具有匹配文本和特殊字符的 Java 正则表达式

Question

Hi I am new to java regex. I have the below string

String s = " "KBC_2022-12-20-2004_IDEAL333_MASTER333_2022-12-20-1804_SUCCESS";

I wanted to only Print "333" which is appended with MASTER. The output should be 333. Can someone help me writing the regex for this. Basically the code should print the value between "MASTER" and the next "_". here its 333 but the value might be of any number of character not limit to length 3.

Answer 1

You can use this regex: (?<=MASTER)[0-9]+(?=\_) .

We are looking for everything between MASTER and _ :

• lookbehind : everything that goes after MASTER : (?<=MASTER)
• lookahead : everything that goes before _ : (?=\_)

Try on regex101.com

Answer 2

You can do MASTER(\\d+)_

Pattern p = Pattern.compile("MASTER(\\d+)_");
Matcher m = p.matcher(" KBC_2022-12-20-2004_IDEAL333_MASTER333_2022-12-20-1804_SUCCESS");
if (m.find()) {
    System.out.println(m.group(1)); // 333
}
m = p.matcher(" KBC_2022-12-20-2004_IDEAL333_MASTER123_2022-12-20-1804_SUCCESS");
if (m.find()) {
    System.out.println(m.group(1)); // 123
}