Question

我正在尝试将数据插入到SQLite数据库中，但是应用程序因为某些原因而崩溃，我对此一无所知。我刚刚学会了“如何创建数据库和表，如何插入数据（但似乎没有）”请不要问我Android Studio对崩溃的说法是什么我无法在笔记本电脑上运行app “Android模拟器或其他任何东西”的帮助。

以下是我的DatabaseHelper代码，扩展SQLiteOpenHelper

package com.famiddle.genius.businessmanager;

import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHelper extends SQLiteOpenHelper {

// DECLARING NAME FOR THE DATABASE AND THE TABLE
public static final String DATABASE_NAME = "imported_items";
public static final String TABLE_NAME = "stock";

// DECLARING NAME FOR THE COLUMNS
public static final String COL_1 = "ID";
public static final String COL_2 = "ITEMS_NAME";
public static final String COL_3 = "QUANTITY";
public static final String COL_4 = "COST";
public static final String COL_5 = "TOTAL_COST";

// DEFAULT CONSTRUCTOR
public DatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, 1);
}

// IT CREATES TABLE
@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL("CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, ITEMS_NAME TEXT, QUANTITY INTEGER, COST INTEGER, TOTAL_COST INTEGER");
}

// IT DROPS TABLE, IF IT ALREADY EXISTS
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
    onCreate(db); //I DON'T KNOW WHY IT IS HERE, PLEASE TELL ME MORE ABOUT 
//   IT IN COMMENTS
}

// IT INSERTS DATA OR VALUES IN TABLE
public boolean insertData(String itemsName, int quantity, int cost, int totalCost) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(COL_2, itemsName);
    contentValues.put(COL_3, quantity);
    contentValues.put(COL_4, cost);
    contentValues.put(COL_5, totalCost);
    long result = db.insert(TABLE_NAME, null, contentValues);
    //db.close();
    if (result == -1){
        return false;
    }else {return true;}
   // return result != -1;
}
}

这是库存片段的代码，其中正在调用数据库实例和使用

public class Stock extends Fragment {
DatabaseHelper dataBase;
ArrayList<String> items;

SharedPreferences prefs;
SharedPreferences.Editor editor;

 public Stock() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.stock, container, false);

    prefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
    editor = prefs.edit();
    if(prefs.getBoolean("has_not_created?", true)) {
        // INITIALIZING ARRAY LIST THAT CONTAINS ITEMS NAME
        items = new ArrayList<>();
        items.add("One");
        items.add("Two");
        items.add("Three");
        items.add("Four");
        items.add("Five");
        items.add("Six");

        // INITIALIZING DATABASE
        dataBase = new DatabaseHelper(getContext());
        // CREATING A LOOP FOR INSERTING ITEMS NAMES ONE BY ONE
        for (int i = 0; i < items.size(); i++) {
             Boolean isInserted = dataBase.insertData(items.get(i), 0, 0, 0);
            Toast.makeText(getActivity(), items.get(i) + " has been inserted into database" + isInserted , Toast.LENGTH_SHORT).show();
        }
        // PUTTING 'FALSE' IN SHARED PREFERENCE OBJECT
        // THEN IT WILL NOT ALLOW THE CODE TO RUN
        editor.putBoolean("has_not_created?", false);
        editor.apply();
    }

有人可以告诉我我的代码有什么问题吗？我是从Android教程中学到的。

Answer 1

您的错误发生在onCreate()。

您要打开括号，但不要在任何地方关闭它。所以它应该是::

 db.execSQL("CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, ITEMS_NAME TEXT, QUANTITY INTEGER, COST INTEGER, TOTAL_COST INTEGER)");

将数据插入sqlite数据库时出现了一些错误！应用程序一直在崩溃

1 个答案: