Java 25 Update: Major Changes to Windows File Operations

Heads up, Java devs! 🚨 Java 25 is changing Windows file operation behaviors. Important updates on File.delete and more! #Java25 #Windows #FileOperations

Explanation in video

Big News for Java Users on Windows: A Simple Guide to Upcoming File Changes in Java 25!

Hey everyone, John here! Welcome back to the blog where we break down the latest tech news into plain, simple English. Today, we’ve got some interesting updates from the world of Java – that’s a super popular programming language that powers a ton of apps and websites you probably use every day. Specifically, we’re looking at some changes coming in Java 25 that will affect how Java programs handle files on Windows computers. Don’t worry, it’s not as scary as it sounds, and I’ve got my trusty assistant Lila here to help ask the questions you might be thinking!

Lila: “Hi John! So, Java is changing how it deals with files on Windows? Why are they doing that?”

John: “Great question to kick things off, Lila! The folks at Oracle, who look after Java, are doing what they call a ‘quality outreach.’ Think of it like a car company fine-tuning an engine to make it run smoother and more reliably. These changes are designed to make Java behave more consistently and predictably on Windows, which is a good thing for everyone who builds or uses Java applications.”

Change #1: Deleting “Read-Only” Files Just Got Stricter

Okay, let’s dive into the first main change. It’s all about how Java’s File.delete command (that’s the instruction Java uses to delete a file) handles files that are marked as “read-only” on Windows.

Lila: “John, hold on a sec. What exactly is a ‘read-only’ file?”

John: “Excellent question, Lila! Imagine you have a very important document, like your original birth certificate. You wouldn’t want anyone to accidentally write on it or tear it, right? You might keep it in a protective sleeve. A ‘read-only’ file on a computer is similar. It’s a file that has a special digital flag set on it, telling the computer, ‘Hey, you can look at this, you can copy this, but please don’t change or delete it easily.’ It’s a way to protect important files from accidental modification.”

Lila: “And the article mentioned something about a ‘DOS read-only attribute’. What’s that?”

John: “Good catch! ‘DOS’ was an older operating system that came before modern Windows, but some of its ways of doing things still linger. The ‘read-only attribute’ is just the technical term for that digital flag or marker that Windows uses to identify a file as read-only. So, it’s the specific ‘switch’ that’s flipped to make a file read-only.”

John: “So, here’s what’s changing:

• Before Java 25 (The Old Way): If a Java program tried to delete a read-only file on Windows, Java was quite clever. It would first try to remove that ‘read-only’ flag and then delete the file.
• The Problem with the Old Way: This two-step process (remove flag, then delete) wasn’t what we call an ‘atomic operation.’

Lila: “Whoa, ‘atomic operation’? That sounds like something out of a superhero movie! What does it mean in computer terms?”

John: “Haha, it does sound dramatic! In the computer world, an atomic operation is an action that happens completely and indivisibly, or not at all. Think of flipping a light switch – the light is either fully on or fully off; it can’t get stuck halfway (well, usually!). The old Java way of deleting read-only files wasn’t atomic. It was possible for the first step (removing the read-only flag) to succeed, but then something could go wrong before the second step (deleting the file). This could leave the file in a weird state – no longer read-only, but still there. Not ideal!”

John: “So, here’s the new approach:

• With Java 25 (The New Way): The File.delete command will now simply fail if it tries to delete a file that has the read-only flag set. It will return a ‘false’ signal to the program, basically saying, ‘Nope, couldn’t delete that, it’s read-only.’ This is much more straightforward and predictable.”

Lila: “So, if a programmer really needs their Java program to delete a read-only file in Java 25, are they out of luck?”

John: “Not at all! The Java team has provided a couple of options:

• The Recommended Way: Programmers should update their applications to first explicitly remove the read-only attribute from the file, and then try to delete it. This makes the intention very clear in the code.
• The ‘Old Behavior’ Switch: For a transition period, or for specific needs, there’s a special setting (called a ‘system property’) that programmers can use when they run their Java application: -Djdk.io.File.allowDeleteReadOnlyFiles=true. Using this switch tells Java 25 to behave like it used to – remove the read-only flag before attempting deletion. But generally, the first option is preferred for new code.”

Change #2: No More Sneaky Spaces at the End of File or Directory Names!

The second big change in Java 25 for Windows users is about how Java handles file or directory names that have a space at the very end.

Lila: “A space at the end of a file name? Like ‘My Report .txt’ instead of ‘My Report.txt’?”

