I'm trying to get the basics of an Android app that sends and receives data from a MySQL server (my implementation will have nothing to do with this learning example). Here's the code so far:
package com.davekelley.polling;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.ParseException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ActionBar;
import android.app.Activity;
import android.app.ListActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;
public class Chart extends Activity {
JSONArray jArray;
String result = null;
InputStream is = null;
StringBuilder sb=null;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.chartfragment);
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://www.davidjkelley.net/city.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection "+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
sb = new StringBuilder();
sb.append(reader.readLine() + "
");
String line="0";
while ((line = reader.readLine()) != null) {
sb.append(line + "
");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
//paring data
int ct_id;
String ct_name;
try{
jArray = new JSONArray(result);
JSONObject json_data=null;
for(int i=0;i<jArray.length();i++){
json_data = jArray.getJSONObject(i);
ct_id=json_data.getInt("CITY_ID");
ct_name=json_data.getString("CITY_NAME");
}
}
catch(JSONException e1){
Toast.makeText(getBaseContext(), "No City Found" ,Toast.LENGTH_LONG).show();
} catch (ParseException e1) {
e1.printStackTrace();
}
}
}
And here's the code for the XML file 'chartfragment':
<?xml version="1.0" encoding="utf-8"?>
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<!-- <LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/chartTitleTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge" android:gravity="center"/>
-->
</ListView>
And here are the LogCat problems I'm encountering:
03-26 20:34:13.782: E/log_tag(1025): Error in http connection android.os.NetworkOnMainThreadException
03-26 20:34:13.802: E/log_tag(1025): Error converting result java.lang.NullPointerException
03-26 20:34:13.802: D/AndroidRuntime(1025): Shutting down VM
03-26 20:34:13.802: W/dalvikvm(1025): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
03-26 20:34:13.832: E/AndroidRuntime(1025): FATAL EXCEPTION: main
03-26 20:34:13.832: E/AndroidRuntime(1025): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.davekelley.polling/com.davekelley.polling.Chart}: java.lang.NullPointerException
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.ActivityThread.access$600(ActivityThread.java:123)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.os.Handler.dispatchMessage(Handler.java:99)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.os.Looper.loop(Looper.java:137)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.ActivityThread.main(ActivityThread.java:4424)
03-26 20:34:13.832: E/AndroidRuntime(1025): at java.lang.reflect.Method.invokeNative(Native Method)
03-26 20:34:13.832: E/AndroidRuntime(1025): at java.lang.reflect.Method.invoke(Method.java:511)
03-26 20:34:13.832: E/AndroidRuntime(1025): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-26 20:34:13.832: E/AndroidRuntime(1025): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-26 20:34:13.832: E/AndroidRuntime(1025): at dalvik.system.NativeStart.main(Native Method)
03-26 20:34:13.832: E/AndroidRuntime(1025): Caused by: java.lang.NullPointerException
03-26 20:34:13.832: E/AndroidRuntime(1025): at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
03-26 20:34:13.832: E/AndroidRuntime(1025): at org.json.JSONTokener.nextValue(JSONTokener.java:94)
03-26 20:34:13.832: E/AndroidRuntime(1025): at org.json.JSONArray.<init>(JSONArray.java:87)
03-26 20:34:13.832: E/AndroidRuntime(1025): at org.json.JSONArray.<init>(JSONArray.java:103)
03-26 20:34:13.832: E/AndroidRuntime(1025): at com.davekelley.polling.Chart.onCreate(Chart.java:68)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.Activity.performCreate(Activity.java:4465)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
03-26 20:34:13.832: E/AndroidRuntime(1025): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
03-26 20:34:13.832: E/AndroidRuntime(1025): ... 11 more
So obviously the network connection on main thread problem means I need to move this into an Asynctask, right? But with such a bevy of errors, I wonder if I am missing something else, that's obvious? I eventually want to be able to register user/passwords onto a database, then get queries and send responses, so this is just a warm up basically. If you goto http://www.davidjkelley.net/city.php you can see that the database is indeed properly responding to the query PHP file that I have linked inside the Android code, so that's not the problem.
Edit~ I should note that my Activity previously extended list Activity, following this tutorial: http://blog.sptechnolab.com/2011/02/10/android/android-connecting-to-mysql-using-php/ which is why my XML is just a ListView at the moment, because that helped clear up an error that said I needed a ListView component with the id 'list'.
Edit~ My php code:
<?php
mysql_connect("127.0.0.1","***","***");
mysql_select_db("***");
$sql=mysql_query("select * from CITY where CITY_NAME like 'A%'");
while($row=mysql_fetch_assoc($sql))
$output[]=$row;
print(json_encode($output));
mysql_close();
?>
Obviously the sets of stars are the correct information, as when you visited the link posted above, the SQL readout appears properly.
