php를 이용해서 db를 가져오려고 하는데
안드로이드에서 오류는 발생하지 안아서 바로 실행했는데 아래와 같은 오류가 뜹니다.
05-19 15:03:56.324 2341-2341/com.example.test1 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.test1, PID: 2341
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
at org.json.JSONTokener.nextValue(JSONTokener.java:94)
at org.json.JSONObject.<init>(JSONObject.java:156)
at org.json.JSONObject.<init>(JSONObject.java:173)
at com.example.test1.MainActivity.showList(MainActivity.java:41)
at com.example.test1.MainActivity$1GetDataJSON.onPostExecute(MainActivity.java:88)
at com.example.test1.MainActivity$1GetDataJSON.onPostExecute(MainActivity.java:66)
at android.os.AsyncTask.finish(AsyncTask.java:651)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:668)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
아직 안드로이드 시작한지 얼마 되지 않아서 오류를 잘 못보겠습니다. 구글과 네이버에 검색해봤지만
제가 이해하기가 좀 어려워서 직접 여기서 질문드립니다.
일단 메인 소스는 아래와 같습니다
package com.example.test1;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
public class MainActivity extends AppCompatActivity {
String myJSON;
private static final String TAG_RESULTS="result";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL ="email";
JSONArray peoples = null;
ArrayList<HashMap<String, String>> personList;
ListView list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
list = (ListView) findViewById(R.id.listView);
personList = new ArrayList<HashMap<String,String>>();
getData("http://192.168.0.1/setter.php");
}
protected void showList(){
try {
JSONObject jsonObj = new JSONObject(myJSON);
peoples = jsonObj.getJSONArray(TAG_RESULTS);
for(int i=0;i<peoples.length();i++){
JSONObject c = peoples.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String email = c.getString(TAG_EMAIL);
HashMap<String,String> persons = new HashMap<String,String>();
persons.put(TAG_ID,id);
persons.put(TAG_NAME,name);
persons.put(TAG_EMAIL,email);
personList.add(persons);
}
ListAdapter adapter = new SimpleAdapter(
MainActivity.this, personList, R.layout.list_item,
new String[]{TAG_ID,TAG_NAME,TAG_EMAIL},
new int[]{R.id.id, R.id.name, R.id.email}
);
list.setAdapter(adapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
public void getData(String url){
class GetDataJSON extends AsyncTask<String, Void, String>{
@Override
protected String doInBackground(String... params) {
String uri = params[0];
BufferedReader bufferedReader = null;
try {
URL url = new URL(uri);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String json;
while((json = bufferedReader.readLine())!= null){
sb.append(json+"\n");
}
return sb.toString().trim();
}catch(Exception e){
return null;
}
}
@Override
protected void onPostExecute(String result){
myJSON=result;
showList();
}
}
GetDataJSON g = new GetDataJSON();
g.execute(url);
}
}
