在android中使用SQLite帮助程序创建数据库

Question

我正在创建一个非常基本的android数据库应用程序，但试图超出我使用SQLiteOpenHelper创建的数据库的活动正在捕获SQLiteException并创建“数据库未找到”的敬酒。下面是我的工作

活动excessing数据库

package com.hfad.starbuzz; 

import android.app.ListActivity; 
import android.content.Intent; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteException; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
import android.widget.SimpleCursorAdapter; 
import android.widget.Toast; 


public class DrinkCategoryActivity extends ListActivity { 
    private Cursor cursor; 
    private SQLiteDatabase db; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     ListView listview = getListView(); 
     try{ 
      SQLiteOpenHelper starbuzzDatabaseHelper = new StarbuzzDatabaseHelper(this); 
      db = starbuzzDatabaseHelper.getReadableDatabase(); 
      cursor = db.query("Drink",new String[]{"_id","NAME"},null,null,null,null,null); 
      SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,android.R.layout.simple_list_item_1, 
        cursor,new String[]{"NAME"},new int[]{android.R.id.text1},0); 
      listview.setAdapter(adapter); 
     } 
     catch(SQLiteException e){ 
      Toast.makeText(this, "Database not found", Toast.LENGTH_SHORT).show(); 
     } 

    } 

    @Override 
    protected void onListItemClick(ListView l, View v, int position, long id) { 
     Intent intent = new Intent(DrinkCategoryActivity.this,DrinkActivity.class); 
     intent.putExtra(DrinkActivity.EXTRADRINKO,(int) id); 
     startActivity(intent); 
    } 

    @Override 
    protected void onDestroy() { 
     super.onDestroy(); 
     cursor.close(); 
     db.close(); 

    } 
} 

数据库助手代码

package com.hfad.starbuzz; 

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

/** 
* Created by user on 11/7/2016. 
*/ 

public class StarbuzzDatabaseHelper extends SQLiteOpenHelper { 
    private static final int DB_VERSION = 1; 
    private static final String DB_NAME = "Starbuzz"; 

    public StarbuzzDatabaseHelper(Context context){ 
     super(context,DB_NAME,null,DB_VERSION); 
    } 
    @Override 
    public void onCreate(SQLiteDatabase db) { 
      updateDatabase(db,0,DB_VERSION); 
    } 
    private void insert(String name , String description , int id , SQLiteDatabase db){ 
     ContentValues drinkValues = new ContentValues(); 
     drinkValues.put("NAME",name); 
     drinkValues.put("DESCRIPTION",description); 
     drinkValues.put("IMAGE_RESOURCE_ID",id); 
     db.insert("DRINK", null , drinkValues); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
       updateDatabase(db,oldVersion,newVersion); 
    } 
    private void updateDatabase(SQLiteDatabase db , int oldVersion , int newVersion){ 
      db.execSQL("create table DRINK(" + 
        "_id primary key INTEGER AUTOINCREMENT," 
        + "NAME TEXT," 
        +"DESCRIPTION TEXT," 
        +"IMAGE_RESOURCE_ID INTEGER);"); 
      insert("latte","Espresso and steamed milk",R.drawable.latte,db); 
      insert("cappuccino","Espresso and steamed milk and lollypop for u to suck, SUCKER",R.drawable.cappuccino,db); 
      insert("filter","to filter your ass off because it is fucking dirty",R.drawable.filter,db); 

    } 
} 

Answer 1

试试这个

private static DatabaseHelper ourInstance; 

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

public static DatabaseHelper getInstance(Context context) { 
    if (ourInstance == null) 
     ourInstance = new DatabaseHelper(context); 
    ourInstance.getReadableDatabase(); 
    return ourInstance; 
} 

@Override 
public void onCreate(SQLiteDatabase db) { 

    String CREATE_TABLE_TODO = " CREATE TABLE " + TABLE_NAME + "(" + TASK_ID + 
      " INTEGER PRIMARY KEY," + TASK_NAME + " TEXT, " + TASK_TIME + " TEXT, " + TASK_DATE + " TEXT " + ") "; 
    db.execSQL(CREATE_TABLE_TODO); 
}