在Android上过滤目录中的文件

Question

In my app i am getting the images from a folder in gallery and saving it into an array list.Now i want to extract only the files with .jpg extension.How can i do it

The code for saving to array list is

  private List<String> ReadSDCard()
    {
     //It have to be matched with the directory in SDCard
     File f = new File("sdcard/data/crak");

     File[] files=f.listFiles();

     for(int i=0; i<files.length; i++)
     {
      File file = files[i];
      /*It's assumed that all file in the path are in supported type*/
      tFileList.add(file.getPath());
     }
     return tFileList;
    }

Answer 1

You can use FilenameFilter interface to Filter the Files.

Change your codeline

File[] files=f.listFiles();

as below:

File[] jpgfiles = f.listFiles(new FileFilter() {
            @Override
            public boolean accept(File file)
            {
                return (file.getPath().endsWith(".jpg")||file.getPath().endsWith(".jpeg"));
            }
});

Answer 2

Use .endsWith() method from Java String Class to check File Extension from file path.

Method:

public boolean endsWith(String suffix)

Your Code something like,

private List<String> ReadSDCard()
{
     //It have to be matched with the directory in SDCard
     File f = new File("sdcard/data/crak");

     File[] files=f.listFiles();

     for(int i=0; i<files.length; i++)
     {
      File file = files[i];
      /*It's assumed that all file in the path are in supported type*/
      String filePath = file.getPath();
      if(filePath.endsWith(".jpg")) // Condition to check .jpg file extension
      tFileList.add(filePath);
     }
 return tFileList;
}

Answer 3

private List<String> ReadSDCard()
{

    String extension = "";
    File f = new File("sdcard/data/crak");

    File[] files=f.listFiles();

     for(int i=0; i<files.length; i++)
     {

         File file = files[i];
         int ind = files[i].getPath().lastIndexOf('.');
         if (ind > 0) {
             extension = files[i].getPath().substring(i+1);// this is the extension
             if(extension.equals("jpg"))
             {
                 tFileList.add(file.getPath());
             }
         }
     }
 return tFileList;
}

Answer 4

In your code add the following:

          String filePath = file.getPath();
          if(filePath.endsWith(".jpg")) 
          tFileList.add(filePath);