Java 如何在Android中修复带有光标数据的列表数组

嗨，我用SQL在android上创建了一个应用程序。我在设置光标时遇到问题。我不知道我做错了什么，因为这是我第一个使用带游标的数组列表的程序。谢谢你的帮助

public class ThoughtManager {

private Thought thought;
private ThoughtDbHelper dbHelper;
private Cursor cursor;
private Context context;

SQLiteDatabase db;
private ContentValues contentValues;
private ArrayList<Thought> allThoughts;
int iTitle;
int iDetail;
int iTime;
int iDate;
int iReason;
int iComment;

private String[] columns=new String[]{ThoughtDbHelper.KEY,
        ThoughtDbHelper.TITLE,
        ThoughtDbHelper.DETAIL,
        ThoughtDbHelper.TIME,
        ThoughtDbHelper.DATE,
        ThoughtDbHelper.REASON,
        ThoughtDbHelper.COMMENT}; // Tablica wypisywanych elementow

public ThoughtManager(Context context)
{
    this.context = context;        // CO tu dokładnie robimy????
    dbHelper=new ThoughtDbHelper(context);
    contentValues=new ContentValues();
}

public ThoughtManager openForWrite() // Gdy chcemy zapisywac cos w bazie nowego
{
    db=dbHelper.getWritableDatabase();
    return  this;
}
public ThoughtManager openForRead() // Gdy chcemy odczytywac dane z bazy
{
    db=dbHelper.getReadableDatabase();
    return  this;
}
public void close()
{
    dbHelper.close(); // Bezpieczne zamykanie aplikacji
}

public long createThought(Thought thought)  // TWORZE NOWY ELEMENT W BAZIE DANYCH!!!
{
    contentValues.put(ThoughtDbHelper.TITLE, thought.getTitle());
    contentValues.put(ThoughtDbHelper.DETAIL, thought.getDetails());
    contentValues.put(ThoughtDbHelper.TIME, thought.getTime());
    contentValues.put(ThoughtDbHelper.DATE, thought.getDate());
    contentValues.put(ThoughtDbHelper.REASON, thought.getReason());
    contentValues.put(ThoughtDbHelper.COMMENT, thought.getComment());

    return db.insert(ThoughtDbHelper.TABLE_NAME, null, contentValues);
}
public int updateThought(Thought thought) // Edytuje element W BAZIE DANYCH!!!
{
    contentValues.put(ThoughtDbHelper.TITLE, thought.getTitle());
    contentValues.put(ThoughtDbHelper.DETAIL, thought.getDetails());
    contentValues.put(ThoughtDbHelper.TIME, thought.getTime());
    contentValues.put(ThoughtDbHelper.DATE, thought.getDate());
    contentValues.put(ThoughtDbHelper.REASON, thought.getReason());
    contentValues.put(ThoughtDbHelper.COMMENT, thought.getComment());
    return db.update(ThoughtDbHelper.TABLE_NAME, contentValues, ThoughtDbHelper.TITLE + "=" + thought.getTitle(), null);
}
public int deleteThought(Thought thought) // Usuwa element W BAZIE DANYCH!!!
{
    return db.delete(ThoughtDbHelper.TABLE_NAME, ThoughtDbHelper.TITLE + "=" + thought.getTitle(), null);
}

public ArrayList<Thought> getAllThoughts() // Pobieramy wszystkie elementy do tablicy
{

    //Cursor cursor=db.query(ThoughtDbHelper.TABLE_NAME, columns, null,null,null,null,null);
    //cursor.moveToFirst();
    cursor = db.query(ThoughtDbHelper.TABLE_NAME, new String[]{ThoughtDbHelper.KEY,
            ThoughtDbHelper.TITLE,
            ThoughtDbHelper.DETAIL,
            ThoughtDbHelper.TIME,
            ThoughtDbHelper.DATE,
            ThoughtDbHelper.REASON,
            ThoughtDbHelper.COMMENT}, (String)null, (String[])null, (String)null, (String)null, (String)null);

    iTitle = cursor.getColumnIndex(ThoughtDbHelper.TITLE);
    iDetail=cursor.getColumnIndex(ThoughtDbHelper.DETAIL);
    iTime=cursor.getColumnIndex(ThoughtDbHelper.TIME);
    iDate=cursor.getColumnIndex(ThoughtDbHelper.DATE);
    iReason=cursor.getColumnIndex(ThoughtDbHelper.REASON);
    iComment=cursor.getColumnIndex(ThoughtDbHelper.COMMENT);
    // W petli wpisuje kolejno wszystkie dane do kolejnych tablic w zlaeznosic ile mamy elemetow
    for(cursor.moveToFirst();!cursor.isAfterLast();cursor.moveToNext()) // (zacznij od poczatku ; rózny(!) od ostatniego ; idz co jeden
    {
        thought=new Thought(cursor.getString(iTitle),  // pobieram tytul
                cursor.getString(iDetail), // poberam opis
                cursor.getString(iReason), // pobierma czas etc...
                cursor.getString(iComment),
                cursor.getString(iDate),
                cursor.getString(iTime));
        allThoughts.add(thought);
    }
    return  allThoughts;
}

public Thought getThought(Thought thought)
{
    cursor=db.query(ThoughtDbHelper.TABLE_NAME, columns, null, null, null, null, null);
    iTitle=cursor.getColumnIndex(ThoughtDbHelper.TITLE);
    iDetail=cursor.getColumnIndex(ThoughtDbHelper.DETAIL);
    iTime=cursor.getColumnIndex(ThoughtDbHelper.TIME);
    iDate=cursor.getColumnIndex(ThoughtDbHelper.DATE);
    iReason=cursor.getColumnIndex(ThoughtDbHelper.REASON);
    iComment=cursor.getColumnIndex(ThoughtDbHelper.COMMENT);
    if(cursor!=null) // Jezeli mamy jakies dane
    {
        cursor.moveToFirst(); // przerzuc kursor do poczatku, by odczytywac dane od 1
        thought=new Thought(cursor.getString(iTitle),  // pobieram tytul
                cursor.getString(iDetail), // posberam opis
                cursor.getString(iReason), // pobierma czas etc...
                cursor.getString(iComment),
                cursor.getString(iDate),
                cursor.getString(iTime));
        allThoughts.add(thought);
    }
    return thought;
}

