java.lang.StringIndexOutOfBoundsException：指数= 0长度= 0获取SQLite数据库 [英] java.lang.StringIndexOutOfBoundsException: index=0 length=0 in get sqlite database

问题描述

我想这个code。打开一个可写的SQLite数据库...

I am trying to open a writeable SQLite database with this code...

public DataAdapterForServieClass open() throws SQLException {
    db = DBHelper.getWritableDatabase();
    return this;
}

不过我收到以下错误 DB = DBHelper.getWritableDatabase（）; 行...

06-10 11:58:13.995: ERROR/AndroidRuntime(548): FATAL EXCEPTION: main
06-10 11:58:13.995: ERROR/AndroidRuntime(548): java.lang.StringIndexOutOfBoundsException: index=0 length=0
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.app.ContextImpl.validateFilePath(ContextImpl.java:1518)
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.app.ContextImpl.openOrCreateDatabase(ContextImpl.java:725)
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:221)
06-10 11:58:13.995: ERROR/AndroidRuntime(548):     at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:149)

这是我的 DBHelper 类的code ...

This is the code of my DBHelper class...

static class DatabaseHelper extends SQLiteOpenHelper {
    DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    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);
    }

    public void onCreate(SQLiteDatabase arg0) {
        // TODO Auto-generated method stub
    }
}   

可能有人请帮助我。

Could someone please help me.

推荐答案

当你调用 getWritableDatabase（）首次，它会调用下面的方法，根据在的Andr​​oid文档 ...

When you call getWritableDatabase() for the first time, it will call the following methods, according to the Android Documentation...

onCreate(SQLiteDatabase)
onUpgrade(SQLiteDatabase, int, int)
onOpen(SQLiteDatabase)

您没有任何code在的onCreate（）方法 - 你需要做的东西在这里之前，将工作，像这样的。 ..

You don't have any code in your onCreate() method - you'll need to do something here before it will work, such as this...

public void onCreate(SQLiteDatabase database) {
    database.openOrCreateDatabase("/come/example/mydatabase",null);
}

看那 checkDataBase（）法在的链接您发布它调用的openDatabase（） - 这样做同样的事情，而且是重要的一块code，你就错过。您需要创建数据库之前，你可以用它做任何事情。

Look at the checkDataBase() method in the link you posted where it calls openDatabase() - this does the same thing, and is the important piece of code that you're missing. You need to create the database before you can do anything with it.

另外，还要确保在某处的code，你正在创建你的DBHelper实例，以便它调用超（）方法。像这样...

Also make sure that somewhere in your code you are creating your DBHelper instance, so that it calls the super() method. Like this...

DBHelper helper = new DatabaseHelper(context);

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