Question

我在数据库类中使用以下方法。它不起作用，我看不出问题出在哪里。也许有人可以帮助我。

public ArrayList<Profile> getAllProfile() {

        db = this.getWritableDatabase();
        Profile profile = new Profile();
        Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_USER, null);
        ArrayList<Profile> profiles = new ArrayList<>();

        if (cursor!=null){
            for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext() ){

                profile.setId(cursor.getInt(cursor.getColumnIndex(ID)));
                profile.setFirstName(cursor.getString(cursor.getColumnIndex(FIRST_NAME)));
                profile.setLastName(cursor.getString(cursor.getColumnIndex(LAST_NAME)));
                profile.setFatherName(cursor.getString(cursor.getColumnIndex(FATHER)));
                profile.setAge(cursor.getInt(cursor.getColumnIndex(AGE)));
                profile.setEmail(cursor.getString(cursor.getColumnIndex(EMAIL)));
                profile.setGender(cursor.getInt(cursor.getColumnIndex(GENDER)));
                profile.setPhoneNumber(cursor.getString(cursor.getColumnIndex(PHONE_NUMBER)));
                profiles.add(profile);
                App.myLog("is : " +profile.getFirstName());
            }
            cursor.close();
            return profiles;
        }
        cursor.close();
        return null;
    }

Answer 1

问题似乎是，您在循环之前仅创建Profile对象的一个实例，并且仅将此实例添加到循环中的列表中。

因此，请如下更改代码：

public ArrayList getAllProfile() 
    {
        db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_USER, null);

        if (cursor != null)
        {
            ArrayList<Profile> profiles = new ArrayList<>();

            for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext() )
            {
                Profile profile = new Profile(); // create a new instance in your loop, instead only creating one instance before the loop
                profile.setId(cursor.getInt(cursor.getColumnIndex(ID)));
                profile.setFirstName(cursor.getString(cursor.getColumnIndex(FIRST_NAME)));
                profile.setLastName(cursor.getString(cursor.getColumnIndex(LAST_NAME)));
                profile.setFatherName(cursor.getString(cursor.getColumnIndex(FATHER)));
                profile.setAge(cursor.getInt(cursor.getColumnIndex(AGE)));
                profile.setEmail(cursor.getString(cursor.getColumnIndex(EMAIL)));
                profile.setGender(cursor.getInt(cursor.getColumnIndex(GENDER)));
                profile.setPhoneNumber(cursor.getString(cursor.getColumnIndex(PHONE_NUMBER)));
                profiles.add(profile);
                App.myLog("is : " +profile.getFirstName());
            }
            cursor.close();
            return profiles;
        }

        if(cursor != null)
        {
            cursor.close();
            return null;
        }
    }

如何在for循环中添加arraylist？

1 个答案: