Question

当我在Android中的sqliteDB中插入新行时，它将始终在数据库中占用其前一行吗？

模型类：

ModelProducts：

public class ModelProducts {
private String prodId;
private String prodName;
private String prodDesc;
private String prodPrice;


public ModelProducts() {
super();
}

public ModelProducts(String prodId, String prodName, String prodDesc, String prodPrice) {
this.prodId = prodId;
this.prodName = prodName;
this.prodDesc = prodDesc;
this.prodPrice = prodPrice;
}

public ModelProducts(String prodId, String prodName, String prodPrice){

this.prodId = prodId;
this.prodName = prodName;
this.prodPrice = prodPrice;
}

public String getProdId() {
return prodId;
}

public String getProdName() {
return prodName;
}

public String getProdDesc() {
return prodDesc;
}

public String getProdPrice() {
return prodPrice;
}

public void setProdId(String prodId) {
this.prodId = prodId;
}

public void setProdName(String prodName) {
this.prodName = prodName;
}

public void setProdDesc(String prodDesc) {
this.prodDesc = prodDesc;
}

public void setProdPrice(String prodPrice) {
this.prodPrice = prodPrice;
}

}

ModelCartItem：

public class ModelCartItem {

private ModelProducts product;
private int productQuantity;

public ModelCartItem() {
    super();
}

public ModelProducts getProduct() {
    return product;
}

public int getProductQuantity() {
    return productQuantity;
}

public void setProduct(ModelProducts product) {
    this.product = product;
}

public void setProductQuantity(int productQuantity) {
    this.productQuantity = productQuantity;
}

}

在DatabaseHelper类

中

// Database Version
private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "shoppingCart";

 // Table Names
 private static final String TABLE_CART = "cart";


 //CART Table - column names
 private static final String KEY_PRODID = "prod_id";
 private static final String KEY_PROD_NAME = "prod_name";
 private static final String KEY_PROD_PRICE = "prod_price";
 private static final String KEY_PROD_QUANTITY = "prod_quantity";

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

创建表：

// Cart table create statement
    private static final String CREATE_TABLE_CART = "CREATE TABLE " + TABLE_CART
            + "(" + KEY_PRODID + " TEXT PRIMARY KEY," 
            + KEY_PROD_NAME + " TEXT," 
            + KEY_PROD_PRICE + " TEXT," 
            + KEY_PROD_QUANTITY + " TEXT"
            + ")";  
@Override
public void onCreate(SQLiteDatabase db) {

    // creating required tables
    db.execSQL(CREATE_TABLE_CART);
}

插入：

 public void addtoCart(ModelCartItem item, int productQuantity) {

    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_PRODID, item.getProduct().getProdId());
    values.put(KEY_PROD_NAME, item.getProduct().getProdName());
    values.put(KEY_PROD_PRICE, item.getProduct().getProdPrice());
    values.put(KEY_PROD_QUANTITY, item.getProductQuantity());

    // insert row
    db.insert(TABLE_CART, null, values);

    db.close();


}

当我在Activity 1中使用下面的代码添加Item时，即ProductActivity其中datamodel是ModelProducts类的对象，而ModelProducts类中的数据来自onclick of button。

在这个Activity中，我在onCreate（）方法中创建了一个Db helper的对象

DatabaseHelper databaseHelper  = new DatabaseHelper(this);

这是在onCreate（）方法

中在DB中插入新行的代码

 Log.d("TAG", "Product Id: "+ dataModel.getProdId());
                  Log.d(TAG, "Product Name: " + dataModel.getProdName());
                  Log.d(TAG, "Product Description: " + dataModel.getProdDesc());
                  Log.d(TAG, "Product Price: " + dataModel.getProdPrice());
int productQuantity = 1;
                      ModelCartItem item = new ModelCartItem();
                      item.setProduct(dataModel);
                      item.setProductQuantity(productQuantity);

                      databaseHelper.addtoCart(item, productQuantity);

之后我想将所有添加的数据检索到另一个活动，即BasketActivity，所以问题是最后插入的行值是否在行的列表项中。
在onCreate（）方法的Basket Activity中，运行以下代码

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_basket);

    databaseHelper = new DatabaseHelper(this);
    listView = (ListView)findViewById(R.id.listViewProduct);
    imagebtnCategory = (ImageButton)findViewById(R.id.imagebtnCategory);

    ArrayList<ModelCartItem>arrayList3 = databaseHelper.getAllCartItem();

    for(ModelCartItem cartItem: arrayList3){

        Log.d("ID product: ", cartItem.getProduct().getProdId());
        Log.d("Name product: ", cartItem.getProduct().getProdName());
        Log.d("Price product: ", cartItem.getProduct().getProdPrice());
        Log.d("Quantity product: ", ""+cartItem.getProductQuantity());
    }
 }

这是从DB

获取所有项目的方法

public ArrayList<ModelCartItem> getAllCartItem() {
    ModelProducts modelProducts = new ModelProducts();
    ModelCartItem cartItem = new ModelCartItem();
    ArrayList<ModelCartItem> todos = new ArrayList<ModelCartItem>();

    String selectQuery = "SELECT  * FROM " + TABLE_CART;

    Log.e(LOG, selectQuery);

    SQLiteDatabase db = this.getReadableDatabase();
    Cursor c = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (c.moveToFirst()) {
        do {
            modelProducts.setProdId((c.getString((c.getColumnIndex(KEY_PRODID)))));
            modelProducts.setProdName((c.getString((c.getColumnIndex(KEY_PROD_NAME)))));
            modelProducts.setProdPrice((c.getString((c.getColumnIndex(KEY_PROD_PRICE)))));

            cartItem.setProduct(modelProducts);
            cartItem.setProductQuantity(Integer.parseInt(c.getString(c.getColumnIndex(KEY_PROD_QUANTITY))));

            // adding to cartItem list
            todos.add(cartItem);

        } while (c.moveToNext());
    }

    return todos;
}

输入是：
Id 279的值是

Product Name is Mafalde ai calamari,
Product Price is 9.00
Quantity is 1

Id 310的值是

Product Name is Italiano,
Product Price is 5.00
Quantity is 2

然后输出将像LogCat中的那样：

ID Product: 279
Name Product: Mafalde ai calamari
Price Product: 9.00 
Quantity product: 1


ID Product: 279
Name Product: Mafalde ai calamari
Price Product: 9.00 
Quantity product: 1

这里，id 279的值重复两次，但我输入为id 279和310。

最后，我的问题是我想要所有那些存在于Arraylist之上的项目？还有如上所示不重复的项目输出？

我想要那样的输出

ID Product: 279
Name Product: Mafalde ai calamari
Price Product: 9.00 
Quantity product: 1


ID Product: 310
Name Product: Italiano
Price Product: 5.00 
Quantity product: 2

图像：

Answer 1

在getAllCartItem()中，移动

ModelProducts modelProducts = new ModelProducts();
ModelCartItem cartItem = new ModelCartItem();

在do - while循环中，以便为每一行创建新的模型对象，而不是之前重用的那些对象。

当我在Android中的sqliteDB中插入新行时，它将始终在数据库中占用其前一行？

1 个答案: