SQLite

Question

'da JSON depolamak JSON verilerini sqlite'ye depolamakla ilgili sorunlar yaşıyorum. Şu anda uygulamaya çalıştığım kod budur. JSON verileri, yalnızca 40 satırda özellikle büyük değildir.

ana faaliyettir:

public class DatabaseActivity extends Activity { 
/** Called when the activity is first created. */ 

public DBAdapter 
DBAdapter =new DBAdapter(this); 

TextView txt; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
setContentView(R.layout.main); 
// Create a crude view - this should really be set via the layout resources 
// but since its an example saves declaring them in the XML. 
LinearLayout rootLayout = new LinearLayout(getApplicationContext()); 
txt = new TextView(getApplicationContext()); 
rootLayout.addView(txt); 
setContentView(rootLayout); 

// Set the text and call the connect function. 
txt.setText("Connecting..."); 
//call the method to run the data retreival 
txt.setText(getServerData(KEY_13)); 

} 

public static final String KEY_13 = "http://xxx.xxx.xxx/api/train.php"; 


private String getServerData(String returnString) { 

InputStream is = null; 

String result = ""; 
//the train line to send 
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); 
nameValuePairs.add(new BasicNameValuePair("code","A")); 

//http post 
try{ 
     HttpClient httpclient = new DefaultHttpClient(); 
     HttpPost httppost = new HttpPost(KEY_13); 
     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); 
     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("log_tag", "Error converting result "+e.toString()); 
} 

//parse json data 
try{ 
     JSONArray jArray = new JSONArray(result); 
     for(int i=0;i<jArray.length();i++){ 
       JSONObject json_data = jArray.getJSONObject(i); 
       DBAdapter.insertTrain(json_data.getString("id"), 
            json_data.getString("code"), 
            json_data.getString("station"), 
            json_data.getString("platform"), 
            json_data.getString("timetillstation"), 
            json_data.getString("traindestination"), 

       //Get an output to the screen 
       returnString += "\n\t" + jArray.getJSONObject(i); 
     } 
}catch(JSONException e){ 
     Log.e("log_tag", "Error parsing data "+e.toString()); 
} 
return returnString; 
}  

} 

adaptör geçerli:

public class DBAdapter{ 
public static final String KEY_ID = "id"; 
public static final String KEY_Code = "code"; 
public static final String KEY_Station = "station"; 
public static final String KEY_Platform = "platform"; 
public static final String KEY_TimeTillStation = "timetillstation"; 
public static final String KEY_TrainDestination = "traindestination"; 
private static final String TAG = "DBAdapter"; 

private static final String DATABASE_NAME = "trains"; 
private static final String DATABASE_TABLE = "Mekerel"; 
private static final int DATABASE_VERSION = 1; 
private static final String DATABASE_CREATE = 
    "create table titles (id integer primary key, " 
    + "code text not null," 
    + "station text not null," 
    + "platform text not null," 
    + "timetillstation text not null," 
    + "traindestination text not null);"; 

private final Context context; 

private DatabaseHelper DBHelper; 
private SQLiteDatabase db; 
public DBAdapter(Context ctx) 
    { 
     this.context = ctx; 
     DBHelper = new DatabaseHelper(context); 
     this.db=DBHelper.getWritableDatabase(); 
    } 

private static class DatabaseHelper extends SQLiteOpenHelper 
{ 
    DatabaseHelper(Context context) 
    { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 
    @Override 
    public void onCreate(SQLiteDatabase db) 
    { 
     db.execSQL(DATABASE_CREATE);  } 
    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, 
    int newVersion) 
    { 
     Log.w(TAG, "Upgrading database from version " + oldVersion 
       + " to " 
       + newVersion + ", which will destroy all old data"); 
     db.execSQL("DROP TABLE IF EXISTS titles"); 
     onCreate(db); 
    } 
}  

//---opens the database--- 
public DBAdapter open() throws SQLException 
{ 
    db = DBHelper.getWritableDatabase(); 
    return this; 
} 
//---closes the database---  
public void close() 
{ 
    DBHelper.close(); 
} 

