Android：Sqlite数据库错误

-6

我正在编写数据库的代码以获取包含三个字段的活动数据，即即Truck_id,employee_id和password。Android：Sqlite数据库错误

我收到一些错误;下面是我的代码：请帮助我，因为我是新来的android：

public class DataBaseHelper extends SQLiteOpenHelper { 

// default system path of your application database. 
// private static String DB_PATH = "/data/data/com.tanzanite.operasoft/databases/"; 

private static String DB_PATH = "/sdcard/"; 

private static String DB_NAME = "snowman"; 

private static SQLiteDatabase myDataBase; 

private Context myContext; 

private DataBaseHelper dbHelper; 


/** 
* Constructor Takes and keeps a reference of the passed context in order to 
* access to the application assets and resources. 
* 
* @param context 
*/ 
public DataBaseHelper(Context context) { 

    super(context, DB_NAME, null, 1); 

    this.myContext = context; 
} 

public void TestAdapter(Context context) 
{ 
    this.myContext= context; 
} 

public static final String TABLE_NAME = "Login"; 
private static final int DATABASE_VERSION= 2; 

private static final String DATABASE_NAME="snowman"; 


public static final String COLUMN_ID = "_id"; 
public static final String COLUMN_NAME = "employee_id"; 
public static final String COLUMN_TRUCKID = "truck_id"; 


public static final int NAME_COLUMN=1; 
public static final String KEY_CREATION_DATE="creation_date"; 
public static final String KEY_TASK="task"; 


/** 
* Creates a empty database on the system and rewrites it with your own 
* database. 
* */ 

private static final String DATABASE_CREATE = "create table " 
     + TABLE_NAME + "(" + COLUMN_ID + " integer primary key autoincrement, " 
          + COLUMN_TRUCKID+ " text not null, " 
          + COLUMN_NAME+ " text not null,)"; 


public void createDataBase() throws IOException { 

    boolean dbExist = checkDataBase(); 

    if (dbExist) { 
     // do nothing - database already exist 
    } else { 

     // By calling this method and empty database will be created into 
     // the default system path 
     // of your application so we are gonna be able to overwrite that 
     // database with our database. 
     //this.getReadableDatabase(); 

     try { 

      copyDataBase(); 

     } catch (IOException e) { 

      throw new Error("Error copying database"); 

     } 
    } 

} 

public DataBaseHelper open() throws SQLException 
{ 
     //myDataBase = dbHelper.getWritableDatabase(); 
     return this; 
} 


/** 
* Check if the database already exist to avoid re-copying the file each 
* time you open the application. 
* 
* @return true if it exists, false if it doesn't 
*/ 
private boolean checkDataBase() { 

SQLiteDatabase checkDB = null; 

    try { 
     String myPath = DB_PATH + DB_NAME; 
     checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 

    } catch (SQLiteException e) { 
     String myPath = DB_PATH + DB_NAME; 
     File dbfile = new File(myPath); 
     SQLiteDatabase.openOrCreateDatabase(dbfile, null); 

     //throw new Error("Database does't exist yet."); 

    } 

    if (checkDB != null) { 

     checkDB.close(); 

    } 

    return checkDB != null ? true : false; 
} 

/** 
* Copies your database from your local assets-folder to the just created 
* empty database in the system folder, from where it can be accessed and 
* handled. This is done by transfering bytestream. 
* */ 
private void copyDataBase() throws IOException { 

    // Open your local db as the input stream 
    InputStream myInput = myContext.getAssets().open(DB_NAME); 

    // Path to the just created empty db 
    String outFileName = DB_PATH + DB_NAME; 

    // Open the empty db as the output stream 
    OutputStream myOutput = new FileOutputStream(outFileName); 

    // transfer bytes from the inputfile to the outputfile 
    byte[] buffer = new byte[128]; 
    int length; 
    while ((length = myInput.read(buffer)) > 0) { 
     myOutput.write(buffer, 0, length); 
    } 

    // Close the streams 
    myOutput.flush(); 
    myOutput.close(); 
    myInput.close(); 

} 

public void openDataBase() throws SQLException { 

    // Open the database 
    String myPath = DB_PATH + DB_NAME; 
    myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE); 
    return; 

} 

public String logindetails() 
{ 
    open(); 
    Cursor c=myDataBase.query(TABLE_NAME, 
      new String[]{COLUMN_NAME, 
          COLUMN_TRUCKID, 

