java - SQLite 数据库打开时崩溃

Question

我需要在我的 Android 应用程序上使用 SQLite 数据库，但是当我尝试打开它时，它崩溃了，我不知道为什么。在过去的一个小时里我在网上查了一下，但找不到任何帮助。

这是代码:

public class PrivDB {

public static final String KEY_ROWID = "_id";
public static final String KEY_LEVEL = "level";
public static final String KEY_LOCKED = "locked";
public static final String KEY_SEQUENCE = "sequence";
public static final String KEY_TRIES = "tries";

private static final String DATABASE_NAME = "patdb";
private static final String DATABASE_TABLE = "tablename";
private static final int DATABASE_VERSION = 1;

private DbHelper ourHelper;
private Context ourContext;
private SQLiteDatabase ourDatabase;

private static class DbHelper extends SQLiteOpenHelper {

    public DbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase arg0) {
        // TODO Auto-generated method stub
        arg0.execSQL("CREATE TABLE " + DATABASE_TABLE + " ("+
                    KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, "+
                    KEY_LEVEL + " STRING NOT NULL, " +
                    KEY_LOCKED + " INTEGER NOT NULL, " +
                    KEY_SEQUENCE + " INTEGER NOT NULL, "+
                    KEY_TRIES + " INTEGER NOT NULL);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
        // TODO Auto-generated method stub
        arg0.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
        onCreate(arg0);
    }

}

public PrivDB (Context c) {
    ourContext = c;
}

public PrivDB open() throws SQLException {
    ourHelper = new DbHelper(ourContext);
    ourDatabase = ourHelper.getWritableDatabase();
    return this;
}

public void close(){
    ourHelper.close();
}

public long createEntry (String level, int locked, int sequence, int tries){
    ContentValues cv = new ContentValues();
    cv.put(KEY_LEVEL, level);
    cv.put(KEY_LOCKED, locked);
    cv.put(KEY_SEQUENCE, sequence);
    cv.put(KEY_TRIES, tries);
    return ourDatabase.insert(DATABASE_TABLE, null, cv);
}

public String getData() {
    String[] columns = new String[]{KEY_ROWID, KEY_LEVEL, KEY_LOCKED, KEY_SEQUENCE, KEY_TRIES};
    Cursor c = ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
    String result = "";

    int iRow = c.getColumnIndex(KEY_ROWID);
    int iLevel = c.getColumnIndex(KEY_LEVEL);
    int iLocked = c.getColumnIndex(KEY_LOCKED);
    int iSequence = c.getColumnIndex(KEY_SEQUENCE);
    int iTries = c.getColumnIndex(KEY_TRIES);

    for(c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
        result = result + c.getString(iRow) + " " + c.getString(iLevel) + " " + c.getString(iLocked) + " " 
                + c.getString(iSequence) + c.getString(iTries) + "\n";
    }

    return result;
}

public int getLocked(String s) throws SQLException {
    String[] columns = new String[]{KEY_ROWID, KEY_LEVEL, KEY_LOCKED, KEY_SEQUENCE, KEY_TRIES};
    Cursor c = ourDatabase.query(DATABASE_TABLE, columns, KEY_LEVEL + "=" + s, null, null, null, null);
    if(c != null){
        c.moveToFirst();
        int locked = c.getInt(2);
        return locked;
    }
    return (Integer) null;
}

public void updateEntry(String s, int locked, int tries) throws SQLException {
    ContentValues cvUpdate = new ContentValues();
    cvUpdate.put(KEY_LOCKED, locked);
    cvUpdate.put(KEY_TRIES, tries);
    ourDatabase.update(DATABASE_TABLE, cvUpdate, KEY_LEVEL + "=" + s, null);
}

}

以及我如何调用数据库:

public class Stats extends Activity {

TextView tv;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.stats);
    tv = (TextView) findViewById(R.id.tvStats);
    PrivDB info = new PrivDB(this);
    info.open();
    String data = info.getData();
    info.close();
    tv.setText(data);
}

}

当我打开 Stats 类时，应用程序崩溃，但如果我注释掉 info.open() 直到 info.close() 那么它就可以正常工作(但显然什么也没发生)。

更新

这是日志猫输出:

01-09 13:16:32.786: E/AndroidRuntime(517): FATAL EXCEPTION: main
01-09 13:16:32.786: E/AndroidRuntime(517): java.lang.RuntimeException: Unable to start activity     ComponentInfo{com.docime.vamoose.patternz/com.docime.vamoose.patternz.Stats}:     java.lang.StringIndexOutOfBoundsException
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.app.ActivityThread.access$2300(ActivityThread.java:125)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.os.Handler.dispatchMessage(Handler.java:99)
01-09 13:16:32.786: E/AndroidRuntime(517):  at android.os.Looper.loop(Looper.java:123)
01-09 13:16:32.786: E/AndroidRuntime(517):  at android.app.ActivityThread.main(ActivityThread.java:4627)
01-09 13:16:32.786: E/AndroidRuntime(517):  at java.lang.reflect.Method.invokeNative(Native     Method)
01-09 13:16:32.786: E/AndroidRuntime(517):  at java.lang.reflect.Method.invoke(Method.java:521)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
01-09 13:16:32.786: E/AndroidRuntime(517):  at dalvik.system.NativeStart.main(Native Method)
01-09 13:16:32.786: E/AndroidRuntime(517): Caused by: java.lang.StringIndexOutOfBoundsException
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.app.ContextImpl.validateFilePath(ContextImpl.java:1579)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:539)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:203)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:98)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     com.docime.vamoose.patternz.PrivDB.open(PrivDB.java:60)
01-09 13:16:32.786: E/AndroidRuntime(517):  at     com.docime.vamoose.patternz.Stats.onCreate(Stats.java:18)
01-09 13:16:32.786: E/AndroidRuntime(517):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
01-09 13:16:32.786: E/AndroidRuntime(517):  at             android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
01-09 13:16:32.786: E/AndroidRuntime(517):  ... 11 more

Answer 1

您永远不会传递DATABASE_TABLE名称或在代码中分配它。这就是它崩溃的原因。

private static final String DATABASE_TABLE = "TABLE_NAME";

更新:更新您的onCreate()。 SQLite 支持 TEXT instedOf String

@Override
public void onCreate(SQLiteDatabase arg0) {
    // TODO Auto-generated method stub
    arg0.execSQL("CREATE TABLE " + DATABASE_TABLE + " ( "+
                KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, "+
                KEY_LEVEL + " TEXT NOT NULL, " +
                KEY_LOCKED + " INTEGER NOT NULL, " +
                KEY_SEQUENCE + " INTEGER NOT NULL, "+
                KEY_TRIES + " INTEGER NOT NULL);");
 }

另一个重要的事情是传递上下文但不使用静态变量保存它。 你应该像下面这样使用

private static Context ourContext;

public PrivDB (Context c) {
    this.ourContext = c;
}

但最重要的是，当您面临错误/异常

Caused by: java.lang.StringIndexOutOfBoundsException ,

此当字符串的索引值小于零或大于或等于数组大小时抛出

我请求您检查以下内容-java.lang.StringIndexOutOfBoundsException: index=0 length=0 in get sqlite database