字符串不能转换为JSONObject吗？

Question

I'm a beginner in developing Android apps and it's the first time I'd be coding from scratch that's why I find it very hard for me. Basically, I just want to get rid of the error so that I can now start with displaying the SQL table on my Android application. I am barred by this error as I was fetching the data from mySQL tables. I am getting this at LogCat:

Error parsing data org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject
05-03 15:45:25.586: W/System.err(552): java.lang.NullPointerException
05-03 15:45:25.626: W/System.err(552):  at hs.stockapp.StocksTask.doInBackground(StocksTask.java:64)

If I understood the error right, something's wrong with line 64 of my StocksTask.java file.

Line 64: if (json.getString(KEY_SUCCESS) != null)

StocksTask.java code excerpt:

protected Integer doInBackground(String... params)  {

    UserFunctions userFunction = new UserFunctions();
    JSONObject json = userFunction.findStocks();
    try {
        if (json.getString(KEY_SUCCESS) != null) {
            String res = json.getString(KEY_SUCCESS);

            if(Integer.parseInt(res) == 1){         
                DatabaseHandler db = new DatabaseHandler(activity.getApplicationContext());
                JSONObject json_stocks = json.getJSONObject("stocks");
                Log.v("company_name", json_stocks.getString(STOCK_COMPANY_NAME));
                userFunction.findStocks();
                db.findStocks(json_stocks.getString(STOCK_COMPANY_NAME), json_stocks.getString(STOCK_SYMBOL), json_stocks.getString(STOCK_MCAP));                        

                responseCode = 1;
                // Close Screen
                //finish();
            }else{
                responseCode = 0;
                // Error 
            }
        }
    }
    catch (NullPointerException e) {
        e.printStackTrace();
    }
    catch (JSONException e) {
        e.printStackTrace();
    }
    return responseCode;
}

UserFunctions.java

 public JSONObject findStocks(){
    // Building Parameters
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair("tag", findstocks_tag));
    JSONObject json = jsonParser.getJSONFromUrl(stocksURL, params);
    // return json
    return json;
} 

index.php

else if ($tag == 'stocks'){
    // request type is view stock list
    $stocks = $db->search_stocks();
    if ($stocks != false) {
        // stocks
        // echo json with success = 1
        $response["success"] = 1;
        $response["stocks"]["company_name"] = $stocks["name"];
        $response["stocks"]["com_sym"] = $stocks["com_sym"];
        $response["stocks"]["mkt_cap"] = $stocks["mkt_cap"];
        echo json_encode($response);
    } else {
        // no stocks found
        // echo json with error = 0
        $response["error"] = 1;
        $response["error_msg"] = "No stocks found";
        echo json_encode($response);
    }

} 

DB_functions.php

    public function search_stocks() {
    $result = mysql_query("SELECT company_name, com_sym, mkt_cap from stock ORDER BY com_sym") or die(mysql_error());
    $no_of_rows = mysql_num_rows($result);

    if ($no_of_rows > 0) {
        while($row=mysql_fetch_assoc($result)){
            $output[] = $row;
        }               
        print(json_encode($output)); 
        return $row;            
    return true;
    } else {
        // stocks not existed
        return false;
    }
mysql_close();  

}

Produced result of search_stocks function

[{"company_name":"Asian Chorva","com_sym":"ASIA","mkt_cap":"4534356"},{"company_name":"Banko de Oro","com_sym":"BDO","mkt_cap":"54434"},{"company_name":"Bank of the Phil Island","com_sym":"BPI","mkt_cap":"5464554"},{"company_name":"College Hive In Boon","com_sym":"CHIB","mkt_cap":"5434654"},{"company_name":"Critical Heart Throb Racing","com_sym":"CHTR","mkt_cap":"53544564654"}]

What should I do with Line 64?? MANY THANKS :) Any help will be greatly appreciated. Additional info about it will be very helpful.

Answer 1

The error message says:

Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject

If it is <!DOCTYPE then it isn't [{"company_name":… .

You need to figure out exactly what request is being made and why the server is returning an HTML document.

Check your server logs. It might be an error document.

Answer 2

正确检查您要在UserFunctions.java中显示为"http://10.0.2.2/api/"的url，其中api文件夹存储在www或htdocs文件夹中