          },null, null, null, null, null); 
    String b=""; 

    c.close(); 
    myDataBase.close(); 
    return b; 
} 

public void insert(String a, String b){ 

    ContentValues vals = new ContentValues(); 
    vals.put(COLUMN_TRUCKID, "CM-3456"); 
    vals.put(COLUMN_NAME,"Sachin"); 
    //vals.put(KEY_PIN, "12345"); 

    vals.put(COLUMN_TRUCKID, "HR-6788"); 
    vals.put(COLUMN_NAME,"Sameer"); 
    //vals.put(KEY_PIN, "54321"); 

    vals.put(COLUMN_ID, "AM-6123"); 
    vals.put(COLUMN_NAME,"Sahu"); 
    //vals.put(KEY_PIN, "3452"); 


    myDataBase.close(); 


} 

public Cursor fetchdata() 
{ 
    open(); 
    Cursor c=myDataBase.query(TABLE_NAME, 
     new String[]{COLUMN_NAME, 
      COLUMN_TRUCKID, 

         },null, null, null, null, null); 
    c.moveToLast(); 
    myDataBase.close(); 
    return c; 
} 


public static SQLiteDatabase getDataBase() { 
    return myDataBase; 

} 

@Override 
public synchronized void close() { 

    if (myDataBase != null) 
     myDataBase.close(); 

    super.close(); 

} 

@Override 
public void onCreate(SQLiteDatabase db) { 
    try{ 

    db.execSQL(DATABASE_CREATE); 
    }catch(Exception e) 
    { 
     Log.v("Press_Data","exception in table created"); 
    }

}

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 

}

的错误是..

