How to Calculate the Size of a File or Folder in Java?

Calculating File and Folder Size in Java

Determining the size of files and folders is a fundamental task in programming. Java provides convenient methods for retrieving this information.

Retrieving File Size

To obtain the size of a file, utilize the File class:

<code class="java">java.io.File file = new java.io.File("myfile.txt");
long fileSize = file.length();</code>

This method returns the file size in bytes or 0 if the file doesn't exist.

Calculating Folder Size

Java doesn't provide a direct mechanism for determining the size of a folder. To accomplish this, we can recursively traverse the directory tree using the listFiles() method. Here's a sample function:

<code class="java">public static long folderSize(File directory) {
    long size = 0;
    for (File file : directory.listFiles()) {
        if (file.isFile())
            size += file.length();
        else
            size += folderSize(file);
    }
    return size;
}</code>

This function calculates the folder size by recursively adding the sizes of its files and subfolders.

Caution:

Note that the folderSize() method has limitations. It may encounter null references from listFiles() and overlook symlinks. For reliable results, consider using a robust implementation designed for production use.

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