Android Json解析错误字符串转换

我写了这段代码，然后ı写了httphandler等。但是当ı运行应用程序时，ı看到了错误：

.............

Java解析错误：Java.lang.String类型的值无法转换为JSONObject
ı在互联网上搜索，但ı无法解决。怎么了？ı应该在哪里添加代码

MainActivity.java

---

您需要接收JSON内容，但服务器正在返回HTML内容

修改服务器并将

应用程序/json

添加为内容类型：

Content-type:application/json

---

这是服务器端错误，请检查您的响应。这是服务器端错误。您需要一个json字符串，但服务器返回html类型的响应。谢谢。解决了这个问题，只是忘记了字符串url=“htt p://api.androidhive.info/contacts/”中的“s”；应该是“https”

import android.util.Log;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;

public class HttpHandler {

    private static final String TAG = HttpHandler.class.getSimpleName();

    public HttpHandler() {
    }

    public String makeServiceCall(String reqUrl) {
        String response = null;
        try {
            URL url = new URL(reqUrl);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            // read the response
            InputStream in = new BufferedInputStream(conn.getInputStream());
            response = convertStreamToString(in);
        } catch (MalformedURLException e) {
            Log.e(TAG, "MalformedURLException: " + e.getMessage());
        } catch (ProtocolException e) {
            Log.e(TAG, "ProtocolException: " + e.getMessage());
        } catch (IOException e) {
            Log.e(TAG, "IOException: " + e.getMessage());
        } catch (Exception e) {
            Log.e(TAG, "Exception: " + e.getMessage());
        }
        return response;
    }

    private String convertStreamToString(InputStream is) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();

        String line;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line).append('\n');
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return sb.toString();
    }
}       

Content-type:application/json