Cross Browser Testing

/*
     * open browser method
     */
    public WebDriver openBrowser(String browser){
        if(browser.equalsIgnoreCase("firefox")){
            driver=new FirefoxDriver();
        }else if(browser.equalsIgnoreCase("chrome")){
            System.setProperty("webdriver.chrome.driver", "D:/Selenium/chromedriver.exe");
             driver = new ChromeDriver();
        }else if(browser.equalsIgnoreCase("ie")){
            System.setProperty("webdriver.ie.driver", "D:/Selenium/IEDriverServer.exe");
            driver = new InternetExplorerDriver();
        }
        return driver;
    }