Asked  7 Months ago    Answers:  5   Viewed   28 times

In the App Engine docs, what is the ellipsis (JID...) for in this method signature?

public MessageBuilder withRecipientJids(JID... recipientJids)

What's the function of those three dots?



Those are Java varargs. They let you pass any number of objects of a specific type (in this case they are of type JID).

In your example, the following function calls would be valid:

MessageBuilder msgBuilder; //There should probably be a call to a constructor here ;)
MessageBuilder msgBuilder2;
msgBuilder.withRecipientJids(jid1, jid2);
msgBuilder2.withRecipientJids(jid1, jid2, jid78_a, someOtherJid);

See more here:

Tuesday, June 1, 2021
answered 7 Months ago

I like the idea of letting "thin" characters count as half a character. Simple and a good approximation.

The main issue with most ellipsizings however, are (imho) that they chop of words in the middle. Here is a solution taking word-boundaries into account (but does not dive into pixel-math and the Swing-API).

private final static String NON_THIN = "[^iIl1\.,']";

private static int textWidth(String str) {
    return (int) (str.length() - str.replaceAll(NON_THIN, "").length() / 2);

public static String ellipsize(String text, int max) {

    if (textWidth(text) <= max)
        return text;

    // Start by chopping off at the word before max
    // This is an over-approximation due to thin-characters...
    int end = text.lastIndexOf(' ', max - 3);

    // Just one long word. Chop it off.
    if (end == -1)
        return text.substring(0, max-3) + "...";

    // Step forward as long as textWidth allows.
    int newEnd = end;
    do {
        end = newEnd;
        newEnd = text.indexOf(' ', end + 1);

        // No more spaces.
        if (newEnd == -1)
            newEnd = text.length();

    } while (textWidth(text.substring(0, newEnd) + "...") < max);

    return text.substring(0, end) + "...";

A test of the algorithm looks like this:

enter image description here

Saturday, June 5, 2021
answered 6 Months ago

You could try to use a ValueConverter (cf. IValueConverter interface) to change the strings that should be displayed in the list box yourself. That is, in the implementation of the Convert method, you would test if the strings are longer than the available space, and then change them to ... plus the right side of the string.

Friday, July 23, 2021
answered 5 Months ago

Generally, this means a copy of this. The thing about this is that it changes within each function. Storing it this way, however, keeps $this from changing whereas this does change.

jQuery heavily uses the magic this value.

Consider this code, where you might need something like you are seeing:

$.fn.doSomethingWithElements = function() {
    var $this = this;

    this.each(function() {
        // `this` refers to each element and differs each time this function
        //    is called
        // `$this` refers to old `this`, i.e. the set of elements, and will be
        //    the same each time this function is called
Monday, August 2, 2021
answered 4 Months ago

This routine, as a whole, is, effectively, O(m) time complexity, with m being the number of strings in your search.

This is because Dictionary.Contains and Dictionary.Add are both (normally) O(1) operations.

(It's slightly more complicated than that, as Dictionary.Add can be O(n) for n items in the Dictionary, but only when the dictionary capacity is small. As such, if you construct your dictionary with a large enough capacity up front, it would be O(m) for m string entries.)

That being said, if you're only using the Dictionary for existence checking, you could use a HashSet<string>. This would allow you to write:

  public void DistinctWords(String s)
     HashSet<string> hash = new HashSet<string>(s.Split(' '));

     // Use hash here...

As your dictionary is a local variable, and not stored (at least in your code), you could also use LINQ:

 var distinctWords = s.Split(' ').Distinct();
Friday, August 13, 2021
answered 4 Months ago
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