java - android 将 json 传递给 HashMap 到 alertdialog 中显示的 llistview

Question

我需要从 mysql 数据库中获取 2 列，所以我将它们传递到 HashMap 中，然后在警报对话框的 ListView 中显示它们，但我遇到了无法解决的错误

@Override
protected String doInBackground(String... params) {
    // TODO Auto-generated method stub
    int sucess;
    try {


        List<NameValuePair> Ext = new ArrayList<NameValuePair>();
        Ext.add(new BasicNameValuePair("NotificationID", NotificationID));
        json3 = jsonParser2.makeHttpRequest(Get_Ext,"POST", Ext);
        //json3 = jsonParser2.getJSONFromUrl(Get_Ext);
        //getExt = json3.getString("FieldTitle");
        //getExtVal=json3.getString("FieldValue");
        Rec2 = new JSONArray(getExt);
        final ArrayList<HashMap<String, String>> MyArrList = new ArrayList<HashMap<String, String>>();
        HashMap<String, String> map;
        for(int i = 0; i < Rec2.length(); i++){

        JSONObject c = Rec2.getJSONObject(i);

        map = new HashMap<String, String>();

        map.put("FieldTitle", c.getString("FieldTitle"));

        map.put("FieldValue", c.getString("FieldValue"));

        MyArrList.add(map);

        }

    } catch (Exception e) {
        // TODO: handle exception
    }


    return null ;
}

这里是我的onpostexecute:

@Override
protected void onPostExecute(String st){


    Toast.makeText(getApplicationContext(),  "done" , Toast.LENGTH_LONG).show();

    SimpleAdapter ExtAdpt = new SimpleAdapter(getApplicationContext(), MyArrList, R.layout.extended_message, new String[]{"FieldTitle","FieldValue"}, new int[]{R.id.ExtTitle, R.id.ExtMessage}); 
    AlertDialog.Builder alertDialogBuilder2 = new AlertDialog.Builder(Notifications.this);
    LayoutInflater inflat = getLayoutInflater();
    View turnview = (View) inflat.inflate(R.layout.extended_list, null);
    alertDialogBuilder2.setView(turnview);
    alertDialogBuilder2.setTitle("Call for Action ...");
    Extlist = (ListView) turnview.findViewById(R.id.extendedlst);
    Extlist.setAdapter(ExtAdpt);
    alertDialogBuilder2.create();
    alertDialogBuilder2.show();

我已经在浏览器上测试了我的 php 文件，它运行良好

我的日志

03-10 18:35:23.048: W/dalvikvm(1720): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
03-10 18:35:23.088: E/AndroidRuntime(1720): FATAL EXCEPTION: main
03-10 18:35:23.088: E/AndroidRuntime(1720): java.lang.NullPointerException
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.widget.SimpleAdapter.getCount(SimpleAdapter.java:93)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.widget.ListView.setAdapter(ListView.java:462)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at com.example.notifier.Notifications$GetExtended.onPostExecute(Notifications.java:492)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at com.example.notifier.Notifications$GetExtended.onPostExecute(Notifications.java:1)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.os.AsyncTask.finish(AsyncTask.java:631)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.os.AsyncTask.access$600(AsyncTask.java:177)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.os.Looper.loop(Looper.java:137)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at android.app.ActivityThread.main(ActivityThread.java:5041)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at java.lang.reflect.Method.invokeNative(Native Method)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at java.lang.reflect.Method.invoke(Method.java:511)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-10 18:35:23.088: E/AndroidRuntime(1720):     at dalvik.system.NativeStart.main(Native Method)

请帮帮我:'(

完整代码:

package com.example.notifier;

import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.List;
import java.util.zip.Inflater;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.google.android.gms.drive.metadata.internal.ParentDriveIdSet;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.SimpleCursorAdapter;
import android.widget.Spinner;
import android.widget.Toast;

public class Notifications extends Activity {

    Spinner tiFi , ty ;
    ProgressDialog progs;
    Button sh ;
    SqlCommands sql;
    String[] Fields , name , name2, name3;
    SimpleCursorAdapter Adpt ;
    ListView NotiLst , Extlist;
    ImageView Hip, Ntype , arr ;
    String getGrp_url = "http:///db_get_grp.php";
    String Get_Ext = "http:///get_Extended.php";
    String result , fld, bdy ,NotificationID , getExt , getExtVal;
    JSONParser jsonParser = new JSONParser();
    JSONParser jsonParser2 = new JSONParser();
    JSONObject json = null ;
    JSONObject json3 = null ;
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_Rec = "Grp_Name";
    private static final String TAG_RESULTS="result";
    ArrayList<HashMap<String, String>> MyArrList;
    JSONArray Rec = null;
    JSONArray Rec2 = null;
    JSONArray Rec3 = null;

    final List<String> list1 = new ArrayList<String>();
    final List<String> list2 = new ArrayList<String>();
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_home);

            tiFi = (Spinner) findViewById(R.id.timFilt);
            ty = (Spinner) findViewById(R.id.typFilt);      
           NotiLst = (ListView) findViewById(R.id.msgListView);
           Hip =(ImageView) findViewById(R.id.hi);
           Ntype =(ImageView) findViewById(R.id.Prio);
           sh =(Button) findViewById(R.id.dbadd);
            Extlist = (ListView) findViewById(R.id.extendedlst);    

          new GetGroup().execute();


    sh.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    // TODO Auto-generated method stub
            /*      sql = new SqlCommands(getApplicationContext());
                    Boolean x = sql.AddEntry(2,"aaaa","fggdfg",2,3,3,"2016-03-07");
                    if (x==true){
                        Toast.makeText(getApplicationContext(), "Done", Toast.LENGTH_LONG).show();
                    }
                    else {
                        Toast.makeText(getApplicationContext(), "not done", Toast.LENGTH_LONG).show();
                    }
                    CusListView();*/

                    Toast.makeText(getApplicationContext(),  NotificationID , Toast.LENGTH_LONG).show();
                }
                });




    /* tiFi.setOnItemSelectedListener(new OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView<?> arg0, View arg1,
                    int arg2, long arg3) {
                // TODO Auto-generated method stub
            switch (arg2) {
            case 0:


                break;

            default:
                break;
            }   
            }

            @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                // TODO Auto-generated method stub

            }
        });
         */       



    /*    
   arr.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Cursor c = sql.GetData();


        }
    });  
     */
      NotiLst.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
                // TODO Auto-generated method stub

                sql = new SqlCommands(getApplicationContext());
                Cursor cr = (Cursor) NotiLst.getItemAtPosition(position);

                //Cursor cr = sql.gettype((int) id);
                if (cr.moveToFirst()) 
                {
                    fld = cr.getString(cr.getColumnIndex("Types"));}

                switch (fld) {
                case "1":

                    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(Notifications.this);
                    alertDialogBuilder.setTitle("Message");
                      if (cr.moveToFirst()) 
                    {
                    bdy = cr.getString(cr.getColumnIndex("Body"));} 
                    alertDialogBuilder.setMessage(bdy);
                    alertDialogBuilder.create();
                    alertDialogBuilder.show();
                    break;

                case "2":

                      if (cr.moveToFirst()) 
                    {
                    NotificationID = cr.getString(cr.getColumnIndex("NotificationID"));
                    }   
                     new GetExtended().execute();  

                    break;
                }

                        }});




    String[] items = new String[]{"Ever", "Today", "Yseterday", "Last Week" , "Last Month" };
    ArrayAdapter<String> timAdpt = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, items);
   tiFi.setAdapter(timAdpt);
   tiFi.setOnItemSelectedListener(new OnItemSelectedListener() {

    @SuppressLint("NewApi")
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position,long id) {
        // TODO Auto-generated method stub
        sql = new SqlCommands(getApplicationContext());
        String[] mFields = new String[]{SqlCommands.Subject, SqlCommands.Body, SqlCommands.DateTime};
        int [] tview = new int []{R.id.sbj,R.id.bdy,R.id.DT};
        Calendar cal = Calendar.getInstance();
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        switch (position) {
        case 1:
            cal.add(Calendar.DATE, 0);
            String d = dateFormat.format(cal.getTime());
            Cursor c = sql.getDate(d)  ;
            SimpleCursorAdapter Dadpt = new SimpleCursorAdapter(getApplicationContext(),R.layout.items, c , mFields, tview ,0 );
            Dadpt.notifyDataSetChanged();
            NotiLst.setAdapter(Dadpt);

            break;
        case 2:
            cal.add(Calendar.DATE, -1);
            String d1 = dateFormat.format(cal.getTime());
            Cursor c1 = sql.getDate(d1)  ;
            SimpleCursorAdapter Dadpt1 = new SimpleCursorAdapter(getApplicationContext(),R.layout.items, c1 , mFields, tview ,0 );
            Dadpt1.notifyDataSetChanged();
            NotiLst.setAdapter(Dadpt1);
            break;
        case 3:
            cal.add(Calendar.DATE, 0);
            String d2 = dateFormat.format(cal.getTime());
            Cursor c2 = sql.getDateweek(d2)  ;
            SimpleCursorAdapter Dadpt2 = new SimpleCursorAdapter(getApplicationContext(),R.layout.items, c2 , mFields, tview ,0 );
            Dadpt2.notifyDataSetChanged();
            NotiLst.setAdapter(Dadpt2);
            break;
        case 4:
            cal.add(Calendar.DATE, -30);
            String d3 = dateFormat.format(cal.getTime());
            Cursor c3 = sql.getDate(d3)  ;
            SimpleCursorAdapter Dadpt3 = new SimpleCursorAdapter(getApplicationContext(),R.layout.items, c3 , mFields, tview ,0 );
            Dadpt3.notifyDataSetChanged();
            NotiLst.setAdapter(Dadpt3);
            break;

        default:
            CusListView();
            break;
        }
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        // TODO Auto-generated method stub

    }
});


}


public void spin(){
        ArrayAdapter<String> grpAdpt = new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, name);

        ty.setAdapter(grpAdpt);
        ty.setOnItemSelectedListener(new OnItemSelectedListener() {

