Hutool 39 New <SIMPLE>

Hutool 39 New: A Comprehensive Guide to the Latest Breakthroughs in Java Utility Heaven

Example 1: Bulk Image Resizing with Metadata Preservation

// Resize every PNG in a directory, keeping EXIF data
File[] images = FileUtil.ls("/photos");
for (File img : images) 
    ImgUtil.scale(img, FileUtil.file("/thumbnails", img.getName()), 0.5f);
    // New in v39: Preserves orientation using ImageMetadataReader

3.4 core Enhancements

4. Migration from 5.x to 6.x

3.6 Extra Utilities

• NetUtil.ipToLong(), longToIp() (no more manual bit ops).
• ZipUtil.zipStream() for streaming large archives.
• ImageUtil.resize() with better algorithms (Lanczos, etc.).

The One Breaking Change (Sorry!)

StrUtil.subBetween() now returns null (instead of empty string) when the delimiters aren’t found. This aligns with “absent” semantics. A quick grep of your codebase will catch any affected calls.

Example 3: Scheduled Report Generator Using CronUtil

// Run every Monday at 9 AM with virtual thread executor
CronUtil.schedule("0 0 9 ? * MON", "reportJob", () -> 
    try (var exec = ThreadUtil.newVirtualExecutor()) 
        exec.submit(() -> generateDailyReport());
);
CronUtil.setMatchSecond(true);
CronUtil.start();

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