Question

首先，我在这里检查了其他类似的线程，但似乎没有什么对我有用。但是，这是我的第一个Android应用程序，所以也许有一些我忽略或不理解的东西。无论如何，这是我的代码。

MyContentProvider.java

 @SuppressWarnings("ConstantConditions")
public class MyContentProvider extends ContentProvider {

private DbHelper dbHelper;

private static final String BASE_PATH_ITEM = "items";
private static final String AUTHORITY = "data.MyContentProvider";
public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/" + BASE_PATH_ITEM);
private static final int ITEM = 100;
private static final int ITEMS = 101;


private static final UriMatcher URI_MATCHER = new UriMatcher(UriMatcher.NO_MATCH);
static {
    URI_MATCHER.addURI(AUTHORITY, BASE_PATH_ITEM, ITEM);
    URI_MATCHER.addURI(AUTHORITY, BASE_PATH_ITEM + "/#", ITEMS);


}

private void checkColumns(String[] projection) {
    if (projection != null) {
        HashSet<String> requestedColumns = new HashSet<String>(Arrays.asList(projection));
        HashSet<String> availableColumns = new HashSet<String>(Arrays.asList(Constants.COLUMNS));
        if (!availableColumns.containsAll(requestedColumns)) {
            throw new IllegalArgumentException("Unknown columns in projection");
        }
    }
}

@Override
public boolean onCreate() {
    dbHelper = new DbHelper(getContext());
    return false;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
    SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
    checkColumns(projection);
    queryBuilder.setTables(Constants.ITEM_TABLE);

    int type = URI_MATCHER.match(uri);
    switch (type){
        case ITEM:
            //there is not to do if the query is for the table
            break;
        case ITEMS:
           queryBuilder.appendWhere(Constants.COLUMN_ID + " = " + uri.getLastPathSegment());
           break;
        default:
            throw new IllegalArgumentException("Unknown URI: " + uri);
    }
    SQLiteDatabase db = dbHelper.getWritableDatabase();
    Cursor cursor = queryBuilder.query(db, projection, selection, selectionArgs, null, null, sortOrder);
    cursor.setNotificationUri(getContext().getContentResolver(), uri);
    return cursor;
}

@Override
public String getType(Uri uri) {
    return null;
}

@Override
public Uri insert(Uri uri, ContentValues values) {
    int type = URI_MATCHER.match(uri);
    SQLiteDatabase db = dbHelper.getWritableDatabase();
    Long id;
    switch (type){
        case ITEMS:
            id = db.insert(Constants.ITEM_TABLE, null, values);
            break;
        default:
            throw new IllegalArgumentException("Unknown URI: " + uri);
    }
    getContext().getContentResolver().notifyChange(uri, null);
    return Uri.parse(BASE_PATH_ITEM + "/" + id);
}


@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
    int type = URI_MATCHER.match(uri);
    SQLiteDatabase db = dbHelper.getWritableDatabase();
    int rowsDeleted;
    switch (type) {
        case ITEM:
            rowsDeleted = db.delete(Constants.ITEM_TABLE, selection, selectionArgs);
            break;

        case ITEMS:
            String id = uri.getLastPathSegment();
            if (TextUtils.isEmpty(selection)) {
                rowsDeleted = db.delete(Constants.ITEM_TABLE, Constants.COLUMN_ID + "=" + id, null);
            } else {
                rowsDeleted = db.delete(Constants.ITEM_TABLE, Constants.COLUMN_ID + "=" + id + " and " + selection, selectionArgs);
            }
            break;

        default:
            throw new IllegalArgumentException("Unknown URI: " + uri);
    }
    getContext().getContentResolver().notifyChange(uri, null);
    return rowsDeleted;
}


@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
    int type = URI_MATCHER.match(uri);
    SQLiteDatabase db = dbHelper.getWritableDatabase();
    int rowsUpdated;
    switch (type) {
        case ITEM:
            rowsUpdated = db.update(Constants.ITEM_TABLE, values, selection, selectionArgs);
            break;

        case ITEMS:
            String id = uri.getLastPathSegment();
            if (TextUtils.isEmpty(selection)) {
                rowsUpdated = db.update(Constants.ITEM_TABLE, values, Constants.COLUMN_ID + "=" + id, null);
            } else {
                rowsUpdated = db.update(Constants.ITEM_TABLE, values, Constants.COLUMN_ID + "=" + id + " and " + selection, selectionArgs);
            }
            break;

        default:
            throw new IllegalArgumentException("Unknown URI: " + uri);
    }
    getContext().getContentResolver().notifyChange(uri, null);
    return rowsUpdated;
}
}

DBHelper.java

public class DbHelper extends SQLiteOpenHelper {

private static final String DATABASE_NAME = "MyApp.db";
private static final int DATABASE_VERSION = 1;

//create item table statement
private static final String CREATE_TABLE_ITEM = "create item table "
        + Constants.ITEM_TABLE
        + "("
        + Constants.COLUMN_ID + " integer primary key autoincrement, "
        + Constants.COLUMN_ITEM + " text not null, "
        + Constants.COLUMN_QUANTITY + " integer not null, "
        + Constants.COLUMN_UNIT + " integer not null, "
        + Constants.COLUMN_PRICE + " integer not null, "
        + Constants.COLUMN_STORE + " text not null, "
        + ")";

public DbHelper(Context context) {

    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}


@Override
public void onCreate(SQLiteDatabase db) {

    String CREATE_TABLE_ITEM = "create item table "
            + Constants.ITEM_TABLE
            + "("
            + Constants.COLUMN_ID + " integer primary key autoincrement, "
            + Constants.COLUMN_ITEM + " text not null, "
            + Constants.COLUMN_QUANTITY + " integer not null, "
            + Constants.COLUMN_UNIT + " integer not null, "
            + Constants.COLUMN_PRICE + " integer not null, "
            + Constants.COLUMN_STORE + " text not null, "
            + ")";

    //create the required table
    db.execSQL(CREATE_TABLE_ITEM);

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + Constants.ITEM_TABLE);
    //create new table
    onCreate(db);
}
}

Constants.java

public class Constants {

public static final String ITEM_TABLE = "items";

public static final String COLUMN_ID = "_id";
public static final String COLUMN_ITEM = "item";
public static final String COLUMN_QUANTITY = "quantity";
public static final String COLUMN_UNIT = "unit";
public static final String COLUMN_PRICE = "price";
public static final String COLUMN_STORE = "store";

public static final String[] COLUMNS = {
        Constants.COLUMN_ID,
        Constants.COLUMN_ITEM,
        Constants.COLUMN_QUANTITY,
        Constants.COLUMN_UNIT,
        Constants.COLUMN_PRICE,
        Constants.COLUMN_STORE

};
}

logcat的

java.lang.RuntimeException: Unable to start activity ComponentInfo{*package name removed*.activities.MainActivity}: android.database.sqlite.SQLiteException: no such table: items (code 1): , while compiling: SELECT _id, item, quantity, unit, price, store FROM items
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.database.sqlite.SQLiteException: no such table: items (code 1): , while compiling: SELECT _id, item, quantity, unit, price, store FROM items
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
at android.database.sqlite.SQLiteQueryBuilder.query(SQLiteQueryBuilder.java:400)
at android.database.sqlite.SQLiteQueryBuilder.query(SQLiteQueryBuilder.java:294)
at *package name removed*.data.GPContentProvider.query(GPContentProvider.java:75)
at android.content.ContentProvider.query(ContentProvider.java:857)
at android.content.ContentProvider$Transport.query(ContentProvider.java:200)
at android.content.ContentResolver.query(ContentResolver.java:461)
at android.content.ContentResolver.query(ContentResolver.java:404)
at zarry.gptest.data.ItemManager.getAllItems(ItemManager.java:63)
at *package name removed*.fragments.ItemListFragment.setupList(ItemListFragment.java:96)
at *package name removed*.fragments.ItemListFragment.onCreateView(ItemListFragment.java:50)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1965)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1078)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1259)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1624)
at android.support.v4.app.FragmentController.execPendingActions(FragmentController.java:330)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:547)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
at android.app.Activity.performStart(Activity.java:5241)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2157)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233) 
at android.app.ActivityThread.access$800(ActivityThread.java:135) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 
at dalvik.system.NativeStart.main(Native Method)

提前致谢

Answer 1

您的create table查询错误。

 String CREATE_TABLE_ITEM = "create item table "

create和table

之间的项目

应该是

 String CREATE_TABLE_ITEM = "create table " + Constants.ITEM_TABLE ..

Answer 2

你错过了一个空白：

在此处创建表项（_ id integer

和额外的逗号：

将文字存储为空，＆lt; -this ）

并在结尾添加分号。

 String CREATE_TABLE_ITEM = "create table "
        + Constants.ITEM_TABLE
        + " ("
        + Constants.COLUMN_ID + " integer primary key autoincrement, "
        + Constants.COLUMN_ITEM + " text not null, "
        + Constants.COLUMN_QUANTITY + " integer not null, "
        + Constants.COLUMN_UNIT + " integer not null, "
        + Constants.COLUMN_PRICE + " integer not null, "
        + Constants.COLUMN_STORE + " text not null);";

SQLiteException：没有这样的表？

2 个答案: