whole screen. Earlier it was possible by cropping it using dimensions.
3. Selects class overrides equals() and hashcode() methods now.
4. Location of safari driver now configurable using “webdriver.safari.driver” system property.
5. Basic support for using Docker containers with the new Grid Server.
6. Selenium Grid will be robust as new Grid Server, supports “standalone”, “hub”, “node”, and completely distributed usage.
7. HtmlUnitDriver will not be default part of Selenium WebDriver now.
8. WebDriver implementation for Opera Browser is now removed :(Hence  there won’t be OperaDriver class in the WebDriver API in Selenium 4).They removed it as Opera and Chrome are based on Chromium And the OperaDriver is a wrapper over ChromeDriver .They are suggesting the Opera users to test on Chrome Browser to some extent.
9. Removed Support for PhantomJS Headless mode :They are suggesting to use Chrome and Firefox Browsers in headless mode instead .
10. Added driver.switchTo().parentFrame() method to switch directly to the parent frame.
11. All window manipulation methods are now supported .
12. Replaced WebElement().getSize() and WebElement.getLocation() methods with a single method WebElement.getRect() .
13. Removed timeouts() method in driver.manage() : Suggesting to use getTimeouts() and setTimeouts() methods instead.
14. Added getRect(), setRect(), fullScreen() and minimize() methods in driver.manage().window()
15. Removed getPosition(), setPosition(), getSize() and setSize() methods Suggesting to use getRect() and setRect() methods instead

For reference visit :
https://github.com/SeleniumHQ/selenium/blob/master/java/CHANGELOG