parseline.html
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<TITLE>Parsing Character-Separated Data with a Regular Expression
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<B><A HREF="../java.util.regex/pkg.html">java.util.regex</A></B><font color="#666666" SIZE="-2">
[26 examples]
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<B><A HREF="../java.util.regex/pkg.html#Tokenizing">Tokenizing</A></B><font color="#666666" SIZE="-2">
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<h3>
e431.
Parsing Character-Separated Data with a Regular Expression</h3>
A line from a flat-file is typically formatted using a separator
character to separate the fields. If the separator is simply a comma,
tab, or single character, the <code>StringTokenizer</code> class can be used to
parse the line into fields. If the separator is more complex (e.g., a
space after a comma), a regular expression is needed.
<code>String.split()</code> conveniently parses a line using a regular
expression to specify the separator.
<P> <code>String.split()</code> returns only the nondelimiter strings. To
obtain the delimiter strings, see <a href="../java.util.regex/Tokenize.html" class="eglink"><font size="-1"><b>e432</b> Parsing a String into Tokens Using a Regular Expression</font></a>.
<P> Note: The <code>StringTokenizer</code> does not conveniently handle
empty fields properly. For example, given the line <code>a,,b</code>, rather
than return three fields (the second being empty), the
<code>StringTokenizer</code> returns two fields, discarding the empty field.
<code>String.split()</code> properly handles empty fields.
<pre>
// Parse a comma-separated string
String inputStr = <font color="#0066ff"><i>"a,,b"</i></font>;
String patternStr = <font color="#0066ff"><i>","</i></font>;
String[] fields = inputStr.split(patternStr);
// ["a", "", "b"]
// Parse a line whose separator is a comma followed by a space
inputStr = <font color="#0066ff"><i>"a, b, c,d"</i></font>;
patternStr = <font color="#0066ff"><i>", "</i></font>;
fields = inputStr.split(patternStr, -1);
// ["a", "b", "c,d"]
// Parse a line with and's and or's
inputStr = <font color="#0066ff"><i>"a, b, and c"</i></font>;
patternStr = <font color="#0066ff"><i>"[, ]+(and|or)*[, ]*"</i></font>;
fields = inputStr.split(patternStr, -1);
// ["a", "b", "c"]
</pre>
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Related Examples
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e432. <a class="eglink" href="Tokenize.html?l=rel">
Parsing a String into Tokens Using a Regular Expression
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See also:
<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Flags">
Flags
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<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Groups">
Groups
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<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Lines">
Lines
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<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Paragraphs">
Paragraphs
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<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Searching%20and%20Replacing">
Searching and Replacing
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