Android的SQLite的：尝试重新打开已关闭的对象对象、Android、SQLite

由网友(渡)分享简介：我试图根据国际标准书号从我的库存表中获取一定的图书数据。不过，我得到一个错误：尝试重新打开已关闭的对象。当我点击一个ListView对象，去一个不同的屏幕，返回到该页面通过完成（），然后尝试点击另一个ListView控件对象只出现此错误。我搬到了字符串searchEntries [] = InventoryAdapte...

我试图根据国际标准书号从我的库存表中获取一定的图书数据。不过，我得到一个错误：尝试重新打开已关闭的对象。当我点击一个ListView对象，去一个不同的屏幕，返回到该页面通过完成（），然后尝试点击另一个ListView控件对象只出现此错误。我搬到了字符串searchEntries [] = InventoryAdapter.getInventoryEntriesByISBN（SEARCHQUERY，ISBN [位置]）; 从 onClickListener 来在previous的为前 onClickListener 循环的，现在它的作品。

为什么，如果我尝试通过getInventoryEntriesByISBN完成（），从另一个活动返回到本次活动后，它不工作？

在SearchResultsScreen发生错误：

 字符串searchEntries [] = InventoryAdapter.getInventoryEntriesByISBN（SEARCHQUERY，ISBN [位置]）;

和推而广之，发生在InventoryAdapter：

 光标光标= db.rawQuery（查询，新的String [] {ISBN}）;

SearchResultsScreen.java

  //设置搜索阵列    的for（int i = 0; I＆LT; isbn.length;我++）    {        searchArray.add（新InventoryItem（ISBN [I]，InventoryAdapter.getTitleAndAuthorByISBN（ISBN由[i]）））;    }    Toast.makeText（getApplicationContext（），searchArray.size（）=+ searchArray.size（），Toast.LENGTH_LONG）.show（）;    //添加自定义适配器数据    适配器=新CustomAdapter（这一点，R.layout.list，searchArray）;    DataList控件的ListView =（ListView控件）findViewById（R.id.list）;    dataList.setAdapter（适配器）;    //在点击============================================== ==========    dataList.setOnItemClickListener（新OnItemClickListener（）{        @覆盖        公共无效onItemClick（适配器视图＆LT;＆GT;母公司，观景，INT位置，                长ID）{            字符串searchEntries [] = InventoryAdapter.getInventoryEntriesByISBN（SEARCHQUERY，ISBN [位置]）;

InventoryAdapter.java（最相关的部分）

 公共字符串[] getInventoryEntriesByISBN（字符串搜索，字符串ISBN）{    的String [] = searchEntry新的String [9];    //查询    查询字符串=从清单中选择*其中ISBN =？;    光标光标= db.rawQuery（查询，新的String [] {ISBN}）;    如果（cursor.getCount（）。1）//标题不存在    {        cursor.close（）;        的for（int i = 0; I＆LT; 9;我++）            searchEntry [I] =未找到;        返回searchEntry;    }    cursor.moveToFirst（）;    //将数据放入相应的变量    INT发布= cursor.getInt（cursor.getColumnIndex（PUBLISH_DATE））;    字符串publishdate =（（整数）发布）的ToString（）;    字符串title = cursor.getString（cursor.getColumnIndex（TITLE））;    笔者字符串= cursor.getString（cursor.getColumnIndex（作者））;    串callNumber = cursor.getString（cursor.getColumnIndex（CALL_NUMBER））;    INT可用= cursor.getInt（cursor.getColumnIndex（AVAILABLE_COUNT））;    字符串availablecount =（（整数）可用）的ToString（）;    INT库存= cursor.getInt（cursor.getColumnIndex（INVENTORY_COUNT））;    字符串inventorycount =（（整数）存货）的ToString（）;    INT由于= cursor.getInt（cursor.getColumnIndex（DUE_PERIOD））;    字符串dueperiod =（（整数）因）的ToString（）;    INT checkoutcount = cursor.getInt（cursor.getColumnIndex（COUNT））;    字符串数=（（整数）checkoutcount）的ToString（）;    //合并变量放入一个阵列    searchEntry [0] = ISBN;    searchEntry [1] =称号;    searchEntry [2] =作者;    searchEntry [3] = publishdate;    searchEntry [4] = callNumber;    searchEntry [5] = availablecount;    searchEntry [6] = inventorycount;    searchEntry [7] = dueperiod;    searchEntry [8] =计数;    cursor.close（）;    返回searchEntry;}公共字符串getTitleAndAuthorByISBN（字符串ISBN）    {        INT entriesFound = getNumSearchEntries（ISBN）;        如果（entriesFound == 0）            entriesFound = 1;        串searchEntry;        //查询        查询字符串=从清单中选择*其中ISBN =？;        光标光标= db.rawQuery（查询，新的String [] {ISBN}）;        如果（cursor.getCount（）。1）//标题不存在        {            cursor.close（）;            searchEntry =未找到;            返回searchEntry;        }        cursor.moveToFirst（）;        //将数据放入相应的变量        字符串title = cursor.getString（cursor.getColumnIndex（TITLE））;        笔者字符串= cursor.getString（cursor.getColumnIndex（作者））;        //变量结合成一个字符串        searchEntry =标题+/+作者;        //关闭游标及返回        cursor.close（）;        返回searchEntry;    }

