When working on a project, you work on a set of files. You switch between them a lot, so knowledge of how to navigate efficiently between files, types, or methods is essential to speed up development. Basically, the faster you switch between files, the more productive you are.
IntelliJ IDEA provides a switcher between opened files and tool windows. It's similar to the application switcher in your operating system such as Alt + Tab on Windows or cmd + Tab on the Mac. The switcher in IntelliJ IDEA is available by using the Ctrl + Tab keyboard shortcut. If the switcher pop-up is visible, keep the Ctrl key pressed and use the Tab key (or the cursor + up and down arrow keys) to select the desired tool window or file. In the switcher, you will see only the files that are currently opened in the editor, as shown in the following screenshot:
The tab switcher
You can also use Alt + the left arrow key to switch to the previous tab and Alt + the right arrow...