CODEWITHSUNDEEP
java
TofuBeer
TofuBeer

Reputation: 61526

Dynamically formatting a string

Before I wander off and roll my own I was wondering if anyone knows of a way to do the following sort of thing...

Currently I am using MessageFormat to create some strings. I now have the requirement that some of those strings will have a variable number of arguments.

For example (current code):

MessageFormat.format("{0} OR {1}", array[0], array[1]);

Now I need something like:

// s will have "1 OR 2 OR 3"
String s = format(new int[] { 1, 2, 3 });

and:

// s will have "1 OR 2 OR 3 OR 4"
String s = format(new int[] { 1, 2, 3, 4 });

There are a couple ways I can think of creating the format string, such as having 1 String per number of arguments (there is a finite number of them so this is practical, but seems bad), or build the string dynamically (there are a lot of them so this could be slow).

Any other suggestions?

Upvotes: 6

Views: 2919

Answers (4)

Satya
Satya

Reputation: 8346

You can use the String#join method from Java 8 and onwards, which will allow you to join strings with the given delimiter.

String.join(" OR ", "a", "b", "c")

Upvotes: 1

dfa
dfa

Reputation: 116314

using Dollar should be simple:

String s1 = $(1, 3).join(" OR ");
String s2 = $(1, 4).join(" OR ");

where $(1, n) is a range object wrapper (there are wrappers for Collections, arrays, CharSequences, etc).

Upvotes: 1

Thomas Jung
Thomas Jung

Reputation: 33092

Unless, I'm missing something this is plain old join. Until Java 7 gets String.join (no joke) there are some implementations around like Apache commons lang StringUtils.join.

StringUtils.join(new Integer[] { 1, 2, 3, 4 }, "OR");

The only problem is that is does not work on primtive int[] arrays directly.

Upvotes: 6

Will
Will

Reputation: 5537

I think the simplest solution is writing a quick function that runs through the arguments in a for loop, appending “ OR ” + arg[i] to a StringBuilder, (with a special case for the first argument), then returning the StringBuilder's toString() value. How's this?

String format(String... args) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < args.length; i++) {
        if (i > 0) {
            sb.append(" OR ");
        }
        sb.append(args[i]);
    }
    return sb.toString();
}

Upvotes: 0

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