为什么没有在列表＆LT只有一个数据;串＆GT ;? [英] Why there is only one data in the List<String>?

问题描述

我用游标数据库中选择，并希望把所有的数据列表里面，然后返回到在MainActivity。但是，调试完毕后，我发现，只有返回值中的第一个数据。

 公开名单＆LT;串GT;选择1（字符串ReservedState，字符串mycity，字符串mystreet，字符串mypost code）{
    ReservedState =自由;
    SQLiteDatabase数据库1 = dbHelper1.getWritableDatabase（）;
    的String [] =列{DbHelper1.KEY_ID1，DbHelper1.KEY_RESERVEDSTATE，DbHelper1.KEY_GEOGRAPHICALLOCATION，DbHelper1.KEY_CITY，DbHelper1.KEY_POST code，DbHelper1.KEY_STREET};
    光标光标= Database1.query（DbHelper1.TABLE_NAME_1，列DbHelper1.KEY_RESERVEDSTATE +='+ ReservedState +和+ DbHelper1.KEY_CITY +='+ mycity +和+ DbHelper1.KEY_POST code += '+ mypost code +和+ DbHelper1.KEY_STREET +='+ mystreet +'，NULL，NULL，NULL，NULL）;
    // StringBuffer的缓冲区=新的StringBuffer（）;
    清单＆LT;串GT;人=新的ArrayList＆LT;串GT;（）;
    cursor.moveToFirst（）;
    而（！cursor.isAfterLast（））{
        INT索引1 = cursor.getColumnIndex（DbHelper1.KEY_ID1）;
        字符串ID = cursor.getString（指数1）;
        al.add（ID）;
        cursor.moveToNext（）;
    }
    返回人;
 

}

解决方案

 公开名单＆LT;串GT;选择1（字符串ReservedState，字符串mycity，字符串mystreet，字符串mypost code）{
        ReservedState =自由;
        SQLiteDatabase数据库1 = dbHelper1.getWritableDatabase（）;
        的String [] =列{DbHelper1.KEY_ID1，DbHelper1.KEY_RESERVEDSTATE，DbHelper1.KEY_GEOGRAPHICALLOCATION，DbHelper1.KEY_CITY，DbHelper1.KEY_POST code，DbHelper1.KEY_STREET};
        光标光标= Database1.query（DbHelper1.TABLE_NAME_1，列DbHelper1.KEY_RESERVEDSTATE +='+ ReservedState +和+ DbHelper1.KEY_CITY +='+ mycity +和+ DbHelper1.KEY_POST code += '+ mypost code +和+ DbHelper1.KEY_STREET +='+ mystreet +'，NULL，NULL，NULL，NULL）;
        Log.e（光标，+ cursor.getCount（））;
        // StringBuffer的缓冲区=新的StringBuffer（）;
        清单＆LT;串GT;名单=新的ArrayList＆LT;串GT;（）;
        做{
            INT索引1 = cursor.getColumnIndex（DbHelper1.KEY_ID1）;
            字符串ID = cursor.getString（指数1）;
            list.add（ID）;
          }而（cursor.moveToNext（））;
        返回人;
    }
 

试试这个。希望这会有所帮助。

I used cursor for database selecting and want to put all the data inside a List, then return to the mainactivity. But after debugging, I found that there is only the first data inside the return value.

public List<String> select1 (String ReservedState, String mycity, String mystreet, String mypostcode){
    ReservedState="Free";
    SQLiteDatabase Database1=dbHelper1.getWritableDatabase();
    String[] columns={DbHelper1.KEY_ID1,DbHelper1.KEY_RESERVEDSTATE, DbHelper1.KEY_GEOGRAPHICALLOCATION,DbHelper1.KEY_CITY,DbHelper1.KEY_POSTCODE,DbHelper1.KEY_STREET};
    Cursor cursor=Database1.query(DbHelper1.TABLE_NAME_1,columns, DbHelper1.KEY_RESERVEDSTATE+"='"+ReservedState+"' AND "+DbHelper1.KEY_CITY+"='"+mycity+"' AND "+DbHelper1.KEY_POSTCODE+"='"+mypostcode+"' AND "+DbHelper1.KEY_STREET+"='"+mystreet+"'",null,null,null,null);
    //StringBuffer buffer=new StringBuffer();
    List<String> al=new ArrayList<String>();
    cursor.moveToFirst();
    while(!cursor.isAfterLast()){
        int index1=cursor.getColumnIndex(DbHelper1.KEY_ID1);
        String id=cursor.getString(index1);
        al.add(id);
        cursor.moveToNext();
    }
    return al;

}

解决方案

public List<String> select1 (String ReservedState, String mycity, String mystreet, String mypostcode){
        ReservedState="Free";
        SQLiteDatabase Database1=dbHelper1.getWritableDatabase();
        String[] columns={DbHelper1.KEY_ID1,DbHelper1.KEY_RESERVEDSTATE, DbHelper1.KEY_GEOGRAPHICALLOCATION,DbHelper1.KEY_CITY,DbHelper1.KEY_POSTCODE,DbHelper1.KEY_STREET};
        Cursor cursor=Database1.query(DbHelper1.TABLE_NAME_1,columns, DbHelper1.KEY_RESERVEDSTATE+"='"+ReservedState+"' AND "+DbHelper1.KEY_CITY+"='"+mycity+"' AND "+DbHelper1.KEY_POSTCODE+"='"+mypostcode+"' AND "+DbHelper1.KEY_STREET+"='"+mystreet+"'",null,null,null,null);
        Log.e("Cursor",""+cursor.getCount());
        //StringBuffer buffer=new StringBuffer();
        List<String> list=new ArrayList<String>();
        do{
            int index1=cursor.getColumnIndex(DbHelper1.KEY_ID1);
            String id=cursor.getString(index1);
            list.add(id);
          }while(cursor.moveToNext());
        return al;
    }

Try this. Hope this will help.

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