安卓IllegalStateException异常，数据库已经关闭 [英] android IllegalStateException, database already closed

问题描述

我使用SimpleCursorAdapter和数据库表来填充列表。该列表被填充，我可以点击列表中的项目，打开所需的项目（这将启动一个新的活动）。问题是，当我preSS返回键，我得到了下面的错误。

IllegalStateException异常：数据库已关闭

我的code是如下：

 公共类populatingLectures扩展ListActivity {

私有静态的String [] FROM = {主语，话题，LECTURENUMBER，DATE};
私有静态诠释[] TO = {R.id.subject，R.id.topic，
        R.id.lecturenumber，R.id.date};
私有静态的String []数据= {主语，话题，LECTURENUMBER，_DATA};
私有静态字符串ORDER_BY = DATE +DESC;
私人SoftCopyDatabase讲座;
字符串gotId;


@覆盖
公共无效的onCreate（包savedInstanceState）{
    super.onCreate（savedInstanceState）;
    SoftCopyDatabase讲座=新SoftCopyDatabase（本​​）;
    尝试 {
        光标光标= getLectures（）;
        showLectures（光标）;
    } 最后 {
        lectures.close（）;
    }
}

公共无效的OnStart（）{
    super.onStart（）;
    讲座=新SoftCopyDatabase（本​​）;
    尝试 {
        光标光标= getLectures（）;
        showLectures（光标）;
    } 最后 {
        lectures.close（）;
    }
}

私人光标getLectures（）{

    SQLiteDatabase DB = lectures.getReadableDatabase（）;

    光标光标= db.query（TABLE_NAME，空科目=？，新的String [] {} OpenClick.subjectName，NULL，NULL，
            ORDER_BY）;
    startManagingCursor（光标）;
    返回游标;
}


私人无效showLectures（光标指针）{

    SimpleCursorAdapter适配器=新SimpleCursorAdapter（这一点，
            R.layout.item_lectures，光标，发件人，收件人）;
    setListAdapter（适配器）;
}

私人光标getFileName（字符串ID）{

    SQLiteDatabase DB = lectures.getReadableDatabase（）;
    光标光标= db.query（TABLE_NAME，数据，_ID =？，
            新的String [] {ID}，NULL，NULL，NULL）;
    startManagingCursor（光标）;
    返回游标;
}


@覆盖
保护无效onListItemClick（ListView控件的ListView，视图中查看，INT位置，
        长ID）{
    super.onListItemClick（ListView控件，观点，立场，身份证）;

             //...$c$c TO开始新的活动

    }
}


}
 

请告诉我什么错误，我在做。因为我不是关闭数据库明确任何地方。

问候， Waneya伊克巴尔。

解决方案

 最后
{
 lectures.close（）;
}
 

我觉得这行给出了异常，因此将其放在的onDestroy（）。

I am using SimpleCursorAdapter and database table to populate a List. The list gets populated and I am able to click on list items to open the desired item(This starts a new activity). The problem is when I press the back key, I got Following error.

IllegalStateException: database already closed.

My code is as follows:

public class populatingLectures extends ListActivity{

private static String[] FROM = {SUBJECT, TOPIC, LECTURENUMBER, DATE };
private static int[] TO = {R.id.subject, R.id.topic,
        R.id.lecturenumber, R.id.date };
private static String[] data = { SUBJECT, TOPIC, LECTURENUMBER, _DATA };
private static String ORDER_BY = DATE + " DESC";
private SoftCopyDatabase lectures;  
String gotId;


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    SoftCopyDatabase lectures = new SoftCopyDatabase(this);
    try {
        Cursor cursor = getLectures();
        showLectures(cursor);
    } finally {
        lectures.close();
    }
}

public void onStart() {
    super.onStart();
    lectures = new SoftCopyDatabase(this);
    try {
        Cursor cursor = getLectures();
        showLectures(cursor);
    } finally {
        lectures.close();
    }
}

private Cursor getLectures() {

    SQLiteDatabase db = lectures.getReadableDatabase();

    Cursor cursor = db.query(TABLE_NAME,null, "subject=?", new String[] {OpenClick.subjectName}, null, null,
            ORDER_BY);
    startManagingCursor(cursor);
    return cursor;
}


private void showLectures(Cursor cursor) {

    SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
            R.layout.item_lectures, cursor, FROM, TO);
    setListAdapter(adapter);
}

private Cursor getFileName(String ID) {

    SQLiteDatabase db = lectures.getReadableDatabase();
    Cursor cursor = db.query(TABLE_NAME, data, "_ID=?",
            new String[] { ID }, null, null, null);
    startManagingCursor(cursor);
    return cursor;
}


@Override
protected void onListItemClick(ListView listView, View view, int position,
        long id) {
    super.onListItemClick(listView, view, position, id);

             //...CODE TO START NEW ACTIVITY

    }
}


}

Kindly tell me what mistake am I doing. Because I am not closing the database explicitly any where.

Regards, Waneya Iqbal.

解决方案

finally
{       
 lectures.close();
}

I think this line gives the exception, so put it in onDestroy().

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