Java 我正在使用Spinner，我想从mysql数据库中获取基于所选项目的数据，并将其放入Spinner中

/*我的代码如下。我试图在选择微调器项后从数据库中检索数据，但检索失败。请有人建议我正确的代码*/

main.xml

    <?xml version="1.0" encoding="utf-8"?>
    <TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/activity_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:stretchColumns="*"
        tools:context="com.example.jay.jobfinder.MainActivity">

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="20dp">

            <ImageView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                app:srcCompat="@drawable/logo"
                android:id="@+id/ivLogo"
                android:layout_span="2"
                android:layout_alignParentTop="true"
                android:layout_centerHorizontal="true" />
        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="20dp">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/tvState"
                android:text="@string/tvState"
                android:layout_span="2"
                android:textColor="#000000"
                android:textAppearance="@style/Base.TextAppearance.AppCompat.Medium"
                android:textStyle="normal|bold" />
        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="20dp">
            <Spinner
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_centerHorizontal="true"
                android:layout_span="2"
                android:id="@+id/spinner_state" />
        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="20dp">
            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/tvJob"
                android:text="@string/tvJob"
                android:textColor="#000000"
                android:textAppearance="@style/Base.TextAppearance.AppCompat.Medium"
                android:textStyle="normal|bold" />
        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="20dp">
            <RadioGroup
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@+id/rgJob">

                <RadioButton
                    android:text="Goverment"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:id="@+id/radioButton2" />

                <RadioButton
                    android:text="Private"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:id="@+id/radioButton" />
            </RadioGroup>
        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="20dp">
            <Button
                android:text="@string/btn_search"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:id="@+id/btnSearch"
                android:layout_span="2"/>
        </TableRow>

        <TableRow
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="20dp">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@+id/tvTag"
                android:layout_span="2"
                android:gravity="center_horizontal" />

        </TableRow>
    </TableLayout>

jobAdapter.java

package com.example.jay.jobfinder;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.pm.PackageInstaller;
import android.os.AsyncTask;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends Activity implements AdapterView.OnItemSelectedListener
{
    Spinner spinner_state;
    Button button;
    String city,job;
    TextView textView;
    RadioGroup rg;
    RadioButton rb;
    private session session;
    int rbId;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        session = new session(getApplicationContext());
        button=(Button)findViewById(R.id.btnSearch);
        textView=(TextView)findViewById(R.id.tvTag);
        textView.setText(city);
        rg=(RadioGroup)findViewById(R.id.rgJob);
        spinner_state=(Spinner)findViewById(R.id.spinner_state);
        spinner_state.setOnItemSelectedListener(this);
        final List<String> state = new ArrayList<String>();
        state.add("Andhra Pradesh");
        state.add("Arunachal Pradesh");
        state.add("Assam");
        state.add("Bihar");
        state.add("Chandigath");
        state.add("Chhattisgath");
        state.add("Delhi");
        state.add("Goa");
        state.add("Gujarat");
        state.add("Haryana");
        state.add("Himachal Pradesh");
        state.add("Jharkhand");
        state.add("Jammu and Kashmir");
        state.add("Karnataka");
        state.add("Kerala");
        state.add("Madhya Pradesh");
        state.add("Maharashtra");
        state.add("Manipur");
        state.add("Meghalaya");
        state.add("Mizoram");
        state.add("Nagaland");
        state.add("Odisha");
        state.add("Puducherry");
        state.add("Punjab");
        state.add("Rajashtan");
        state.add("Sikkim");
        state.add("Tamil Nadu");
        state.add("Telangana");
        state.add("Tripura");
        state.add("Uttar Pradesh");
        state.add("Uttarkhand");
        state.add("West Bengal");
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,state);
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner_state.setAdapter(dataAdapter);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v)
            {
                city=spinner_state.getSelectedItem().toString();
                session.setState(city);

                rbId=rg.getCheckedRadioButtonId();
                rb=(RadioButton)findViewById(rbId);
                Toast.makeText(getApplicationContext(),"True",Toast.LENGTH_LONG).show();
                /*Intent i = new Intent(MainActivity.this, JobActivity.class);
                i.putExtra("data", rb.getText());
                startActivity(i);*/
            }
        });
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id)
    {
        //city = parent.getItemAtPosition(position).toString();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent)
    {