06-14 18:22:27.233: D/dalvikvm(25087): GC_CONCURRENT freed 757K, 48% free 3547K/6727K, external 1625K/2137K, paused 4ms+4ms 
06-14 18:22:27.393: I/net.osmand(25087): BaseOsmandRender Init render default for 738 ms 
06-14 18:22:27.523: D/dalvikvm(25087): GC_EXTERNAL_ALLOC freed 123K, 46% free 3635K/6727K, external 1625K/2137K, paused 62ms 
06-14 18:22:27.633: D/AndroidRuntime(25087): Shutting down VM 
06-14 18:22:27.633: W/dalvikvm(25087): threadid=1: thread exiting with uncaught exception (group=0x40015560) 
06-14 18:22:27.663: E/AndroidRuntime(25087): FATAL EXCEPTION: main 
06-14 18:22:27.663: E/AndroidRuntime(25087): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tanzanite.operasoft/com.tanzanite.operasoft.activity.Sw_LoginScreenActivity}: java.lang.NullPointerException 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.os.Handler.dispatchMessage(Handler.java:99) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.os.Looper.loop(Looper.java:130) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.app.ActivityThread.main(ActivityThread.java:3683) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at java.lang.reflect.Method.invokeNative(Native Method) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at java.lang.reflect.Method.invoke(Method.java:507) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at dalvik.system.NativeStart.main(Native Method) 
06-14 18:22:27.663: E/AndroidRuntime(25087): Caused by: java.lang.NullPointerException 
06-14 18:22:27.663: E/AndroidRuntime(25087): at com.tanzanite.operasoft.database.DataBaseHelper.fetchdata(DataBaseHelper.java:222) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at com.tanzanite.operasoft.activity.Sw_LoginScreenActivity.onCreate(Sw_LoginScreenActivity.java:52) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
06-14 18:22:27.663: E/AndroidRuntime(25087): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 
06-14 18:22:27.663: E/AndroidRuntime(25087): ... 11 more 
06-14 18:28:37.603: D/dalvikvm(26440): GC_CONCURRENT freed 757K, 48% free 3541K/6727K, external 1625K/2137K, paused 3ms+3ms 
06-14 18:28:37.773: I/net.osmand(26440): BaseOsmandRender Init render default for 611 ms 
06-14 18:28:37.873: D/dalvikvm(26440): GC_EXTERNAL_ALLOC freed 122K, 46% free 3633K/6727K, external 1625K/2137K, paused 51ms 
06-14 18:28:38.013: D/AndroidRuntime(26440): Shutting down VM 
06-14 18:28:38.013: W/dalvikvm(26440): threadid=1: thread exiting with uncaught exception (group=0x40015560) 
06-14 18:28:38.033: E/AndroidRuntime(26440): FATAL EXCEPTION: main 
06-14 18:28:38.033: E/AndroidRuntime(26440): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tanzanite.operasoft/com.tanzanite.operasoft.activity.Sw_LoginScreenActivity}: java.lang.NullPointerException 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.os.Handler.dispatchMessage(Handler.java:99) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.os.Looper.loop(Looper.java:130) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.app.ActivityThread.main(ActivityThread.java:3683) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at java.lang.reflect.Method.invokeNative(Native Method) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at java.lang.reflect.Method.invoke(Method.java:507) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at dalvik.system.NativeStart.main(Native Method) 
06-14 18:28:38.033: E/AndroidRuntime(26440): Caused by: java.lang.NullPointerException 
06-14 18:28:38.033: E/AndroidRuntime(26440): at com.tanzanite.operasoft.database.DataBaseHelper.fetchdata(DataBaseHelper.java:222) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at com.tanzanite.operasoft.activity.Sw_LoginScreenActivity.onCreate(Sw_LoginScreenActivity.java:52) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
06-14 18:28:38.033: E/AndroidRuntime(26440): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 
06-14 18:28:38.033: E/AndroidRuntime(26440): ... 11 more 
06-14 18:40:55.423: D/dalvikvm(29844): GC_CONCURRENT freed 759K, 48% free 3553K/6727K, external 1625K/2137K, paused 5ms+3ms 
06-14 18:40:55.633: I/net.osmand(29844): BaseOsmandRender Init render default for 841 ms 
06-14 18:40:55.773: D/dalvikvm(29844): GC_EXTERNAL_ALLOC freed 122K, 46% free 3633K/6727K, external 1625K/2137K, paused 58ms 
06-14 18:40:55.913: D/AndroidRuntime(29844): Shutting down VM 
06-14 18:40:55.913: W/dalvikvm(29844): threadid=1: thread exiting with uncaught exception (group=0x40015560) 
06-14 18:40:55.943: E/AndroidRuntime(29844): FATAL EXCEPTION: main 
06-14 18:40:55.943: E/AndroidRuntime(29844): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tanzanite.operasoft/com.tanzanite.operasoft.activity.Sw_LoginScreenActivity}: java.lang.NullPointerException 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.os.Handler.dispatchMessage(Handler.java:99) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.os.Looper.loop(Looper.java:130) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.app.ActivityThread.main(ActivityThread.java:3683) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at java.lang.reflect.Method.invokeNative(Native Method) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at java.lang.reflect.Method.invoke(Method.java:507) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at dalvik.system.NativeStart.main(Native Method) 
06-14 18:40:55.943: E/AndroidRuntime(29844): Caused by: java.lang.NullPointerException 
06-14 18:40:55.943: E/AndroidRuntime(29844): at com.tanzanite.operasoft.database.DataBaseHelper.fetchdata(DataBaseHelper.java:223) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at com.tanzanite.operasoft.activity.Sw_LoginScreenActivity.onCreate(Sw_LoginScreenActivity.java:52) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
06-14 18:40:55.943: E/AndroidRuntime(29844): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 
06-14 18:40:55.943: E/AndroidRuntime(29844): ... 11 more 
06-14 19:12:06.293: D/dalvikvm(5930): GC_CONCURRENT freed 763K, 48% free 3549K/6727K, external 1625K/2137K, paused 4ms+5ms 
06-14 19:12:06.443: I/net.osmand(5930): BaseOsmandRender Init render default for 689 ms 
06-14 19:12:06.553: D/dalvikvm(5930): GC_EXTERNAL_ALLOC freed 120K, 47% free 3632K/6727K, external 1625K/2137K, paused 64ms 
06-14 19:12:06.703: D/AndroidRuntime(5930): Shutting down VM 
06-14 19:12:06.703: W/dalvikvm(5930): threadid=1: thread exiting with uncaught exception (group=0x40015560) 
06-14 19:12:06.723: E/AndroidRuntime(5930): FATAL EXCEPTION: main 
06-14 19:12:06.723: E/AndroidRuntime(5930): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.tanzanite.operasoft/com.tanzanite.operasoft.activity.Sw_LoginScreenActivity}: java.lang.NullPointerException 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.os.Handler.dispatchMessage(Handler.java:99) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.os.Looper.loop(Looper.java:130) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.app.ActivityThread.main(ActivityThread.java:3683) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at java.lang.reflect.Method.invokeNative(Native Method) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at java.lang.reflect.Method.invoke(Method.java:507) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at dalvik.system.NativeStart.main(Native Method) 
06-14 19:12:06.723: E/AndroidRuntime(5930): Caused by: java.lang.NullPointerException 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at com.tanzanite.operasoft.database.DataBaseHelper.fetchdata(DataBaseHelper.java:224) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at com.tanzanite.operasoft.activity.Sw_LoginScreenActivity.onCreate(Sw_LoginScreenActivity.java:49) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611) 
06-14 19:12:06.723: E/AndroidRuntime(5930):  ... 11 more

