BaseColumns在Android中有什么用 [英] What is the use of BaseColumns in Android

问题描述

在 Android 中从 BaseColumns 实现一个类有什么用?

What is the use of implementing a class from BaseColumns in Android?

推荐答案

这是一个简单的界面，添加了两个字段:

This is a simple interface which adds two fields :

public interface BaseColumns
{
    /**
     * The unique ID for a row.
     * <P>Type: INTEGER (long)</P>
     */
    public static final String _ID = "_id";

    /**
     * The count of rows in a directory.
     * <P>Type: INTEGER</P>
     */
    public static final String _COUNT = "_count";
}

Android 中使用的内部 sqlite 数据库，带有一个 _id 列，该列可自动递增并可用作主键.这也很好地与 ContentProviders

Internally sqlite databases used in Android, comes with an _id column that autoincrements and can function as a primary key. This also maps well with the ContentProviders

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