Question

我正在创建一个非常基本的android数据库应用程序，但尝试超出我使用SQLiteOpenHelper创建的数据库的活动正在捕获SQLiteException并创建一个“找不到数据库”的toast。以下是我的工作

超出数据库的活动

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();

    }
}

数据库帮助程序代码

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);
}

使用SQLite帮助器在android中创建数据库

1 个答案: