在Android App中使用Volley Library解析对象数据

Question

使用此https://www.thorntech.com/2016/03/parsing-json-android-using-volley-library/了解如何使用Volley从api获取路线访问和解析对象数据。

当我安装apk并启动应用程序时，屏幕上没有显示来自此api获取路线的解析对象（单个用户） https://reqres.in/api/users/2

知道为什么吗？ 我以前从未使用过凌空抽射，但是整个周末我都读过它，它很容易理解和实现，但是很明显，我在指向数据或响应对象方面做错了。

感谢您为我指明正确方向的帮助。

    package com.volleythorntech.example;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONException;
import org.json.JSONObject;


public class MainActivity extends AppCompatActivity {
    // Will show the string "data" that holds the results
    TextView results;
    // URL of object to be parsed
    String JsonURL = "https://reqres.in/api/users/2";
    // This string will hold the results
    String data = "";
    // Defining the Volley request queue that handles the URL request concurrently
    RequestQueue requestQueue;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Creates the Volley request queue
        requestQueue = Volley.newRequestQueue(this);

        // Casts results into the TextView found within the main layout XML with id jsonData
        results = (TextView) findViewById(R.id.jsonData);

        // Creating the JsonObjectRequest class called obreq, passing required parameters:
        //GET is used to fetch data from the server, JsonURL is the URL to be fetched from.
        JsonObjectRequest obreq = new JsonObjectRequest(Request.Method.GET, JsonURL,
                // The third parameter Listener overrides the method onResponse() and passes
                //JSONObject as a parameter
                new Response.Listener<JSONObject>() {

                    // Takes the response from the JSON request
                    @Override
                    public void onResponse(JSONObject response) {
                        try {
                            JSONObject obj = response.getJSONObject("data");
                            // Retrieves the string labeled "colorName" and "description" from
                            //the response JSON Object
                            //and converts them into javascript objects
                            String color = obj.getString("first_name");
                            String desc = obj.getString("last_name");

                            // Adds strings from object to the "data" string
                            data += "Color Name: " + color +
                                    "nDescription : " + desc;

                            // Adds the data string to the TextView "results"
                            results.setText(data);
                        }
                        // Try and catch are included to handle any errors due to JSON
                        catch (JSONException e) {
                            // If an error occurs, this prints the error to the log
                            e.printStackTrace();
                        }
                    }
                },
                // The final parameter overrides the method onErrorResponse() and passes VolleyError
                //as a parameter
                new Response.ErrorListener() {
                    @Override
                    // Handles errors that occur due to Volley
                    public void onErrorResponse(VolleyError error) {
                        Log.e("Volley", "Error");
                    }
                }
        );
        // Adds the JSON object request "obreq" to the request queue
        requestQueue.add(obreq);
    }
}

Answer 1

请检查清单中的权限

<uses-permission android:name="android.permission.INTERNET"/>