Android中java.lang.StringIndexOutOfBoundsException的完整验证检查

仍在获取java.lang.StringIndexOutOfBoundsException:index=0 length=0下面代码中的错误，位于

if（result.charAt（0）='Y'）

如果（result==null | | | result.isEmpty（）），还有其他更好的方法检查

中的空字符串吗？由于某些原因，未拾取空字符串“result”或
activity.finish（）未执行，下一个if语句是否已执行？请帮忙

@Override
    protected void onPostExecute(String result) {

        //check if result null or empty
        if (result == null || result.isEmpty()) {

            Toast.makeText(context, "Could Not Check For Updates, Please Try Again. Closing Application.", Toast.LENGTH_LONG).show();
            activity.finish();
        }           
        //update available
        if (result.charAt(0) =='Y') {

            UpdateAlert();
        }
        //no update available
        else if (result.charAt(0) =='N') {

            Toast.makeText(context, "No Updates Available", Toast.LENGTH_SHORT).show();             
        }
        else {

            Toast.makeText(context, "Could Not Check For Updates, Please Try Again. Closing Application : " + result, Toast.LENGTH_LONG).show();
            activity.finish();
        }   

遇到下面修改的无效结果时，尝试从方法返回

//check if result null or empty         
           if (result == null || result.isEmpty()) {              
                Toast.makeText(context, "Could Not Check For Updates, Please Try Again. Closing Application.", Toast.LENGTH_LONG).show();             
                activity.finish();         
                return;
           }  

试着接受你合适的答案，让你的问题更接近你。
   if (result == null || result.trim().length()==0) {
         Toast.makeText(context, "Could Not Check For Updates, Please Try Again. Closing  Application.", Toast.LENGTH_LONG).show();
            activity.finish();
        }           
        //update available
        else if (result.charAt(0) =='Y') {
        ^^^^ 
            UpdateAlert();
        }