driver.findElement(By.xpath("//*[@id="loginUsername"]")).sendKeys("username");
driver.findElement(By.xpath("//*[@id="loginPassword"]")).sendKeys("password");

WebElement username = driver.findElement(By.xpath("//*[@id="loginUsername"]")); username.click(); username.clear(); ;username.sendKeys("username");
WebElement password = driver.findElement(By.xpath("//*[@id="loginPassword"]")); password.click(); password.clear(); ;password.sendKeys("password");