来源

2012-06-14 user1423111

那么，什么是错误的？ –

@GrahamBorland你看不到它们吗？我不得不滚动页面：D – pawelzieba

@ user1423111我可以告诉你为什么你会得到一个错误，但是我会建议你学习一些关于在android中使用数据库的知识。 – Luksprog

从您登录我看到

Caused by: java.lang.NullPointerException 
06-14 19:12:06.723: E/AndroidRuntime(5930): at com.tanzanite.operasoft.database.DataBaseHelper.fetchdata(DataBaseHelper.java:224) 
06-14 19:12:06.723: E/AndroidRuntime(5930): at com.tanzanite.operasoft.activity.Sw_LoginScreenActivity.onCreate(Sw_LoginScreenActivity.java:49)

所以，你需要使用debuger并设置breackpoints上

Sw_LoginScreenActivity.java - 在线49（我觉得你试图获取数据）

DataBaseHelper.java - 在224 - 有你尝试从MYDATABASE

public Cursor fetchdata() 
{ 
    open(); 
    Cursor c=myDataBase.query(TABLE_NAME, 
     new String[]{COLUMN_NAME, 
      COLUMN_TRUCKID, 

         },null, null, null, null, null); 
    c.moveToLast(); 
    myDataBase.close(); 
    return c; 
}

获取数据

但是，在open（）方法

public DataBaseHelper open() throws SQLException 
{ 
     //myDataBase = dbHelper.getWritableDatabase(); 
     return this; 
}

与创建数据库实例时，您的注释行 - 所以下一行 “光标C = myDataBase.query（TABLE_NAME，” 这不是CORRE ct，因为myDataBase为null。

您没有打开与数据库的连接。

来源

2012-06-14 14:14:54

您的问题根据logcat的就出在这里（空指针异常）：

public String logindetails() 
{ 
    open(); 
    Cursor c=myDataBase.query(TABLE_NAME, new String[]{COLUMN_NAME, COLUMN_TRUCKID, }, 
     null, null, null, null, null); 
    String b=""; 
    c.close(); 
    myDataBase.close(); 
    return b; 
}

我看到几个问题...

首先，你不应该试图打开/在你的db helper的方法中关闭你的数据库。 db应该由另一个实例化dbhelper的类打开和关闭，并使用实例化的类方法打开和关闭db。

其次，你的表列数组列表中有一个额外的逗号。

第三，你似乎无缘无故地调用了一个游标......你明白了，不要对它做任何事情，然后关闭它。

第四，你设置一个空字符串，不做任何事情，然后返回它。

应该看起来更像是这样，我认为：

在你调用类：

private DatabaseHelper mDbHelper; 

mDbHelper = new DatabaseHelper(this); // instantiate the helper 
mDbHelper.openDataBase(); // open the db 
String ldetails = mDbHelper.logindetails(); // get logindetails string from db

在你DatabaseHelper类：

public String logindetails() 
{ 
    String b=""; 
    Cursor c=myDataBase.query(TABLE_NAME, new String[]{COLUMN_NAME, COLUMN_TRUCKID, }, 
     null, null, null, null, null); 
    c.moveToFirst(); 
    // Insert code to get data from cursor to string 
    c.close(); 
    return b; 
}

来源

2012-06-14 14:15:31 Barak

感谢您的帮助..但我仍然收到错误： – user1423111

mDbHelper = new DataBaseHelper（this）; //实例化帮助程序 \t \t mDbHelper.openDataBase（）; //打开db \t \t String ldetails = mDbHelper.logindetails（）; //从db获取logindetails字符串 \t \t \t String [] truck_id = null; \t ArrayAdapter adptTruck = new ArrayAdapter （this，android.R.layout.simple_dropdown_item_1line，truck_id）; \t \t String [] employee_id = null; \t ArrayAdapter adptEMP = new ArrayAdapter （this，android.R.layout.simple_dropdown_item_1line，employee_id）; – user1423111

感谢您的帮助，我解决了我的错误......巴拉克 – user1423111

Android：Sqlite数据库错误

回答

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