Matcher类的start()方法用于获取已经完成的匹配结果的起始索引。
用法:
public int start()
参数:此方法不带任何参数。
返回值:此方法返回匹配的第一个字符的索引。0
异常:如果尚未尝试匹配,或者先前的匹配操作失败,则此方法引发IllegalStateException。
下面的示例说明Matcher.start()方法:
示例1:
// Java code to illustrate start() method
import java.util.regex.*;
public class GFG {
public static void main(String[] args)
{
// Get the regex to be checked
String regex = "(G*k)";
// Create a pattern from regex
Pattern pattern
= Pattern.compile(regex);
// Get the String to be matched
String stringToBeMatched = "Geeks";
// Create a matcher for the input String
Matcher matcher
= pattern
.matcher(stringToBeMatched);
// Get the current matcher state
MatchResult result
= matcher.toMatchResult();
System.out.println("Current Matcher: "
+ result);
while (matcher.find()) {
// Get the first index of match result
System.out.println(matcher.start());
}
}
}
输出:
Current Matcher: java.util.regex.Matcher[pattern=(G*k) region=0,5 lastmatch=]
3
示例2:
// Java code to illustrate start() method
import java.util.regex.*;
public class GFG {
public static void main(String[] args)
{
// Get the regex to be checked
String regex = "(G*G)";
// Create a pattern from regex
Pattern pattern
= Pattern.compile(regex);
// Get the String to be matched
String stringToBeMatched = "GFG";
// Create a matcher for the input String
Matcher matcher
= pattern
.matcher(stringToBeMatched);
// Get the current matcher state
MatchResult result
= matcher.toMatchResult();
System.out.println("Current Matcher: "
+ result);
while (matcher.find()) {
// Get the first index of match result
System.out.println(matcher.start());
}
}
}
输出:
Current Matcher: java.util.regex.Matcher[pattern=(G*G) region=0,3 lastmatch=]
0
2
参考: Oracle Doc
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注:本文由纯净天空筛选整理自Kirti_Mangal大神的英文原创作品 Matcher start() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。