找一个ListView中的项的位置？ [英] Get position of an item within a ListView?

问题描述

一个人怎么会找到一个特定项目的ListView控件中的位置？ （由SimpleCursorAdapter填充）。

How would one find the position of a specific item within a ListView? (Populated by SimpleCursorAdapter).

我之所以问：ListView控件设置为singleChoice模式。当用户关闭并重新打开应用程序，我想用户的选择被人记住。

The reason I ask: The listview is set to singleChoice mode. When the user closes and reopens the app, I'd like the user's selection to be remembered.

就是我已经做到了，到目前为止是当用户点击一个项目，所选项目的ID被保存到preferences。我需要学习的是如何重新选择的项目在活动的onCreate方法，一旦它被重新填充。

The way I've done it so far is when the user clicks on an item, the ID of the chosen item is saved to preferences. What I need to learn is how to reselect the item in the activity's onCreate method once it's been repopulated.

我的code保存所选项目的ID：

My code for saving the selected item's ID:

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

    Cursor c = (Cursor) l.getItemAtPosition(position);
    selectedItem = c.getLong(c.getColumnIndex("_id"));
}

（我试过在Google上搜寻，但只能似乎找到如何获得的位置选择的项目）

谢谢！

推荐答案

您应该尝试

//SimpleCursorAdapter adapter;
final int position = adapter.getCursor().getPosition();

API文档：

public abstract int getPosition () 

自：API级别1

返回的当前位置   在游标的行集。该值是   从零开始的。当行集是第一   返回的光标将在当前位置   -1，这是第一行之前。返回的最后一行之后的另一   来电下一个（）将离开光标   过去的最后一个条目，在一个位置   计数（）。

Returns the current position of the cursor in the row set. The value is zero-based. When the row set is first returned the cursor will be at positon -1, which is before the first row. After the last row is returned another call to next() will leave the cursor past the last entry, at a position of count().

返回 当前光标位置。

更新

要获得基于适配器使用该ID的项目的位置：

To get an item's position based on the id used by the adapter:

private int getItemPositionByAdapterId(final long id)
{
    for (int i = 0; i < adapter.getCount(); i++)
    {
        if (adapter.getItemId(i) == id)
            return i;
    }
    return -1;
}

要获得基于基本对象的属性项目的位置（成员值）

To get an item's position based on the underlying object's properties (member values)

//here i use `id`, which i assume is a member of a `MyObject` class, 
//and this class is used to represent the data of the items inside your list:
private int getItemPositionByObjectId(final long id)
{
    for (int i = 0; i < adapter.getCount(); i++)
    {
        if (((MyObject)adapter.getItem(i)).getId() == id)
            return i;
    }
    return -1;
}

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