    }
}

package com.example.jay.jobfinder;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.content.pm.PackageInstaller;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Locale;

public class JobActivity extends AppCompatActivity
{
    Activity context;

    HttpPost httppost;

    StringBuffer buffer;

    HttpResponse response;

    HttpClient httpclient;

    ProgressDialog pd;

    jobAdapter adapter;

    ListView listJob;
    ArrayList<job> records;
    private session session;
    String s,states;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_job);
        session = new session(getApplicationContext());
        states=session.getState();
        Intent i = getIntent();
        i.getExtras();
        s = i.getStringExtra("data");
        Toast.makeText(getApplicationContext(),s,Toast.LENGTH_LONG).show();
        context=this;
        records=new ArrayList<job>();
        listJob=(ListView)findViewById(R.id.lvJob);
        adapter=new jobAdapter(context,R.layout.list_job,R.id.tvState1,records);
        listJob.setAdapter(adapter);
        BackTask bt=new BackTask();
        bt.execute();
    }
    public void onStart(){
        super.onStart();

        //execute background task
        BackTask bt=new BackTask();
        bt.execute();
    }
    private class BackTask extends AsyncTask<Void,Void,Void>
    {
        protected void onPreExecute()
        {
            super.onPreExecute();
            pd = new ProgressDialog(context);
            //pd.setTitle("Retrieving data");
            //pd.setMessage("Please wait.");
            pd.setCancelable(true);
            pd.setIndeterminate(true);
            //pd.show();
        }
        protected Void doInBackground(Void...params)
        {
            InputStream is=null;
            String result="";
            try
            {
                httpclient=new DefaultHttpClient();
                httppost= new HttpPost("http://10.0.2.2/JobFinder/Android/FetchJob2.php");
                response=httpclient.execute(httppost);
                HttpEntity entity = response.getEntity();
                // Get our response as a String.
                is = entity.getContent();
            }
            catch(Exception e)
            {
                if(pd!=null)
                    pd.dismiss(); //close the dialog if error occurs
                Log.e("ERROR", e.getMessage());
            }
            //convert response to string
            try
            {
                BufferedReader reader = new BufferedReader(new InputStreamReader(is,"utf-8"),8);
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null)
                {
                    sb.append(line+"\n");
                }
                is.close();
                result=sb.toString();
            }
            catch(Exception e)
            {
                Log.e("ERROR", "Error converting result "+e.toString());
            }
            //parse json data

            try{

                // Remove unexpected characters that might be added to beginning of the string
                result=result.substring(result.indexOf("["));
                JSONArray jArray =new JSONArray(result);
                for(int i=0;i<jArray.length();i++)
                {
                    JSONObject json_data =jArray.getJSONObject(i);

                    job p=new job();

                    p.setState(json_data.getString("state"));

                    p.setCat(json_data.getString("category"));

                    p.setPost(json_data.getString("post"));

                    p.setVacancy(json_data.getInt("vacancy"));

                    records.add(p);
                }
            }
            catch(Exception e)
            {

                Log.e("ERROR", "Error pasting data "+e.toString());
            }
            return null;
        }
        protected void onPostExecute(Void result)
        {
            session.setState(s);
            if(pd!=null) pd.dismiss(); //close dialog

            Log.e("size", records.size() + "");

            adapter.notifyDataSetChanged(); //notify the ListView to get new records
        }
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        return super.onOptionsItemSelected(item);
    }
}

package com.example.jay.jobfinder;