DataBaseHelper.java

 公共类DataBaseHelper扩展SQLiteOpenHelper{//数据库版本    私有静态最终诠释DATABASE_VERSION = 1;//数据库名称私有静态最后弦乐DATABASE_NAME =database.db;// ============================结束变量================== =========公共DataBaseHelper（上下文的背景下，字符串名称，CursorFactory工厂，INT版）{           超（背景下，名称，厂家，版本）;}公共DataBaseHelper（上下文的背景下）{    超（背景下，DATABASE_NAME，空，DATABASE_VERSION）;}//当盘和辅助类的需求不存在的数据库调用//创建一个新的。@覆盖公共无效的onCreate（SQLiteDatabase _db）{        _db.execSQL（LoginDataBaseAdapter.USER_TABLE_CREATE）;        _db.execSQL（CheckOutDataBaseAdapter.CHECKOUT_TABLE_CREATE）;        _db.execSQL（InventoryAdapter.INVENTORY_TABLE_CREATE）;        _db.execSQL（StatisticsAdapter.STATISTICS_TABLE_CREATE）;}//当有一个数据库版本不匹配意味着该版本，称为//在磁盘上的数据库需要升级到最新版本。@覆盖公共无效onUpgrade（SQLiteDatabase _db，诠释_oldVersion，诠释_newVersion）{        //日志的版本升级。        Log.w（TaskDBAdapter，从版本升级+ _oldVersion +到+ _newVersion +，这将摧毁所有旧数据）;        //升级现有的数据库，以符合新的版本。多        // previous版本可以通过比较_oldVersion和_newVersion处理        //值。        //在升级旧的掉落表        _db.execSQL（DROP TABLE IF EXISTS+ LoginDataBaseAdapter.USER_TABLE_CREATE）;        _db.execSQL（DROP TABLE IF EXISTS+ CheckOutDataBaseAdapter.CHECKOUT_TABLE_CREATE）;        _db.execSQL（DROP TABLE IF EXISTS+ InventoryAdapter.INVENTORY_TABLE_CREATE）;        _db.execSQL（DROP TABLE IF EXISTS+ StatisticsAdapter.STATISTICS_TABLE_CREATE）;        //创建一个新的。        的onCreate（_db）;}}

解决方案

当我点击一个项目，去一个不同的屏幕，通过回到此页完成（），然后尝试单击只出现错误在另一个的ListView对象。

我感动字符串searchEntries [] = InventoryAdapter.getInventoryEntriesByISBN（SEARCHQUERY，ISBN [位置]）;从onClickListener到previous为onClickListener前环和现在的作品。

正确SearchResultsScreen是如下：

SearchResultsScreen.java

  //设置搜索阵列    最终字符串项[] [] =新的String [isbn.length] [9];    的for（int i = 0; I＆LT; isbn.length;我++）    {        searchArray.add（新InventoryItem（ISBN [I]，InventoryAdapter.getTitleAndAuthorByISBN（ISBN由[i]）））;        参赛作品由[i] = InventoryAdapter.getInventoryEntriesByISBN（SEARCHQUERY，ISBN [I]）;    }    Toast.makeText（getApplicationContext（），searchArray.size（）=+ searchArray.size（），Toast.LENGTH_LONG）.show（）;    //添加自定义适配器数据    适配器=新CustomAdapter（这一点，R.layout.list，searchArray）;    DataList控件的ListView =（ListView控件）findViewById（R.id.list）;    dataList.setAdapter（适配器）;    //在点击============================================== ==========    dataList.setOnItemClickListener（新OnItemClickListener（）{        @覆盖        公共无效onItemClick（适配器视图＆LT;＆GT;母公司，观景，INT位置，                长ID）{            字符串searchEntries [] =条目[位置]

I'm trying to get certain book data from my Inventory table based on the ISBN. However, I'm getting an error: "attempt to re-open an already-closed object". The error only occurs when I click a listView object, go to a different screen, go back to this page via "finish()", and then try to click on another listView object. I moved the String searchEntries[] = InventoryAdapter.getInventoryEntriesByISBN(searchQuery, isbn[position]); from the onClickListener to the previous for loop before the onClickListener and now it works.

Why does it not work if I try to getInventoryEntriesByISBN after returning to this activity from another activity via "finish()"?

The error occurs at SearchResultsScreen:

String searchEntries[] = InventoryAdapter.getInventoryEntriesByISBN(searchQuery, isbn[position]);

and by extension, occurs at InventoryAdapter:

Cursor cursor = db.rawQuery(query, new String[] {ISBN});

SearchResultsScreen.java

// Set up search array
    for(int i = 0; i < isbn.length; i++)
    {
        searchArray.add(new InventoryItem(isbn[i], InventoryAdapter.getTitleAndAuthorByISBN(isbn[i])));
    }
    Toast.makeText(getApplicationContext(), "searchArray.size()="+searchArray.size(), Toast.LENGTH_LONG).show();

    // add data in custom adapter
    adapter = new CustomAdapter(this, R.layout.list, searchArray);
    ListView dataList = (ListView) findViewById(R.id.list);
    dataList.setAdapter(adapter);

    // On Click ========================================================
    dataList.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
            String searchEntries[] = InventoryAdapter.getInventoryEntriesByISBN(searchQuery, isbn[position]);

InventoryAdapter.java (Most relevant parts)

public String[] getInventoryEntriesByISBN(String search, String ISBN)
{
    String[] searchEntry = new String [9];
    //Query
    String query = "select * from INVENTORY where ISBN = ?";
    Cursor cursor = db.rawQuery(query, new String[] {ISBN});
    if(cursor.getCount()<1) // title Not Exist
    {
        cursor.close();
        for(int i = 0; i < 9; i++)
            searchEntry[i] = "Not Found";
        return searchEntry;
    }
    cursor.moveToFirst();

    //put data into respective variable
    int publish = cursor.getInt(cursor.getColumnIndex("PUBLISH_DATE"));
    String publishdate = ((Integer)publish).toString();
    String title = cursor.getString(cursor.getColumnIndex("TITLE"));
    String author = cursor.getString(cursor.getColumnIndex("AUTHOR"));
    String callNumber = cursor.getString(cursor.getColumnIndex("CALL_NUMBER"));
    int available = cursor.getInt(cursor.getColumnIndex("AVAILABLE_COUNT"));
    String availablecount = ((Integer)available).toString();
    int inventory = cursor.getInt(cursor.getColumnIndex("INVENTORY_COUNT"));
    String inventorycount = ((Integer)inventory).toString();
    int due = cursor.getInt(cursor.getColumnIndex("DUE_PERIOD"));
    String dueperiod = ((Integer)due).toString();
    int checkoutcount = cursor.getInt(cursor.getColumnIndex("COUNT"));
    String count = ((Integer)checkoutcount).toString();
    //combine variables into one array
    searchEntry[0] = ISBN;
    searchEntry[1] = title;
    searchEntry[2] = author;
    searchEntry[3] = publishdate;
    searchEntry[4] = callNumber;
    searchEntry[5] = availablecount;
    searchEntry[6] = inventorycount;
    searchEntry[7] = dueperiod;
    searchEntry[8] = count;

    cursor.close();
    return searchEntry;
}

public String getTitleAndAuthorByISBN(String ISBN)
    {
        int entriesFound = getNumSearchEntries(ISBN);
        if(entriesFound==0)
            entriesFound = 1;
        String searchEntry;
        //Query
        String query = "select * from INVENTORY where ISBN = ?";
        Cursor cursor = db.rawQuery(query, new String[] {ISBN});
        if(cursor.getCount()<1) // title Not Exist
        {
            cursor.close();
            searchEntry = "Not Found";
            return searchEntry;
        }
        cursor.moveToFirst();
        //put data into respective variable
        String title = cursor.getString(cursor.getColumnIndex("TITLE"));
        String author = cursor.getString(cursor.getColumnIndex("AUTHOR"));
        //combine variables into one String
        searchEntry = title + " / " + author;
        //close cursor and return
        cursor.close();
        return searchEntry;
    }

DataBaseHelper.java

public class DataBaseHelper extends SQLiteOpenHelper
{   
// Database Version
    private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "database.db";

// ============================ End Variables ===========================

public DataBaseHelper(Context context, String name, CursorFactory factory, int version) 
{
           super(context, name, factory, version);
}

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

// Called when no database exists in disk and the helper class needs
// to create a new one.
@Override
public void onCreate(SQLiteDatabase _db) 
{
        _db.execSQL(LoginDataBaseAdapter.USER_TABLE_CREATE);
        _db.execSQL(CheckOutDataBaseAdapter.CHECKOUT_TABLE_CREATE);
        _db.execSQL(InventoryAdapter.INVENTORY_TABLE_CREATE);
        _db.execSQL(StatisticsAdapter.STATISTICS_TABLE_CREATE);
}
// Called when there is a database version mismatch meaning that the version
// of the database on disk needs to be upgraded to the current version.
@Override
public void onUpgrade(SQLiteDatabase _db, int _oldVersion, int _newVersion) 
{
        // Log the version upgrade.
        Log.w("TaskDBAdapter", "Upgrading from version " +_oldVersion + " to " +_newVersion + ", which will destroy all old data");


        // Upgrade the existing database to conform to the new version. Multiple
        // previous versions can be handled by comparing _oldVersion and _newVersion
        // values.
        // on upgrade drop older tables
        _db.execSQL("DROP TABLE IF EXISTS " + LoginDataBaseAdapter.USER_TABLE_CREATE);
        _db.execSQL("DROP TABLE IF EXISTS " + CheckOutDataBaseAdapter.CHECKOUT_TABLE_CREATE);
        _db.execSQL("DROP TABLE IF EXISTS " + InventoryAdapter.INVENTORY_TABLE_CREATE);
        _db.execSQL("DROP TABLE IF EXISTS " + StatisticsAdapter.STATISTICS_TABLE_CREATE);

        // Create a new one.
        onCreate(_db);
}

}

解决方案

The error only occurs when I click an item, go to a different screen, go back to this page via "finish()", and then try to click on another listView object.

I moved the String searchEntries[] = InventoryAdapter.getInventoryEntriesByISBN(searchQuery, isbn[position]); from the onClickListener to the previous for loop before the onClickListener and now it works.

The correct SearchResultsScreen is below:

SearchResultsScreen.java

// Set up search array
    final String Entries[][] = new String[isbn.length][9];
    for(int i = 0; i < isbn.length; i++)
    {
        searchArray.add(new InventoryItem(isbn[i], InventoryAdapter.getTitleAndAuthorByISBN(isbn[i])));
        Entries[i] = InventoryAdapter.getInventoryEntriesByISBN(searchQuery, isbn[i]);
    }
    Toast.makeText(getApplicationContext(), "searchArray.size()="+searchArray.size(), Toast.LENGTH_LONG).show();

    // add data in custom adapter
    adapter = new CustomAdapter(this, R.layout.list, searchArray);
    ListView dataList = (ListView) findViewById(R.id.list);
    dataList.setAdapter(adapter);

    // On Click ========================================================
    dataList.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
            String searchEntries[] = Entries[position];

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相关专题：对象；Android ；SQLite ；发布时间：2023-09-08 09:51:42