查看想法：在那里我想查看我保存的想法

public class ViewThought extends ListActivity {

ThoughtManager manager;
ArrayList<Thought> allThoughts;
ArrayList<String> allTitles;
ListView listView;
Thought thought;
String titlePosition;
Dialog dialog;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
   // setContentView(R.layout.view_thought);
    manager=new ThoughtManager(this);
    allTitles = new ArrayList<String>();
    listView = getListView();
    //listView.setBackgroundResource();
    listView.setPadding(10, 20, 10, 15);
    listView.setFooterDividersEnabled(true);
    listView.setHeaderDividersEnabled(true);
    d
    allThoughts = manager.getAllThoughts();

    // Pobieram wszystkie zadania/notatki
    for (Thought thought : allThoughts) // od  d ostatniego elemetnu
    {
        allTitles.add(thought.getTitle());
    }
    listView.setAdapter(new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1 ,allTitles));
}

@Override
protected void onListItemClick(ListView l, View v, int position, long id) {

    super.onListItemClick(l, v, position, id);
 /*   titlePosition = allTitles.get(position);
    //thought=manager.getThought(titlePosition);

    dialog=new Dialog(ViewThought.this);
    dialog.setContentView(R.layout.view_details);
    // 1 sposob
    //dialog.setTitle("Thought Detail view");

    //2 sposob
    TextView tvTime,tvDetail,tvReason,tvComment;
    tvComment=(TextView) dialog.findViewById(R.id.tvViewComment);
    tvDetail=(TextView) dialog.findViewById(R.id.tvViewDetails);
    tvReason=(TextView) dialog.findViewById(R.id.tvViewReason);
    tvTime=(TextView) dialog.findViewById(R.id.tvViewTime);

    dialog.setTitle(thought.getTitle()); 
    tvComment.setText(thought.getComment());
    tvDetail.setText(thought.getDetails());
    tvReason.setText(thought.getReason());
    tvTime.setText("Created on"+thought.getDate()+"At "+thought.getTime()); 
    dialog.show();

    */

  }
}

公共类视图扩展了ListActivity{
思想经理人；
所有思想；
arraylistalltitles；
列表视图列表视图；
思维；
字符串标题位置；
对话；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
//setContentView（R.layout.view\u思想）；
管理者=新思维管理者（本）；
allTitles=新的ArrayList（）；
listView=getListView（）；
//listView.setBackgroundResource（）；
setPadding（10,20,10,15）；
setFooterDividerEnabled（true）；
setHeaderDivisEnabled（true）；
D
AllThinks=manager.getAllThinks（）；
//Pobieram wszystkie zadania/notatki
（思想思想：所有思想）//od d ostatniego elemetnu
{
allTitles.add（think.getTitle（））；
}
setAdapter（新的ArrayAdapter（此，
android.R.layout.simple_list_item_1，allTitles））；
}
@凌驾
受保护的void onListItemClick（列表视图l、视图v、整数位置、长id）{
super.onListItemClick（左、右、位置、id）；
/*titlePosition=allTitles.get（位置）；
//思想=管理者。思考（标题位置）；
dialog=新建对话框（viewThink.this）；
对话框.setContentView（R.layout.view\u详细信息）；
//1 sposob
//setTitle（“思想细节视图”）；
//2 sposob
text查看电视时间、电视详情、电视原因、电视评论；
TVComent=（TextView）dialog.findViewById（R.id.tvViewComment）；
tvDetail=（TextView）dialog.findViewById（R.id.tvViewDetails）；
tvReason=（TextView）dialog.findViewById（R.id.tvViewReason）；
tvTime=（TextView）dialog.findViewById（R.id.TVTViewTime）；
setTitle（think.getTitle（））；
tvecomment.setText（think.getComment（））；
tvDetail.setText（think.getDetails（））；
tvReason.setText（think.getReason（））；
setText（“在”+think.getTime（）处的“+think.getDate（）+”上创建）；
dialog.show（）；
*/
}
}

查看完整的演练

您需要初始化数据库，如：

SQLiteDatabase db = mDbHelper.getReadableDatabase();

---

在你读到任何东西之前。

怎么了？您的确切问题、期望是什么，您有什么..？我有一个错误：java.lang.NullPointerException.Where？发布你的logcat。调试程序告诉我，问题在于游标。如果可能的话，我也可以显示我的所有项目。你对getReadableDatabase（）有什么看法？根据官方教程（按照上面的链接！），你需要一个，这将为你提供一个数据库。我添加了我的所有ThoughtManager代码，你可以再看一次吗。我将非常感激，因为它仍然不起作用。我会解决这个问题。现在我有另一个；/当我想把想法添加到数组列表中时，我有错误，你能看看我做错了什么吗？代码与我的第一个问题相同。

SQLiteDatabase db = mDbHelper.getReadableDatabase();