Java7 / enum constructor / Files.createTempDirectory(String prefix, FileAttribute<?>… attrs)

Question

I'd like to create a Path instance for an enum constructor:

/** Temporary paths. */
public enum PATHS {

    /** First temporary directory. */
    PATH1(Files.createTempDirectory(new StringBuilder("tnk").append(File.separator).append("path1")
            .toString())),
    /** Second temporary directory. */
    PATH2(Files.createTempDirectory(new StringBuilder("tnk").append(File.separator).append("path2")
            .toString()));

    /** {@link Path} reference. */
    final Path mPath;

    /**
     * Constructor.
     * 
     * @param pPath
     *            {@link Path} reference
     */
    PATHS(final Path pPath) {
        mPath = pPath;
    }

    /**
     * Get {@link File} associated with the path.
     * 
     * @return {@link File} reference
     */
    public File getFile() {
        return mPath.toFile();
    }
}

Files.createTempDirectory(String, FilleAttribute<?> atts)throws a checked exception (IOException) but how do I catch or throw the exception or more precisely how do I handle the exception? Seems to be a dump question, but I have no idea right now.

Answer 1

Handle it in the constructor instead.

PATH1("path1"),
PATH2("path2");

final Path mPath;

PATHS(final String path) {
    try {
        mPath = Files.createTempDirectory(new StringBuilder("tnk").append(File.separator).append(path).toString());
    } catch (IOException e) {
        throw new ExceptionInInitializerError(e);
    }
}

Additional benefit is that it also minimizes code duplication in this particular case.

Said that, I'd really think twice about what Tom Hawtin is trying to tell you.

Answer 2

Really anything touching state should not be done with static fields. So simply makes "PATHS" a normal class. Create it once, and endow it to objects that should be using it. The better design should improve error handling, testing, dependency, security, etc.