使用 Cursor 获取字段值 [英] Get the field value with a Cursor

问题描述

我正在创建一个应用程序，但我在使用 Cursor 时遇到了问题.我有一个 SQLiteDatabase，当我尝试使用此函数获取值时，它会返回一个 Cursor:

I'm creating an application and I have problems with Cursor. I have an SQLiteDatabase that returns me a Cursor when I try to fetch the values with this function:

public Cursor fetchOption(long rowId) throws SQLException {

    Cursor mCursor = mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
        KEY_TITLE, KEY_BODY}, KEY_ROWID + "=" + rowId, null,
        null, null, null, null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;

}

我不知道如何获取Cursor中字段的值.如果我这样做:

I don't know how to obtain the value of the field in the Cursor. If I do that like so:

String a = mOptionDb.fetchOption(0).getColumnName(0).toString();
String b = mOptionDb.fetchOption(0).getColumnName(1).toString();
String c = mOptionDb.fetchOption(0).getColumnName(2).toString();

我只获取列的名称(_id, title, body)而不是值.有关如何实现这一目标的任何建议?

I only obtain the name of the columns (_id, title, body) but not the values. Any suggestions on how to achieve this?

推荐答案

我认为您可以忘记检查 null.

I think you can forget about checking for null.

改为检查是否有数据，然后使用游标访问列:

Instead check if there is data and then access the columns using the cursor:

Cursor cursor = fetchOption(0);

if (cursor.moveToFirst()) // data?
   System.out.println(cursor.getString(cursor.getColumnIndex("title")); 

cursor.close(); // that's important too, otherwise you're gonna leak cursors

阅读 Android 教程也可能有意义.记事本教程似乎符合要求:http://developer.android.com/指南/教程/notepad/index.html

It might also make sense to read an Android tutorial. The notepad tutorial seems to fit the bill: http://developer.android.com/guide/tutorials/notepad/index.html

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