无法从MySQL数据库中检索数据并将其放在我的Android应用程序的列表视图中

Question

I'm trying to do a search function on my database. I first tried to retrieve all data from my database and put it into a listview and then performed a search on that list. The problem is that my app doesn't put those retrieved data from my SQL database to the listview. I tried running my PHP code separately and it works, so I think it's a problem in my java code in android.

companylist.php

<?php
include 'db_connect.php';

$sql = "SELECT * FROM company";

$result = $con->query($sql);

if ($result->num_rows >0) {


 while($row[] = $result->fetch_assoc()) {

 $tem = $row;

 $json = json_encode($tem);


 }

} else {
 echo "No Results Found.";
}
 echo $json;
$con->close();
?>

Search.java

package com.example.activitymanagement;

import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.Toast;

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

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

public class Search extends Fragment {

    ListView SubjectListView;
    ProgressBar progressBarSubject;
    String ServerURL = "http://10.0.2.2/member/companylist.php";
    EditText editText ;
    List<String> listString = new ArrayList<String>();
    ArrayAdapter<String> arrayAdapter ;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //returning our layout file
        //change R.layout.yourlayoutfilename for each of your fragments
        //return inflater.inflate(R.layout.fragment_search, container, false);

        View rootView = inflater.inflate(R.layout.fragment_search, container, false);

        SubjectListView = (ListView)rootView.findViewById(R.id.listview1);

        progressBarSubject = (ProgressBar)rootView.findViewById(R.id.progressBar);

        editText = (EditText)rootView.findViewById(R.id.edittext1);

        new GetHttpResponse(getActivity()).execute();

        editText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

                Search.this.arrayAdapter.getFilter().filter(charSequence);

            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void afterTextChanged(Editable editable) {

            }
        });
        return rootView;
    }


    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        //you can set the title for your toolbar here for different fragments different titles
        getActivity().setTitle("Search");
    }

    private class GetHttpResponse extends AsyncTask<Void, Void, Void>
    {
        public Context context;

        String ResultHolder;

        public GetHttpResponse(Context context)
        {
            this.context = context;
        }

        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... arg0)
        {
            HttpServicesClass httpServiceObject = new HttpServicesClass(ServerURL);
            try
            {
                httpServiceObject.ExecutePostRequest();

                if(httpServiceObject.getResponseCode() == 200)
                {
                    ResultHolder = httpServiceObject.getResponse();

                    if(ResultHolder != null)
                    {
                        JSONArray jsonArray = null;

                        try {
                            jsonArray = new JSONArray(ResultHolder);

                            JSONObject jsonObject;

                            for(int i=0; i<jsonArray.length(); i++)
                            {
                                jsonObject = jsonArray.getJSONObject(i);

                                listString.add(jsonObject.getString("subjects").toString()) ;

                            }
                        }
                        catch (JSONException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                }
                else
                {
                    Toast.makeText(context, httpServiceObject.getErrorMessage(), Toast.LENGTH_SHORT).show();
                }
            }
            catch (Exception e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void result)

        {
            progressBarSubject.setVisibility(View.GONE);

            SubjectListView.setVisibility(View.VISIBLE);

            arrayAdapter = new ArrayAdapter<String>(getActivity(),android.R.layout.simple_list_item_2, android.R.id.text1, listString);

            SubjectListView.setAdapter(arrayAdapter);

        }
    }

}

fragment_search.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/searchlayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin">

    <EditText
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/edittext1"
        android:hint="Search Here"
        android:gravity="center"/>

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:visibility="visible"
        />

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listview1"
        android:layout_below="@id/edittext1" />

</RelativeLayout>

Answer 1

According your companylist.php file response you are getting wrong parameter inside response, instead of getting name you are getting subjects , please check below code

try {
    JSONArray jsonArray=new JSONArray(ResultHolder);
    for(int i=0;i<jsonArray.length();i++){
        JSONObject jsonObject=jsonArray.getJSONObject(i);
        listString.add(jsonObject.getString("name")) ;
    }
} catch (JSONException e) {
    e.printStackTrace();
}