我如何计算文件的数量与Android的特定扩展名？ [英] How do I count the number of files with a specific extension on Android?

问题描述

在应用程序，我开发的机器人我让用户创建特定的文件到我的扩展名为.rbc应用程序。到目前为止，我已经创建，写入，并从这些文件看是成功的。

In the app I'm developing for Android I'm letting users create files specific to my application with the extension ".rbc". So far I have been successful in creating, writing to, and reading from these files.

现在我想指望这些文件存在的数量。我不是特别熟悉Java，我刚刚开始编程的Andr​​oid让我感到有点失落。我所有的努力，到目前为止，在做这个一直没能找到任何文件，我的分机。

Right now I am trying to count the number of these files that exists. I'm not particularly familiar with Java and I'm just beginning programming for Android so I feel a bit lost. All of my attempts so far at doing this have not been able to locate any files with my extension.

所以，我基本上我需要回答两个问题，这样我可以想出解决办法：

So I basically have two questions I need answered so that I can figure this out:

哪里是哪里的Andr​​oid的文件存储应用程序创建的默认目录？

Where is the default directory where Android stores files created by an application?

你有什么例子你能给与Android的特定扩展名的文件计数的我？

Do you have any examples do you can give me of counting files with a specific extension on Android?

非常感谢你提前为您的时间。

Thank you very much in advance for your time.

推荐答案

一些测试表明我在那里的Andr​​oid存储文件由应用程序使用创建的默认目录 Context.getFilesDir（）是 /数据/数据​​/＆LT; your_package_name＆GT; /文件

Some tests showed me that the default directory where Android stores files created by an application using Context.getFilesDir() is /data/data/<your_package_name>/files

要算在你使用 File.listFiles（的FileFilter）上的根目录，任何给定目录中的文件。那么你的FileFilter应该是这样的（为.rbc文件过滤器）：

To count the files in any given directory you use File.listFiles(FileFilter) over the root dir. Your FileFilter should then be something like this (to filter for ".rbc" files):

public static class RBCFileFilter implements FileFilter {

    @Override
    public boolean accept(File pathname) {
        String suffix = ".rbc";
        if( pathname.getName().toLowerCase().endsWith(suffix) ) {
            return true;
        }
        return false;
    }

}

如果你有某种目录结构需要递归搜索，那么你将不得不 File.listFiles（的FileFilter）在整个目录结构。它应该是这样的：

If you have some kind of directory structure you need to recursively search then you will have to File.listFiles(FileFilter) over the entire directory structure. And it should be something like:

public static List<File> listFiles(File rootDir, FileFilter filter, boolean recursive) {
    List<File> result = new ArrayList<File>();
    if( !rootDir.exists() || !rootDir.isDirectory() ) 
        return result;


    //Add all files that comply with the given filter
    File[] files = rootDir.listFiles(filter);
    for( File f : files) {
        if( !result.contains(f) )
            result.add(f);
    }

    //Recurse through all available dirs if we are scanning recursively
    if( recursive ) {
        File[] dirs = rootDir.listFiles(new DirFilter());
        for( File f : dirs ) {
            if( f.canRead() ) {
                result.addAll(listFiles(f, filter, recursive));
            }
        }
    }

    return result;
}

和其中 DirFilter 将工具的FileFilter 是这样的：

And where DirFilter would implements FileFilter this way:

public static class DirFilter implements FileFilter {

    @Override
    public boolean accept(File pathname) {
        if( pathname.isDirectory() ) 
            return true;

        return false;
    }

}

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