我的 sqlite 数据库只插入一项 android studio (java)
Posted
技术标签:
【中文标题】我的 sqlite 数据库只插入一项 android studio (java)【英文标题】：My sqlite database is only inserting one item android studio (java) 【发布时间】：2021-09-27 16:09:09 【问题描述】：我不知道怎么做，但我的 sqlite 数据库似乎只能存储一项而不是很多。每当我添加一个项目时，我的数据库助手似乎都会返回 false。我该如何解决？
每次我将产品实例添加到数据库时，它都会返回 false 并且只保留一个项目，但不再添加任何项目。
这是我的产品类别：
public class ProductModel
private int id;
private String name;
private float price;
private int quantity;
private float total;
private int inBasket;
public ProductModel(int id, String name, float price, int quantity, int inBasket)
this.id = id;
this.name = name;
this.price = price;
this.quantity = quantity;
this.total = this.price * this.quantity;
this.inBasket = inBasket;
public ProductModel()
@Override
public String toString()
String n = this.name.toUpperCase();
return n + "\n Price:" + price + "\n Qty:" + quantity + "\n inBasket:"+inBasket+"\n Total:" + total;
public int getId()
return id;
public void setId(int id)
this.id = id;
public String getName()
return name;
public void setName(String name)
this.name = name;
public float getPrice()
return price;
public void setPrice(float price)
this.price = price;
public int getQuantity()
return quantity;
public void setQuantity(int quantity)
this.quantity = quantity;
public float getTotal()
return total;
public void setTotal(float price, int quantity)
this.total = price * quantity;
public int getInBasket()
return inBasket;
public void setInBasket(int inBasket)
this.inBasket = inBasket;
这是我的数据库助手：
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import androidx.annotation.Nullable;
import java.util.ArrayList;
import java.util.List;
public class DataBaseHelper extends SQLiteOpenHelper
public static final String PRODUCT_TABLE = "PRODUCT_TABLE";
public static final String COL_ID = "PRODUCT_ID";
public static final String COL_NAME = "PRODUCT_NAME";
public static final String COL_PRICE = "PRODUCT_PRICE";
public static final String COL_QUANTITY = "PRODUCT_QUANTITY";
public static final String COL_TOTAL = "PRODUCT_TOTAL";
public static final String COL_IN_BASKET = "PRESENT_BASKET";
public static final String CREATE_TABLE_QUERY = "CREATE TABLE "+ PRODUCT_TABLE +"(" +
COL_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
COL_NAME + " TEXT, " +
COL_PRICE + " FLOAT, " +
COL_QUANTITY + " INT, " +
COL_TOTAL + " FLOAT, " +
COL_IN_BASKET + " INT);";
public DataBaseHelper(@Nullable Context context)
super(context, "ProductList.db", null, 1);
@Override
public void onCreate(SQLiteDatabase db)
db.execSQL(CREATE_TABLE_QUERY);
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
public boolean addItem(ProductModel productModel)
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
cv.put(COL_ID, productModel.getId());
cv.put(COL_NAME, productModel.getName());
cv.put(COL_PRICE, productModel.getPrice());
cv.put(COL_QUANTITY, productModel.getQuantity());
cv.put(COL_TOTAL, productModel.getTotal());
cv.put(COL_IN_BASKET, productModel.getInBasket());
long insert = db.insert(PRODUCT_TABLE, null, cv);
if(insert==-1)
return false;
else return true;
public boolean deleteOne(ProductModel productModel)
SQLiteDatabase db = this.getReadableDatabase();
String QueryString = "DELETE FROM "+PRODUCT_TABLE+" WHERE " +COL_ID+ "=" +productModel.getId();
Cursor cursor = db.rawQuery(QueryString, null);
if(cursor.moveToFirst())
return true;
else return false;
public List<ProductModel> getEverything()
List<ProductModel> returnList = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
String QueryString = "SELECT * FROM " + PRODUCT_TABLE;
Cursor cursor = db.rawQuery(QueryString, null);
if(cursor.moveToFirst())
do
int productID = cursor.getInt(0);
String productName = cursor.getString(1);
float productPrice = cursor.getFloat(2);
int productQuantity = cursor.getInt(3);
int inBasket = cursor.getInt(5);
ProductModel newProduct = new ProductModel(productID, productName, productPrice, productQuantity, inBasket);
returnList.add(newProduct);
while(cursor.moveToNext());
else /*nothing*/
//close both cursor & db when done
cursor.close();
db.close();
return returnList;
以及处理向数据库添加数据的相应活动：
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
public class MainActivity extends AppCompatActivity
