解析Android和自定义列表视图

Question

我使用导航抽屉活动。我想从URL获取数据后显示自定义列表。这是我的导航抽屉活动。

例如：当用户单击导航抽屉上的分配选项卡时，分配活动将显示，并显示具有显示URL数据的自定义列表视图。

@Override 
    public boolean onNavigationItemSelected(MenuItem item) { 
     // Handle navigation view item clicks here. 
     int id = item.getItemId(); 
    if (id == R.id.nav_dashboard) { 
    switch (item.getItemId()) {case R.id.nav_dashboard: 
    startActivity(new Intent(this, AdminDashBoardActivity.class)); 
        // Handle the camera action 
      } } 
else if (id == R.id.nav_allocations) { 
    switch (item.getItemId()) {case R.id.nav_allocations: 
       startActivity(new Intent(this, 

     AdminAllocationActivity.class)); 
       break; 
       // Handle the camera action 
      } 

     } else if (id == R.id.nav_courseoutline) { 

      switch (item.getItemId()) { 
       case R.id.nav_courseoutline: 
        startActivity(new Intent(this, CourseOutlineActivity.class)); } 
     } else if (id == R.id.nav_ranklist) { 
       switch (item.getItemId()) {case R.id.nav_ranklist: 
        startActivity(new Intent(this,AllocatedTrainerActivity .class)); 
     }} 
// else if (id == R.id.nav_send) { 
// 
//  } 

     DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
     drawer.closeDrawer(GravityCompat.START); 
     return true; 
    } 

时分配标签在用户点击后进行自定义列表上的解析数据的分配活动开，并显示结果，但情况并非如此。请指导我。这是我的分配活动。

package vu.bc110201891.btg.AdminActivities; 

import android.content.Intent; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.widget.ListView; 

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

import vu.bc110201891.btg.Adapters.AdminAllocationAdapter; 
import vu.bc110201891.btg.AsyncTasks.AdminAllocationTask; 
import vu.bc110201891.btg.Models.AdminAllocation; 
import vu.bc110201891.btg.R; 

public class AdminAllocationActivity extends AppCompatActivity { 
    String json_string; 
    JSONObject jsonObject; 
    JSONArray jsonArray; 
    ListView listView; 
    AdminAllocationAdapter contactAdapter; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_admin_allocation); 

     listView= (ListView) findViewById(R.id.listView); 

     contactAdapter=new AdminAllocationAdapter(this,R.layout.activity_admin_allocation); 
     listView.setAdapter(contactAdapter); 

     json_string=getIntent().getExtras().getString("json_data"); 
     try { 
      jsonObject=new JSONObject(json_string); 
      jsonArray=jsonObject.getJSONArray("courseDataSet"); 

      int count=0; 
      String name,email,moblile; 

      while (count<jsonArray.length()){ 


       JSONObject JO=jsonArray.getJSONObject(count); 
       name=JO.getString("id"); 
       email= JO.getString("company_id"); 
       moblile=JO.getString("user_id"); 
       AdminAllocation contacts=new AdminAllocation(name,email,moblile); 
       contactAdapter.add(contacts); 
       count++; 
      } 


     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } 
} 

这是我的贴纸。

package vu.bc110201891.btg.Adapters; 

import android.content.Context; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ArrayAdapter; 
import android.widget.TextView; 

import java.util.ArrayList; 
import java.util.List; 

import vu.bc110201891.btg.Models.AdminAllocation; 
import vu.bc110201891.btg.R; 

/** 
* Created by bc120402700 on 9/23/2016. 
*/ 
public class AdminAllocationAdapter extends ArrayAdapter { 




    List list=new ArrayList(); 
    public AdminAllocationAdapter(Context context, int resource) { 
     super(context, resource); 
    } 



    public void add(AdminAllocation object) { 
     super.add(object); 
     list.add(object); 
    } 

    @Override 
    public int getCount() { 
     return list.size(); 
    } 
    @Override 
    public Object getItem(int position) { 
     return list.get(position); 
    } 

    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
     View row; 
     row=convertView; 
     AllocationHolder contactHolder; 
     if (row==null){ 