        @SuppressLint("NewApi")
        @Override
        public void onItemSelected(AdapterView<?> parent, View view,int position, long id) {
            // TODO Auto-generated method stub

            //Toast.makeText(parent.getContext(), "The planet is " +parent.getItemAtPosition(position).toString(), Toast.LENGTH_LONG).show();
            switch (position) {
            case 0:
                CusListView();
                break;

            default:
                sql = new SqlCommands(getApplicationContext());
                Fields = new String[]{SqlCommands.Subject, SqlCommands.Body, SqlCommands.DateTime};
                int [] Dview = new int []{R.id.sbj,R.id.bdy,R.id.DT};
                //int P = (int)parent.getItemAtPosition(position);
                Cursor c = sql.getSpecificData(position)  ;
                SimpleCursorAdapter Adpt2 = new SimpleCursorAdapter(getApplicationContext(),R.layout.items, c , Fields, Dview ,0 );
                Adpt2.notifyDataSetChanged();
                NotiLst.setAdapter(Adpt2);
                break;
            } 


        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
            // TODO Auto-generated method stub

        }}); }





@SuppressLint("NewApi")
private void CusListView(){
sql = new SqlCommands(getApplicationContext());
Fields = new String[]{SqlCommands.Subject, SqlCommands.Body, SqlCommands.DateTime};
int [] Dview = new int []{R.id.sbj,R.id.bdy,R.id.DT};
Cursor c = sql.GetData();
Adpt = new SimpleCursorAdapter(getApplicationContext(),R.layout.items, c , Fields, Dview ,0 );
NotiLst.setAdapter(Adpt);

}

private void IsHigh(){
sql = new SqlCommands(getApplicationContext());

Cursor c = sql.GetData();
if (c.moveToFirst())
{
 do {
     int IShig = c.getColumnIndex("Priopity");
     if(IShig!=1){
     Hip.setVisibility(View.INVISIBLE); 
     }
     else {
         Hip.setVisibility(View.VISIBLE);   
     }
 } while (c.moveToNext());
}
sql.close();


}

public void showSpinner(){

    try {

    JSONObject json; 
    Rec = new JSONArray(result);
    name = new String[Rec.length()];

    for(int i=0;i<Rec.length();i++){

    json = Rec.getJSONObject(i);
    name[i] = json.getString("Grp_Name");
    }

    for (int i=0; i<name.length; i++){
    list1.add(name[i]);
    }

    spin();

    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}   


class GetGroup extends AsyncTask<String, String, String >{


    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub

        try{

             json = jsonParser.getJSONFromUrl(getGrp_url);

             Log.d("Login attempt", json.toString());
             result = json.getString("Grp_Name");

        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        return result;
    }
        @Override
        protected void onPostExecute(String result){

            showSpinner();

        }

}

class GetExtended extends AsyncTask<String, String, String>{

    @SuppressLint("NewApi")
    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub
        int sucess;
        try {


            List<NameValuePair> Ext = new ArrayList<NameValuePair>();
            Ext.add(new BasicNameValuePair("NotificationID", NotificationID));
            json3 = jsonParser2.makeHttpRequest(Get_Ext,"POST", Ext);
            //json3 = jsonParser2.getJSONFromUrl(Get_Ext);
            //getExt = json3.getString("FieldTitle");
            //getExtVal=json3.getString("FieldValue");
            Rec2 = new JSONArray();
            MyArrList = new ArrayList<HashMap<String, String>>();
            HashMap<String, String> map;
            for(int i = 0; i < Rec2.length(); i++){

            JSONObject c = Rec2.getJSONObject(i);

            map = new HashMap<String, String>();

            map.put("FieldTitle", c.getString("FieldTitle"));

            map.put("FieldValue", c.getString("FieldValue"));

            MyArrList.add(map);

            }

        } catch (Exception e) {
            // TODO: handle exception
        }


        return null ;
    }

    @Override
    protected void onPostExecute(String st){


        Toast.makeText(getApplicationContext(),  "done" , Toast.LENGTH_LONG).show();

        SimpleAdapter ExtAdpt = new SimpleAdapter(getApplicationContext(), MyArrList, R.layout.extended_message, new String[]{"FieldTitle","FieldValue"}, new int[]{R.id.ExtTitle, R.id.ExtMessage}); 
        AlertDialog.Builder alertDialogBuilder2 = new AlertDialog.Builder(Notifications.this);
        LayoutInflater inflat = getLayoutInflater();
        View turnview = (View) inflat.inflate(R.layout.extended_list, null);
        alertDialogBuilder2.setView(turnview);
        alertDialogBuilder2.setTitle("Call for Action ...");
        Extlist = (ListView) turnview.findViewById(R.id.extendedlst);
        Extlist.setAdapter(ExtAdpt);
        alertDialogBuilder2.create();
        alertDialogBuilder2.show();
}
}           
}

Answer 1

MyArrList 似乎是 doInBackground 方法的本地对象，您也没有从 doInBackground 方法返回。或者您正试图在 onPostExecute 中访问该对象，该对象为 null 或不退出。