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<TITLE>Greedy and Nongreedy Matching in a Regular Expression
(Java Developers Almanac Example)
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<B><A HREF="../java.util.regex/pkg.html">java.util.regex</A></B><font color="#666666" SIZE="-2">
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<h3>
e427.
Greedy and Nongreedy Matching in a Regular Expression</h3>
By default, pattern matching is greedy, which means that the matcher
returns the longest match possible. For example, applying the pattern
<code>A.*c</code> to <code>AbcAbcA</code> matches <code>AbcAbc</code> rather than the shorter
<code>Abc</code>. To do nongreedy matching, a question mark must be added to
the quantifier. For example, the pattern <code>A.*?c</code> will find the
shortest match possible.
<pre>
// Greedy quantifiers
String match = find(<font color="#0066ff"><i>"A.*c"</i></font>, <font color="#0066ff"><i>"AbcAbc"</i></font>); // AbcAbc
match = find(<font color="#0066ff"><i>"A.+"</i></font>, <font color="#0066ff"><i>"AbcAbc"</i></font>); // AbcAbc
// Nongreedy quantifiers
match = find(<font color="#0066ff"><i>"A.*?c"</i></font>, <font color="#0066ff"><i>"AbcAbc"</i></font>); // Abc
match = find(<font color="#0066ff"><i>"A.+?"</i></font>, <font color="#0066ff"><i>"AbcAbc"</i></font>); // Abc
// Returns the first substring in input that matches the pattern.
// Returns null if no match found.
public static String find(String patternStr, CharSequence input) {
Pattern pattern = Pattern.compile(patternStr);
Matcher matcher = pattern.matcher(input);
if (matcher.find()) {
return matcher.group();
}
return null;
}
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Related Examples
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e423. <a class="eglink" href="BasicMatch.html?l=rel">
Quintessential Regular Expression Search Program
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e424. <a class="eglink" href="MatchExactly.html?l=rel">
Determining If a String Matches a Pattern Exactly
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e425. <a class="eglink" href="FromFile.html?l=rel">
Applying Regular Expressions on the Contents of a File
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e426. <a class="eglink" href="RemDupSpace.html?l=rel">
Removing Duplicate Whitespace in a String
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e428. <a class="eglink" href="Escape.html?l=rel">
Escaping Special Characters in a Pattern
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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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<a class="eglink" href="/egs/java.util.regex/pkg.html?l=rel#Tokenizing">
Tokenizing
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