基于SQLite支持的ContentProvider更新ListView [英] Update ListView based on SQLite backed ContentProvider

问题描述

我是一名新的Android开发人员，似乎有点不知所措。当我向列表中添加更多内容时，我试图进行listView更新。

I'm a new Android Developer and seem to have gotten in a little over my head. I am trying to make a listView update when I add more content to the list.

ListView基于SQLite数据库。通过为SQLite数据库创建ContentProvider，我能够使ListView基于SQLite数据库（建议此处）。现在我的问题是我想更新SQLite数据库并将其反映在ListView上。我使用的是加载程序，并且如果我实现了加载程序，则根据此

The ListView is based off of a SQLite database. I was able to get the ListView to be based on the SQLite database by making a ContentProvider for the SQLite database (which was suggested here). Now my issue is that I want to update the SQLite database and have it reflected on the ListView. I am using a loader and according to this if I implemented the loader right it will monitor the data.

我尝试直接更新SQLite数据库，但这并没有导致ListView在不关闭和重新打开的情况下进行更新。我的直觉是，我应该在我的contentProvider中实现insert方法。我做了一个非常简单的实现：

I tried updating the SQLite database directly but, that didn't cause the ListView to update without closing and reopening. My instinct from there is that I should implement the insert method in my contentProvider. I did a very simple implementation:

    @Override
    public Uri insert(Uri uri, ContentValues contentValues) {
        return ContentUris.withAppendedId(uri, mCollectionDB.insertCollection(contentValues));
}

不幸的是，其结果是我的应用程序崩溃了，并带有 java.lang 。空指针异常。这尤其令人困惑，因为使用完全相同的contentValues可以从MainActivity进行.insertCollection调用而没有问题。

Unfortunately, the result of this is my app crashes with a "java.lang.NullPointerException". This is especially confusing as using the exact same contentValues to make the .insertCollection call from my MainActivity works without issue.

我真正感兴趣的问题是如何获取当我将数据插入SQLite数据库时，我的listView会更新。如果插入到ContentProvider中无关紧要，请忽略它。我不太确定哪里出了问题，所以不确定其他什么代码可能有用，但是如果有帮助，我很乐意编辑更多代码。

The issue I'm really interested in is how to get my listView to update when I insert data into my SQLite database. If inserting into the ContentProvider is irrelevant then please ignore that. I'm not really sure where I went wrong so I'm not sure what other code may be useful, but I'm happy to edit in more code if it'll help.

推荐答案

您可以检查加载程序的概念。
您可以从
开始 http：//www.vogella .com / articles / AndroidSQLite / article.html＃todo

You can check loader concept. You can start with http://www.vogella.com/articles/AndroidSQLite/article.html#todo

以下是其他2篇不错的教程
http://mobile.tutsplus.com/tutorials/android/android-sdk_content-providers/

Following are other 2 good tutorials http://mobile.tutsplus.com/tutorials/android/android-sdk_content-providers/

http：// mobile。 tutsplus.com/tutorials/android/android-sdk_loading-data_cursorloader/

这篇关于基于SQLite支持的ContentProvider更新ListView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！