Java 中的 Matcher start(int)方法，示例
原文:https://www . geesforgeks . org/matcher-startint-method-in-Java-with-examples/
匹配器类的开始(int group) 方法用于从指定的组中获取已经完成的匹配结果的开始索引。
语法:
public int start(int group)
参数:该方法取一个参数组，该组是需要匹配模式的起始索引的组。
返回值:该方法返回指定组中第一个匹配字符的索引。
异常:此方法抛出:
- 如果尚未尝试匹配，或者如果先前的匹配操作失败，则illegalstatexception。
- 如果给定索引的模式中没有捕获组，则indexout of BoundSexception。
下面的例子说明了 Matcher.start()方法:
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*s)";
// Create a pattern from regex
Pattern pattern
= Pattern.compile(regex);
// Get the String to be matched
String stringToBeMatched
= "GeeksForGeeks";
// 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(1));
}
}
}
Output:
current Matcher:Java . util . regex . Matcher[pattern =(G * s)region = 0，13 lastmatch=] 4 12
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
= "GFGFGFGFGFGFGFGFGFG";
// 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(0));
}
}
}
Output:
当前匹配器:Java . util . regex . Matcher[pattern =(G * G)region = 0，19 last match =] 0 2 4 6 8 10 12 14 16 18
参考: 甲骨文文档
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