即使存在匹配项，Matcher.find()也会返回 false
我的代码：
String next_line = " I MQ (AELTPHQXRU) (BKNW) (CMOY) (DFG) (IV) (JZ) (S)"
String regex_cycle = "\\([\\s()a-zA-Z]+\\)"; #matches "(AELTPHQXRU) (BKNW) (CMOY) (DFG) (IV) (JZ) (S)"
String regex_rotorName = "^[^\\s()RNM]+"; #matches "I"
String regex_rotorDescriptor = "^[MNR][^\\s()]*"; #matches "MQ"
Matcher name_matcher = Pattern.compile(regex_rotorName).matcher(next_line);
Matcher cycle_matcher = Pattern.compile(regex_cycle).matcher(next_line);
Matcher descriptor_matcher = Pattern.compile(regex_rotorDescriptor).matcher(next_line);
System.out.println(name_matcher.find());
System.out.println(cycle_matcher.find());
System.out.println(descriptor_matcher.find());
出于某种原因，我的matcher.find()返回 false。
如图所示，next_line 等于“I MQ (AELTPHQXRU) (BKNW) (CMOY) (DFG) (IV) (JZ) (S)。”。
所有三个 find() 都应该根据这个字符串返回 true，对吗？
String next_line = " I MQ (AELTPHQXRU) (BKNW) (CMOY) (DFG) (IV) (JZ) (S)"
String regex_cycle = "\\([\\s()a-zA-Z]+\\)"; #matches "(AELTPHQXRU) (BKNW) (CMOY) (DFG) (IV) (JZ) (S)"
String regex_rotorName = "^[^\\s()RNM]+"; #matches "I"
String regex_rotorDescriptor = "^[MNR][^\\s()]*"; #matches "MQ"
Matcher name_matcher = Pattern.compile(regex_rotorName).matcher(next_line);
Matcher cycle_matcher = Pattern.compile(regex_cycle).matcher(next_line);
Matcher descriptor_matcher = Pattern.compile(regex_rotorDescriptor).matcher(next_line);
System.out.println(name_matcher.find());
System.out.println(cycle_matcher.find());
System.out.println(descriptor_matcher.find());
For some reason, my matcher.find()'s are returning false.
As seen in the image, next_line equals " I MQ (AELTPHQXRU) (BKNW) (CMOY) (DFG) (IV) (JZ) (S).".
All three find()s should return true based on this string right?
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您似乎在 System.out 语句中的
if之前调用find()，以便它们报告第二个匹配项，而不是第一个匹配项。分配给局部变量并使用 System.out.println 和 if 中的值
You appear to be calling
find()in System.out statements immediately before theifso that they are reporting the second matches, not first match.Assign to local variable and use the values in
System.out.printlnandif