同问

打开IDE，输入Files.readString(...)

按Ctrl点击readString查看源码，追踪到readAllBytes():

    public static byte[] readAllBytes(Path path) throws IOException {
        try (SeekableByteChannel sbc = Files.newByteChannel(path);
             InputStream in = Channels.newInputStream(sbc)) {
            if (sbc instanceof FileChannelImpl)
                ((FileChannelImpl) sbc).setUninterruptible();
            long size = sbc.size();
            if (size > (long) MAX_BUFFER_SIZE)
                throw new OutOfMemoryError("Required array size too large");
            return read(in, (int)size);
        }
    }

看到那个try(resources)了吗？这样心里就有谱了。

try（）

{}

与python的with open()类似