newbish question

Good evening,

Suppose, there is a file that has 1 line

Code:

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TAGS = 107,35,75,88

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Suppose there needs to be a task to read this line into a String[]
See my newbish Java and questions below (code works)

Code:

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private Properties inputFileProperties = new Properties();

String myTags = (String) inputFileProperties.get("TAGS");
String[] tags = new String[myTags.split(",").length];

int i = 0;
for (String x : myTags.split(",")) {
        tags[i] = x;
        i++;
}

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My question to you is:

1. Any way i can avoid "split"? I am mindful of that fact that split is expensive
2. Is there a better way to get a comma delimited string and push it into an array?

Assume:
1. I have no control over how many elements are comma delimited in the line
2. I don't have to do any data validation

Thank you very much for reading this and responding

PS: If you tell me how i can load it up from properties straight into a String array, it would be above awesome!

Quote:

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Originally Posted by mac

1. Any way i can avoid "split"? I am mindful of that fact that split is expensive
2. Is there a better way to get a comma delimited string and push it into an array?

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Do you believe that split is more expensive than reading the line from the file? Have you tested this in a profiler? This sounds a bit like premature optimization.

You could use indexOf and substring to split it yourself.

Thank you. I figured substring is better, but, could you provide an example of how i can take a string and store comma delimited vales into a String []

For that matter, if i have something like this

TAGS = 1,2,3,4,5,6

How can i tell how many elements this string has using substring, using "," as a delimiter?

PS:
Also, assume length of text between commas will vary.

Code:

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String input = "af,agy,3,d,hi,6";
ArrayList<String> stringAL = new ArrayList<String>();
while (true) {
    int index = input.indexOf(',');
    if (index == -1) // char not found
        index = input.length();
       
    String first = input.substring(0,index);
    stringAL.add(first);
    if (index != input.length())
        input = input.substring(index+1);
    else
        break;
}
String[] stringArray = stringAL.toArray(new String[stringAL.size()]);

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Didn't test, but should work.

Instead of cutting the input string into pieces, you could also use indexOf(int fromIndex, int char) instead of indexOf(int char).

I would definitely use substring() to get rid of the "TAGS = " part, but after that, why would you not want to use split()? It seems to me that split() does precisely what you want here, but you are making it much more complicated than it needs to be with this:

Code:

---

String[] tags = new String[myTags.split(",").length];

int i = 0;
for (String x : myTags.split(",")) {
        tags[i] = x;
        i++;
}

---

What is wrong with this?

Code:

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String[] tags = myTags.split(",");

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-Gary-

Forget the part about using substring() to get rid of "TAGS = " -- it looks like the Properties.get() method does that for you already.

-Gary-