Why can't I use Resources.getSystem() without a Runtime error?

问题

public class BobDatabase extends SQLiteOpenHelper{
private static final String DATABASE_NAME = "bob.db";
private static final int DATABASE_VERSION = 1;
public static final String DEFAULT_PROFILE = "default_profile";

public BobDatabase(Context context) 
{
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase database) 
{
    createProfileTable(database);
    createTimeTable(database);
    createEventTable(database);
    createLocationTable(database);
}

/**
 * Creates a table for Profile objects, executes the string create_profile_table_sql
 * contained within strings.xml
 * @param database
 */
public void createProfileTable(SQLiteDatabase database)
{
    database.execSQL(Resources.getSystem().getString(R.string.create_profile_table_sql));
}}

I get this error

01-14 12:20:57.591: E/AndroidRuntime(1825): Caused by: android.content.res.Resources$NotFoundException: String resource ID #0x7f040003

The code that causes the error is the single line inside createProfileTable specifically, Resources.getSystem().getString(R.string.create_profile_table_sql) if I use a class variable to hold a Context and do context.getString(R.string.create_profile_table_sql) I don't get any errors but I don't want to do that because I want to avoid memory leaks and according to what I know this should work. Any idea what's happening?

回答1:

According to Android documentation, Resources.getSystem() only provides system-level resources, not application-level ones (like the resources inside your strings.xml file).

http://developer.android.com/reference/android/content/res/Resources.html#getSystem()

Try using the application's context if you really want to retrieve your strings this way, or take my suggestion in the comment to your question.

回答2:

Using Resources.getSystem().getWhatEver() you can only access system-wide resources (you get the error because there is not system-wide resource with your ID). Since resource ID are not unique across applications you need provide the application when accessing a resource. In Android this is done using Context. So if you want to access some resource you need to use it like this