//---insert a train into the database--- 
public long insertTrain(String id, String code, String station, String platform, String timetillstation, String traindestination) 
{ 
    ContentValues initialValues = new ContentValues(); 
    initialValues.put(KEY_ID, id); 
    initialValues.put(KEY_Code, code); 
    initialValues.put(KEY_Station, station); 
    initialValues.put(KEY_Platform, platform); 
    initialValues.put(KEY_TimeTillStation, timetillstation); 
    initialValues.put(KEY_TrainDestination, traindestination); 
    return db.insert(DATABASE_TABLE, null, initialValues); 
} 
//---retrieves all the ttrain--- 
public Cursor getAllTrains() 
{ 
    return db.query(DATABASE_TABLE, new String[] { 
      KEY_ID, 
      KEY_Code, 
      KEY_Station, 
      KEY_Platform, 
      KEY_TimeTillStation, 
      KEY_TrainDestination}, 
      null, 
      null, 
      null, 
      null, 
      null, 
      null); 
} 
//---retrieves a particular train--- 
public Cursor getTrain(long id) throws SQLException 
{ 
    Cursor mCursor = 
      db.query(true, DATABASE_TABLE, new String[] { 
      KEY_ID, 
      KEY_Code, 
      KEY_Station, 
      KEY_Platform, 
      KEY_TimeTillStation, 
      KEY_TrainDestination}, 
     KEY_ID + "=" + id, 
     null, 
     null, 
     null, 
     null, 
     null); 
    if (mCursor != null) { 
     mCursor.moveToFirst(); 
    } 
    return mCursor; 
} 
//---updates a train--- 
public boolean updateTrain(long id, String code, String station, String platform, String timetillstation, String traindestination) 
{ 
    ContentValues args = new ContentValues(); 
    args.put(KEY_Code, code); 
    args.put(KEY_Station, station); 
    args.put(KEY_Platform, platform); 
    args.put(KEY_TimeTillStation, timetillstation); 
    args.put(KEY_TrainDestination, traindestination); 
    return db.update(DATABASE_TABLE, args, 
        KEY_ID + "=" + id, null) > 0; 
} 
} 

Hala sorunlar vardır olarak buradan nereye emin değilim. Günlük kedi aşağıdakileri görüntüler: kodu yanlış tam olarak nereye gittiğini kimse ve nerede yüzden algılamak için uygun günlük kodu yerleştirmek ne bir anlamda ayıklamaya bana yardımcı olabilir Son olarak

12-04 12:43:09.691: E/AndroidRuntime(21334): FATAL EXCEPTION: main 
12-04 12:43:09.691: E/AndroidRuntime(21334): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{ta.dabase/ta.dabase.DatabaseActivity}: java.lang.NullPointerException 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1680) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1784) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.app.ActivityThread.access$1500(ActivityThread.java:123) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:939) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.os.Handler.dispatchMessage(Handler.java:99) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.os.Looper.loop(Looper.java:130) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.app.ActivityThread.main(ActivityThread.java:3835) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at java.lang.reflect.Method.invokeNative(Native Method) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at java.lang.reflect.Method.invoke(Method.java:507) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at dalvik.system.NativeStart.main(Native Method) 
12-04 12:43:09.691: E/AndroidRuntime(21334): Caused by: java.lang.NullPointerException 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:118) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at ta.dabase.DBAdapter.<init>(DBAdapter.java:43) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at ta.dabase.DatabaseActivity.<init>(DatabaseActivity.java:32) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at java.lang.Class.newInstanceImpl(Native Method) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at java.lang.Class.newInstance(Class.java:1409) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 
12-04 12:43:09.691: E/AndroidRuntime(21334): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1672) 
12-04 12:43:09.691: E/AndroidRuntime(21334): ... 11 more 

, merak ediyorum? Teşekkür

Answer 1

bu

1) sizin json verilere göre özelliklerini içeren sınıf oluşturun adımları izlemeniz gerekir Bu sorunu çözmek için.

2) Json verilerinizi sınıfınıza dönüştürün. (Sınıf ile json Eşleme) veritabanına bu sınıfın tüm özelliklerinin

3) depola değerleri (SQLLite) (veritabanı ile sınıfı Eşleme)

**** Çalışmanızı kaydedin ***!

Bitti! Jsoning tadını çıkarın!