Initially, when building the class, there will be various private and public variables used that should be declared at the top of the class. This organizes the variables into one place in the file, but of course, this is a coding style guideline. Some of the common variables required to start are as follows:

public class CreateDriver {
    // local variables
    private static CreateDriver instance = null;
    private String browserHandle = null;
    private static final int IMPLICIT_TIMEOUT = 0;

    private ThreadLocal<WebDriver> webDriver =
            new ThreadLocal<WebDriver>();

    private ThreadLocal<AppiumDriver<MobileElement>> mobileDriver =
            new ThreadLocal<AppiumDriver<MobileElement>>();

    private ThreadLocal<String> sessionId =
            new ThreadLocal<String>();

    private ThreadLocal<String> sessionBrowser =
            new ThreadLocal<String>();

    private ThreadLocal<String> sessionPlatform =
            new ThreadLocal<String>();

    private ThreadLocal<String> sessionVersion =
            new ThreadLocal<String>();

    private String getEnv = null;
}