I need something simmilar to "awk { print $1 }", but for java. I have a string, similar to this:
word1 word2 word3 word4 word5 word6
How, can I substring first word, from every line?
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3 Answers
String example = "word1 word2 word3 word4 word5 word6";
String firstWord = example.split(" ", 2)[0];
4 Comments
Arthur Thomas
Just be sure that list isn't empty as you go through the data. :)
Mark Byers
Using split(" ", 1) would be better. It reduces the number of unnecessary strings created to only one unnecessary string instead of lots.
Mark Byers
Oops should be 2 sorry. "The limit parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array. If the limit n is greater than zero then the pattern will be applied at most n - 1 times" from java.sun.com/j2se/1.4.2/docs/api/java/lang/…
Mark Byers
I fixed it for you, seeing as it was my fault!
Here's a solution that doesn't fail if there is only one word on the line. I assume that you have already stripped the new line characters, and that space is the only allowed separator:
for (String line: lines)
{
int index = line.indexOf(' ');
String firstWord;
if (index >= 0)
{
firstWord = line.substring(0, index);
}
else
{
firstWord = line;
}
System.out.println(firstWord);
}
3 Comments
Valentin Rocher
my solution doesn't fail if there is only one word...if split() cannot find the separator, it just keeps the string in the first element of the array.
Mark Byers
My solution doesn't fail either. Plus it uses much less memory and it doesn't scan the entire string. You should at least add the optimization I suggested as a comment to your answer.
Valentin Rocher
done, thanks (I was just answering the "here is a solution that doesn't fail...")
String example = "word1 word2 word3 word4 word5 word6";
int indexOf = example.indexOf(" ");
String firstWord = example.substring(0, indexOf == -1? example.length: indexOf);
2 Comments
Mark Byers
This fails if the line only has one word.
lins314159
Now it'll give you an empty string if you've only got one word.