Java code to inject javascript and check for ExtJS Ajax error

SJTXE.java

//make sure it's run after every page load
public static void injectSJTXE(WebDriver driver) throws IOException {
  	URL url;
	String js;
	url = Resources.getResource(ExtJSUtil.class, "SJTXE.js");
	js = Resources.toString(url, Charsets.UTF_8);
	((JavascriptExecutor) driver).executeScript(js);
}

//code to check if there are ExtJS Ajax error
Boolean hasAjaxFailure = (Boolean) ((JavascriptExecutor) driver).executeScript("return SJTXE.hasAjaxFailure();");