带有单词和数字的 Java 字符串模式

Question

I have some problems with the pattern in Java. I followed all of the steps in Regex but these lines of code are not working!

Pattern p = Pattern.compile("[a-zA-Z]{4}-[0-9]{1}");
        if (p.matcher(id).matches())
        this.id = id;
        else
        System.out.println("Wrong format!");

Whenever I type ABCD-0123, it is false and prints out wrong format

Answer 1

[0-9]{1} means only one digit (in the end of you pattern), and you are invoking matches , which considers the whole input.

Either adjust the digits to {4} or whatever you need, or invoke find instead of matches .

The latter ( find ) will... find the pattern inside your given input, instead of matching against the whole input.

Useful for patterns describing part of the input.

Answer 2

Replace the regex condition by [a-zA-Z]{4}-[0-9]+

• [a-zA-Z]{4}: contains letters of the alphabet and must be exactly 4 letters.
• Followed by a "-"
• Then digits [0-9]+(if you want to set the size of the replace the + by {n} n is equal to the number of digits