John: “Exactly, Lila! That space at the very end is called a ‘trailing space.’ You often can’t even see it, which makes it tricky. The thing is, Windows itself generally doesn’t like file or folder names that end with a space (or a period, for that matter). It considers them ‘illegal’ names. If you try to create a folder named ‘My Stuff ‘ (with a space at the end) using Windows Explorer, Windows will usually automatically remove that space or stop you.”

Lila: “So, what was Java doing before, and what’s changing?”

John: “Here’s the breakdown:

• Before Java 25 (The Old Way): If a Java program tried to work with a file or directory path that included a name with a trailing space (for example, trying to create a folder named ‘Holiday Photos ‘), the behavior could be inconsistent. Sometimes it might seem to work, but it actually hadn’t, or it might behave in other unexpected ways. This could be really confusing for programmers trying to figure out what went wrong.
• With Java 25 (The New Way): Things are much clearer. File operations on a path that includes a directory or file name with a trailing space will now fail consistently on Windows. For example:
  • If a program tries to create a directory with such a name using the File::mkdir command, this command will now reliably return ‘false’ (meaning, ‘I couldn’t do it’).
  • If a program tries to create a new file with such a name using File::createNewFile, it will now throw an ‘IOException’.

Lila: “Okay, File::mkdir sounds like ‘make directory,’ which I guess means ‘make folder.’ But what’s an ‘IOException’?”

John: “You got it, mkdir is indeed for making directories or folders! An IOException stands for ‘Input/Output Exception.’ It’s like Java raising a big red flag and saying, ‘Hey, there’s a problem with reading or writing data here!’ In this case, it’s because the file name isn’t valid on Windows. By ‘throwing an exception,’ Java clearly signals to the program that something went wrong and why, so the programmer can handle the error properly, instead of the program just silently failing or acting weirdly.”

Lila: “The original article also mentioned ‘illegal abstract path name.’ That sounds complicated.”

John: “Let’s break that down. A ‘path name’ is like the full address of a file or folder on your computer, such as C:\Users\YourName\Documents\MyFile.txt. An ‘abstract path name’ is how Java represents these file paths in a way that can work across different operating systems (like Windows, Mac, or Linux). If this ‘address’ contains an element (like a folder name or the file name itself) that’s not allowed by the operating system – in this case, a name with a trailing space on Windows – then it’s an ‘illegal’ path name. Java 25 is now stricter about not letting these illegal names cause confusion.”

Why Are These Changes Happening? It’s All About Quality!

As we mentioned earlier, these updates are part of Oracle’s “quality outreach.” The goal is to make Java more robust, reliable, and predictable, especially when interacting with the specific rules of an operating system like Windows.

Lila: “So, it’s like Java is learning to follow the ‘house rules’ of Windows more closely?”

John: “That’s a perfect way to put it, Lila! By making sure Java behaves consistently with how Windows expects files and directories to be handled, it reduces the chances of unexpected errors and makes life easier for developers who write Java programs that run on Windows. Fewer surprises mean more stable and reliable software for everyone.”

When Can We Expect Java 25?

These changes are slated to arrive with JDK 25 (Java Development Kit 25), which is scheduled for general availability on September 16th. An interesting point is that JDK 25 is also a Long-Term Support (LTS) release.

Lila: “JDK? LTS? More acronyms, John!”

John: “Haha, the tech world loves its acronyms!

• JDK stands for Java Development Kit. It’s the full package that developers use to create Java applications. It includes tools to write, test, and run Java code.
• LTS stands for Long-Term Support. Think of software versions like fashion. Some are trendy and new but might be replaced by another new trend quickly. An LTS release, however, is like a classic, well-made coat. It’s designed to be supported by Oracle with updates and security patches for a much longer period (several years). Many businesses prefer to use LTS versions for their important applications because they offer more stability and a longer lifespan of support, meaning they don’t have to upgrade so frequently.”

A Few Final Thoughts

John: From my perspective as someone who’s seen Java evolve over the years, these kinds of refinements are always welcome. They might seem like small details, but making file operations more predictable and aligned with the host operating system (like Windows) just makes for a smoother experience for developers. It helps prevent those frustrating bugs that can be hard to track down.

Lila: As a beginner, it actually makes a lot of sense to me! If the computer program clearly says, “Nope, you can’t do that because the file is read-only,” or “That file name isn’t allowed,” it seems much easier to understand and fix than if it just did something weird or nothing at all. So, more clarity is definitely good!

John: “Couldn’t agree more, Lila! Clearer rules and more predictable behavior are always a plus in the world of technology.”

This article is based on the following original source, summarized from the author’s perspective:
Java 25 to change Windows file operation behaviors