/**
 * Created by Jay on 7/13/2017.
 */
import android.content.Context;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;

public class session
{

    private SharedPreferences prefs;

    public session(Context cntx)
    {
        // TODO Auto-generated constructor stub
        prefs = PreferenceManager.getDefaultSharedPreferences(cntx);
    }

    public void setState(String state)
    {
        prefs.edit().putString("state", state).commit();
        // prefsCommit();
    }

    public String getState()
    {
        String state = prefs.getString("state","");
        return state;
    }
}

package com.example.jay.jobfinder;
/**
 * Created by Jay on 7/13/2017.
 */
import java.util.ArrayList;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Filter;
import android.widget.TextView;

public class jobAdapter extends ArrayAdapter<job>
{
    int groupid;

    private ArrayList<job> originalList;
    private ArrayList<job> countryList;
    private JobFilter filter;
    Context context;

    public jobAdapter(Context context, int vg, int id, ArrayList<job> countryList)
    {
        super(context, vg, id, countryList);
        this.context = context;
        groupid = vg;
        this.countryList = countryList;
        this.countryList.addAll(countryList);
        this.originalList = countryList;
        this.originalList.addAll(countryList);
    }
    @Override
    public Filter getFilter()
    {
        if (filter == null)
        {
            filter  = new JobFilter();
        }
        return filter;
    }

    public View getView(int position, View convertView, ViewGroup parent) {

        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        View itemView = inflater.inflate(groupid, parent, false);

        TextView State = (TextView) itemView.findViewById(R.id.tvState1);
        State.setText(countryList.get(position).getState());

        TextView Category = (TextView) itemView.findViewById(R.id.tvCat1);
        Category.setText(countryList.get(position).getCat() + "");

        TextView Post = (TextView) itemView.findViewById(R.id.tvPost1);
        Post.setText(countryList.get(position).getPost() + "");

        TextView Vacancy = (TextView) itemView.findViewById(R.id.tvVac1);
        Vacancy.setText(countryList.get(position).getVacancy() + "");

        return itemView;

    }
    private class JobFilter extends Filter
    {
        @Override
        protected Filter.FilterResults performFiltering(CharSequence constraint)
        {
            constraint = constraint.toString().toLowerCase();
            FilterResults result = new FilterResults();
            if(constraint != null && constraint.toString().length() > 0)
            {
                ArrayList<job> filteredItems = new ArrayList<job>();
                for(int i = 0, l = originalList.size(); i < l; i++)
                {
                    job area = originalList.get(i);
                    if(area.toString().toLowerCase().contains(constraint))
                        filteredItems.add(area);
                }
                result.count = filteredItems.size();
                result.values = filteredItems;
            }
            else
            {
                synchronized(this)
                {
                    result.values = originalList;
                    result.count = originalList.size();
                }
            }
            return result;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint,FilterResults results)
        {

            countryList = (ArrayList<job>)results.values;
            notifyDataSetChanged();
            clear();
            for(int i = 0, l = countryList.size(); i < l; i++)
                add(countryList.get(i));
            notifyDataSetInvalidated();
        }
    }
}

package com.example.jay.jobfinder;

/**
 * Created by Jay on 7/13/2017.
 */

public class job
{
    String state,cat,post;
    int vacancy;
    public String getState()
    {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getCat()
    {
        return cat;
    }

    public void setCat(String cat) {
        this.cat = cat;
    }

    public String getPost()
    {
        return post;
    }

    public void setPost(String post) {
        this.post = post;
    }

    public int getVacancy()
    {
        return vacancy;
    }

    public void setVacancy(int vacancy)
    {
        this.vacancy=vacancy;
    }

    public String toString()
    {
        return  state + "," + cat + ","+ post+","+vacancy;
    }
}

FetchJob2.php

<?php
session_start();
$city=$_POST['states'];
$con = mysql_connect("localhost","root");
mysql_select_db("jobs", $con);
$sql = "select state,category,post,vacancy from main_tbl where state='".$city."'";
// Execute query
$result = mysql_query($sql,$con);
// Loop through each records 
while($row = mysql_fetch_assoc($result))
{
$output[]=$row;
}
print(json_encode($output));
?>

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发生了什么事？如果它崩溃了，请添加您的日志，您的问题不清楚谢谢，但我的问题解决了