Button bt_add;
EditText et_name, et_price, et_qty;
ListView lv_itemlist;
ArrayAdapter productArrayAdapter;
DataBaseHelper dataBaseHelper;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bt_add = findViewById(R.id.bt_add);
et_name = findViewById(R.id.et_name);
et_price = findViewById(R.id.et_price);
et_qty = findViewById(R.id.et_qty);
lv_itemlist = findViewById(R.id.lv_itemlist);
dataBaseHelper = new DataBaseHelper(MainActivity.this);
ShowProductOnListView(dataBaseHelper);
bt_add.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
ProductModel productModel = new ProductModel();
try
productModel.setId(-1);
productModel.setName(et_name.getText().toString());
productModel.setPrice(Float.parseFloat(et_price.getText().toString()));
productModel.setQuantity(Integer.parseInt(et_qty.getText().toString()));
productModel.setInBasket(1);//1 for true, 0 for false;
productModel.setTotal(productModel.getPrice(), productModel.getQuantity());
Log.d("CheckAdd" ,""+productModel.getTotal()); //checks if the total is in the product
catch (Exception e)
Log.d("CheckAdd" ,"Error on btn_add");
DataBaseHelper databaseHelper = new DataBaseHelper(MainActivity.this);
boolean success = databaseHelper.addItem(productModel);
Log.d("CheckAdd" ,"Success value:"+success);//expected true
ShowProductOnListView(dataBaseHelper);
);
lv_itemlist.setOnItemClickListener(new AdapterView.OnItemClickListener()
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
ProductModel clickedProduct = (ProductModel) parent.getItemAtPosition(position);
dataBaseHelper.deleteOne(clickedProduct);
ShowProductOnListView(dataBaseHelper);
);
private void ShowProductOnListView(DataBaseHelper dataBaseHelper)
productArrayAdapter = new ArrayAdapter<ProductModel>(MainActivity.this, android.R.layout.simple_list_item_1,dataBaseHelper.getEverything());
lv_itemlist.setAdapter(productArrayAdapter);
【问题讨论】：
你会添加你的数据库架构吗？因为我的猜测是，您的 ID 字段必须是唯一的，并且您总是尝试添加具有相同 id (-1) 的新产品。 您需要更改productModel.setId(-1) ，因为它添加了具有相同 id 的产品。即-1
@TheTanic 我认为我没有架构。我刚刚在 databasehelper 中声明了列字符串。我会尝试对 (-1) id 做一些事情
@Priyaank 我更正了它是 id()。谢谢
因为您在函数“addItem”中传递了一个项目，所以只添加了一个项目。使用循环或项目列表管理它。
【参考方案1】：
使用这个简单的设置数据到数据库或从数据库获取数据
private ContentValues modelToContentValue(Model model)
ContentValues contentValues = new ContentValues();
contentValues.put("Price" , model.getPrice());
// And else ....
return contentValues;
private ArrayList<Model> cursorToModel(Cursor cursor)
ArrayList<Model> Models = new ArrayList<>();
cursor.moveToFirst();
while (!cursor.isAfterLast())
Model model = new Model();
model.setPrice(cursor.getFloat(cursor.getColumnIndex("Price")));
// And else ....
models.add(model);
cursor.moveToNext();
return models;
我用这个方法插入到表格中
public boolean insertGroup(ArrayList<Model> models)
SQLiteDatabase db = dbHelper.getWritableDatabase();
try
db.beginTransaction();
for (Model model : models)
ContentValues contentValues = modelToContentValue(model);
db.insertOrThrow("TableName" , null , contentValues);
db.setTransactionSuccessful();
db.endTransaction();
db.close();
return true;
catch (Exception exception)
exception.printStackTrace();
if (db.inTransaction())
db.endTransaction();
if (db.isOpen())
db.close();
return false;
我用这个方法读表
public ArrayList<Model> getAll()
ArrayList<Model> models = new ArrayList<>();
try
SQLiteDatabase db = dbHelper.getReadableDatabase();
Cursor cursor = db.query("TableName", allColumns(), null, null, null, null, null);
if (cursor != null)
if (cursor.getCount() > 0)
models = cursorToModel(cursor);
cursor.close();
db.close();
catch (Exception exception)
exception.printStackTrace();
private String[] allColumns()
return new String[]
"Price",
// and else ....
;
【讨论】：
【参考方案2】：在bt_add的监听器内部，有这行：
productModel.setId(-1);
您将productModel 的ID 设置为-1。
然后，第一次执行代码时，插入的新行PRODUCT_ID 等于-1。
但是，对于任何随后对addItem() 的调用，插入都会失败，因为PRODUCT_ID 是表的PRIMARY KEY，这意味着它是唯一的，并且PRODUCT_ID 等于@987654331 的行不能超过1 行@.
列PRODUCT_ID，因为您将其定义为INTEGER PRIMARY KEY AUTOINCREMENT，所以插入代码中不需要任何值。这将由 SQLite 处理。
所以，从监听器中删除这一行：
productModel.setId(-1);
还有这一行：
cv.put(COL_ID, productModel.getId());
来自addItem()。
【讨论】：
以上是关于我的 sqlite 数据库只插入一项 android studio (java)的主要内容，如果未能解决你的问题，请参考以下文章
Sqlite 内容提供程序：插入行，但应用程序崩溃无法插入行