按一个按钮将项添加到sql数据库

时间:2017-03-01 12:46:34

标签: java android sql sqlite

我试图将某些内容添加到列表中,同时将其添加到数据库中。这可以通过按下按钮来完成。当我将项目添加到列表时,这工作正常,但是当我添加数据库功能时,它停止工作。错误始于:

db.execSQL(CREATETABLE);

public class ItemDAO extends SQLiteOpenHelper {

        private static final String DATABASENAME = "ItemsDB";
        private static final Integer DATABASEVERSION = 1;

        private static final String TABLEITEM = "Table";
        private static final String ITEM = "name";
        private static final String ID = "id";

        private Context context;

        public ItemDAO(Context context) {
            super(context, DATABASENAME, null, DATABASEVERSION);
            this.context = context;
        }

        @Override
        public void onCreate(SQLiteDatabase db) {

            String createTable = "CREATE TABLE " + TABLEITEM + "("
                    + ID + " INTEGER PRIMARY KEY, "
                    + ITEM + " TEXT" + " )";

            db.execSQL(createTable);
        }

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

        public void addItemToDatabase(Item item){

            ContentValues fila = new ContentValues();

            fila.put(ID, item.getId());
            fila.put(ITEM, item.getName());

            SQLiteDatabase database = getWritableDatabase();

            database.insert(TABLEITEM, null, fila);

            database.close();
        }

        public List<Item> getItemsFromDatabases(){

            String selectQuery = "SELECT * FROM " + TABLEITEM;

            SQLiteDatabase database = getReadableDatabase();

            Cursor cursor = database.rawQuery(selectQuery, null);
            List<Item> itemList = new ArrayList<>();

            while(cursor.moveToNext()){

                Item item = getItem(cursor);
                itemList.add(item);
            }

            cursor.close();
            database.close();
            return itemList;
        }


        private Item getItem(Cursor cursor){
            Item item = new Item();

            Integer itemID = cursor.getInt(cursor.getColumnIndex(ID));
            item.setId(itemID);

            String itemName = cursor.getString(cursor.getColumnIndex(ITEM));
            item.setName(itemName);
            return item;
        }
    }

//另一个班级

public class ItemController {

    public void addItemToDB(Item item, Context context){
        ItemDAO itemDAO = new ItemDAO(context);
        itemDAO.addItemToDatabase(item);
    }

    public List<Item> getItemsFromDB(Context context){
        ItemDAO itemDAO = new ItemDAO(context);
        return itemDAO.getItemsFromDatabases();
    }

}

//另一个班级

public class FragmentMyList extends Fragment {
    private EditText editTxt;
    private Button btn;
    private ListView list;
    private ArrayAdapter<String> adapter;
    private ArrayList<String> arrayList;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View vistaADevolver = inflater.inflate(R.layout.fragment_my_list, container, false);

        editTxt = (EditText)vistaADevolver.findViewById(R.id.editText);
        btn = (Button) vistaADevolver.findViewById(R.id.button);
        list = (ListView) vistaADevolver.findViewById(R.id.recyclerView);
        arrayList = new ArrayList<>();

        // Adapter: You need three parameters 'the context, id of the layout (it will be where the data is shown),
        // and the array that contains the data
        adapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_spinner_item, arrayList);

        // Here, you set the data in your ListView
        list.setAdapter(adapter);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ItemController itemController = new ItemController();

                String itemName = editTxt.getText().toString();
                Item item = new Item();
                item.setName(itemName);
                item.setId(0);
                itemController.addItemToDB(item, getActivity());

                // this line adds the data of your EditText and puts in your array
                arrayList.add(itemName);
                // next thing you have to do is check if your adapter has changed
                adapter.notifyDataSetChanged();
            }
        });
        return vistaADevolver;
    }
}

E / AndroidRuntime:致命异常:主要                   处理:com.segunfamisa.sample.bottomnav,PID:2792                   android.database.sqlite.SQLiteException:near&#34; Table&#34 ;:语法错误(代码1):,同时编译:CREATE TABLE Table(id INTEGER PRIMARY KEY,name TEXT)                       在android.database.sqlite.SQLiteConnection.nativePrepareStatement(本机方法)                       在android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)                       在android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)                       在android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)                       在android.database.sqlite.SQLiteProgram。(SQLiteProgram.java:58)                       在android.database.sqlite.SQLiteStatement。(SQLiteStatement.java:31)                       在android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1677)                       在android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1608)                       在com.segunfamisa.sample.bottomnav.ItemDAO.onCreate(ItemDAO.java:45)                       在android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:251)                       在android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)                       在com.segunfamisa.sample.bottomnav.ItemDAO.addItemToDatabase(ItemDAO.java:63)                       在com.segunfamisa.sample.bottomnav.ItemController.addItemToDB(ItemController.java:15)                       在com.segunfamisa.sample.bottomnav.FragmentMyList $ 1.onClick(FragmentMyList.java:52)                       在android.view.View.performClick(View.java:5637)                       在android.view.View $ PerformClick.run(View.java:22429)                       在android.os.Handler.handleCallback(Handler.java:751)                       在android.os.Handler.dispatchMessage(Handler.java:95)                       在android.os.Looper.loop(Looper.java:154)                       在android.app.ActivityThread.main(ActivityThread.java:6119)                       at java.lang.reflect.Method.invoke(Native Method)                       在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:886)                       在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

3 个答案:

答案 0 :(得分:1)

Table是SQLLite中的保留关键字,不能将其用作表名。 http://www.sqlite.org/lang_keywords.html

还要注意列名TEXT。这不是在SQLLite中保留的,而是在MySQL中,例如它。使用此列名可防止您以后切换到其他数据库供应商。

答案 1 :(得分:1)

为表格尝试其他名称,因为它是关键字,并在此处使用表格名称\&#39;或\&#34;表名在这里\&#34;

答案 2 :(得分:0)

我猜你必须将的表名放入某种逃避字符中(google说它的“ - 双引号”)

ItemDAO中的

 private static final String TABLEITEM = "\"Table\"";

表是SQLLite中的保留关键字,因此通常错误(练习)想法将保留关键字用作表和列名称。但是,如果必须,您必须逃避这些名称:reference