如何顯示從web到用戶的元素到android的列表視圖android

Question

這裏我想顯示特定用戶的元素到android的列表視圖中，但在響應我得到了錯誤作爲「在json的字符0的輸入結束」以及nullpointerexception，所以任何人都可以向我建議解決方案！

//MainActivity.Java

import android.content.Intent; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ListAdapter; 
import android.widget.ListView; 
import android.widget.SimpleAdapter; 
import android.widget.TextView; 
import android.widget.Toast; 

import com.android.volley.AuthFailureError; 
import com.android.volley.DefaultRetryPolicy; 
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.StringRequest; 
import com.android.volley.toolbox.Volley; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.io.BufferedReader; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.Map; 

public class MainActivity extends AppCompatActivity implements View.OnClickListener { 

    private static final String REGISTER_URL = "http://xx.xx.xx.xx/api.php"; 

    public static final String KEY_USERNAME = "id"; 
    public static final String KEY_PASSWORD = "api_key"; 
    public static final String KEY_EMAIL = "type"; 

    ArrayList<HashMap<String, String>> contactList; 
    private EditText editTextUsername; 
    private EditText editTextEmail; 
    private EditText editTextPassword; 
    String result=""; 

    private ListView lv; 
    private Button buttonRegister; 
    private Button buttonLogin; 
    private TextView txtview; 
    private String TAG = MainActivity.class.getSimpleName(); 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     lv = (ListView) findViewById(R.id.list); 
     contactList = new ArrayList<>(); 
     // txtview=(TextView) findViewById(R.id.textView); 

     buttonLogin = (Button) findViewById(R.id.buttonLogin); 


     buttonLogin.setOnClickListener(this); 

    } 

    private void UserShow(){ 
     final String username = "117"; 
     final String password = "pass"; 
     final String email="get_earn"; 

     StringRequest stringRequest = new StringRequest(Request.Method.POST, REGISTER_URL, 
       new Response.Listener<String>() { 

        @Override 
        public void onResponse(String response) { 
         InputStream ss=null; 
         //convert response to string 
         try{ 
          //BufferedReader reader = new BufferedReader(new InputStreamReader(ss,"iso-8859-1"),8); 
          BufferedReader reader = new BufferedReader(new InputStreamReader(ss,"iso-8859-1"),8); 
          StringBuilder sb = new StringBuilder(); 
          String line = null; 
          while ((line = reader.readLine()) != null) { 
           sb.append(line + "\n"); 
          } 
          ss.close(); 
          result=sb.toString(); 
         }catch(Exception e){ 
          Log.e("log_tag", "Error converting result "+e.toString()); 
         } 
         try { 

          JSONObject jsonObj = new JSONObject(result); 

          // Getting JSON Array node 
          JSONArray contacts = jsonObj.getJSONArray("result"); 

          // looping through All Contacts 
          for (int i = 0; i < contacts.length(); i++) { 
           JSONObject c = contacts.getJSONObject(i); 
           String id = c.getString("name"); 
           String name = c.getString("disc"); 

           // tmp hash map for single contact 
           HashMap<String, String> contact = new HashMap<>(); 

           // adding each child node to HashMap key => value 
           contact.put("name", id); 
           contact.put("disc", name); 

           // adding contact to contact list 
           contactList.add(contact); 


          } 
         } catch (final JSONException e) { 
          Log.e(TAG, "Json parsing error: " + e.getMessage()); 
          runOnUiThread(new Runnable() { 
           @Override 
           public void run() { 
            Toast.makeText(getApplicationContext(), 
              "Json parsing error: " + e.getMessage(), 
              Toast.LENGTH_LONG).show(); 
           } 
          }); 

         } 
         Toast.makeText(MainActivity.this,response,Toast.LENGTH_LONG).show(); 

         ListAdapter adapter = new SimpleAdapter(MainActivity.this, contactList, 
           R.layout.list_item, new String[]{ "name","disc"}, 
           new int[]{R.id.email, R.id.mobile}); 
         lv.setAdapter(adapter); 


        } 

       }, 
       new Response.ErrorListener() { 
        @Override 
        public void onErrorResponse(VolleyError error) { 
         Toast.makeText(MainActivity.this,error.toString(),Toast.LENGTH_LONG).show(); 
        } 
       }){ 
      @Override 
      protected Map<String,String> getParams(){ 
       Map<String,String> params = new HashMap<String, String>(); 
       params.put("id","username"); 
       params.put("api_key","pasword"); 
       params.put("type", "email"); 
       return params; 
      } 

     }; 

     stringRequest.setRetryPolicy(new DefaultRetryPolicy(50000, 
       DefaultRetryPolicy.DEFAULT_MAX_RETRIES, 
       DefaultRetryPolicy.DEFAULT_BACKOFF_MULT)); 

     RequestQueue requestQueue = Volley.newRequestQueue(this); 
     requestQueue.add(stringRequest); 
    } 

    @Override 
    public void onClick(View v) { 
     if(v == buttonRegister){ 
      registerUser(); 
     } 
     if(v == buttonLogin){ 
      UserShow(); 
     } 
    } 


} 

Answer 1

你並不需要在這裏處理InutStream事情......你已經得到響應中爲onResponse字符串（）作爲PARAM。只要將它轉換成JSON對象和過程。總之只是刪除

InputStream ss=null; 
        //convert response to string 
        try{ 
         //BufferedReader reader = new BufferedReader(new InputStreamReader(ss,"iso-8859-1"),8); 
         BufferedReader reader = new BufferedReader(new InputStreamReader(ss,"iso-8859-1"),8); 
         StringBuilder sb = new StringBuilder(); 
         String line = null; 
         while ((line = reader.readLine()) != null) { 
          sb.append(line + "\n"); 
         } 
         ss.close(); 
         result=sb.toString(); 
        }catch(Exception e){ 
         Log.e("log_tag", "Error converting result "+e.toString()); 
        } 

部分和轉換JSONObject jsonObj = new JSONObject(result); 到JSONObject jsonObj = new JSONObject(response);和處理jsonObj獲得intented信息。