java - java中句子中前三个字母的正则表达式

Question

如何在java中为下面类似的句子编写正则表达式，并且只匹配句子的前三个字符

ins(clear(icl>remove>do,plf>thing,obj>thing,ins>thing).@entry.@past,evidence(icl>indication>thing))

我尝试了这段代码，但它也与句子中清晰的证据相匹配......

String pattern2="[-a-z0-9R:._-`&=*'`~\"\\+[\\s]]+[\\(]";  

Pattern r2 = Pattern.compile(pattern2);
Matcher m2 = r2.matcher(line);


 while (m2.find()) 
 {
     rel = m2.group();
     rel = rel.substring(0, rel.length()-1).trim();                 
     System.out.println("The relation are " + rel); 
 }

Answer 1

我想你应该首先删除所有非字母

String result = string.replaceAll("[^a-zA-Z]", "");

然后只取前三个符号:

result.substring(0, 3)