      LayoutInflater layoutInflater= (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      row=layoutInflater.inflate(R.layout.row_allocation,parent,false); 
      contactHolder=new AllocationHolder(); 
      contactHolder.tx_name= (TextView) row.findViewById(R.id.textView2); 
      contactHolder.tx_email= (TextView) row.findViewById(R.id.textView3); 
//   contactHolder.tx_mobile= (TextView) row.findViewById(R.id.tx_mobile); 
      row.setTag(contactHolder); 
     } 

     else { 

      contactHolder=(AllocationHolder)row.getTag(); 


     } 
     AdminAllocation contacts= (AdminAllocation) this.getItem(position); 
     contactHolder.tx_name.setText(contacts.getName()); 
     contactHolder.tx_email.setText(contacts.getEmail()); 
     contactHolder.tx_mobile.setText(contacts.getMobile()); 
     return row; 
    } 
static class AllocationHolder{ 
TextView tx_name,tx_email,tx_mobile; 
} 
} 

这是我的asyn任务。

package vu.bc110201891.btg.AsyncTasks; 
import android.app.ProgressDialog; 
import android.content.Context; 
import android.os.AsyncTask; 
import android.widget.Button; 
import android.widget.TextView; 

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.URL; 
import vu.bc110201891.btg.R; 

/** 
* Created by bc120402700 on 9/23/2016. 
*/ 
public class AdminAllocationTask extends AsyncTask<Void, Void, String> { 
    String json_url; 
@Override 
    protected void onPreExecute() { 
     json_url = "http://mantis.vu.edu.pk/bridging_the_gap/public/AllocateAdminService"; 
    } 
    String JSON_STRING; 
    @Override 
    protected String doInBackground(Void... voids) { 
try { 
URL url = new URL(json_url); 
      HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection(); 
      InputStream inputStream = httpURLConnection.getInputStream(); 
      BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); 
      StringBuilder stringBuilder = new StringBuilder(); 

      while ((JSON_STRING = bufferedReader.readLine()) != null) { 

       stringBuilder.append(JSON_STRING + "\n"); 

      } 
      bufferedReader.close(); 
      inputStream.close(); 
      httpURLConnection.disconnect(); 
      return stringBuilder.toString().trim(); 
} catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace()} 
     return null;} 
@Override 
    protected void onProgressUpdate(Void... values) { 
     super.onProgressUpdate(values); } 
@Override 
    protected void onPostExecute(String result) { 
super.onPostExecute(result);} 
} 

这是我的模型类。

package vu.bc110201891.btg.Models; 
public class AdminAllocation { 
private String name,email,mobile; 
public AdminAllocation(String name, String email, String mobile){ 
     this.name=name; 
     this.email=email; 
this.mobile=mobile; 
} public String getName() { 
     return name; 
    } 
public void setName(String name) { 
     this.name = name; 
    } 
public String getMobile() { 
     return mobile; 
    }public void setMobile(String mobile) { 
     this.mobile = mobile; 
    }public String getEmail() { 
     return email; } 
public void setEmail(String email) { 
     this.email = email; 
    } 
} 

Answer 1

设置适配器列表视图获取值之后

listView.setAdapter(contactAdapter); 

这种编码

json_string=getIntent().getExtras().getString("json_data"); 
     try { 
      jsonObject=new JSONObject(json_string); 
      jsonArray=jsonObject.getJSONArray("courseDataSet"); 

      int count=0; 
      String name,email,moblile; 

      while (count<jsonArray.length()){ 


       JSONObject JO=jsonArray.getJSONObject(count); 
       name=JO.getString("id"); 
       email= JO.getString("company_id"); 
       moblile=JO.getString("user_id"); 
       AdminAllocation contacts=new AdminAllocation(name,email,moblile); 
       contactAdapter.add(contacts); 
       count++; 
      } 


     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 

正确的代码

json_string=getIntent().getExtras().getString("json_data"); 
     try { 
      jsonObject=new JSONObject(json_string); 
      jsonArray=jsonObject.getJSONArray("courseDataSet"); 

      int count=0; 
      String name,email,moblile; 

      while (count<jsonArray.length()){ 


       JSONObject JO=jsonArray.getJSONObject(count); 
       name=JO.getString("id"); 
       email= JO.getString("company_id"); 
       moblile=JO.getString("user_id"); 
       AdminAllocation contacts=new AdminAllocation(name,email,moblile); 
       contactAdapter.add(contacts); 
       count++; 
      } 


     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 

    listView.setAdapter(contactAdapter);