1. Line Anchors
In regex, anchors are not used to match characters. Rather they match a position i.e. before, after, or between characters. To match start and end of line, we use following anchors:
- Caret (^) matches the position before the first character in the string.
- Dollar ($) matches the position right after the last character in the string.
2. Regex patterns to match start of line
| Description | Matching Pattern |
|---|---|
| Line starts with number | “^\\d” or “^[0-9]” |
| Line starts with character | “^[a-z]” or “^[A-Z]” |
| Line starts with character (case-insensitive) | ^[a-zA-Z] |
| Line starts with word | “^word” |
| Line starts with special character | “^[!@#\\$%\\^\\&*\\)\\(+=._-]” |
import java.util.regex.Pattern;
public class Main {
public static void main(String[] args)
{
System.out.println(Pattern.compile("^[0-9]").matcher("1stKnight").find());
System.out.println(Pattern.compile("^[a-zA-Z]").matcher("FirstKnight").find());
System.out.println(Pattern.compile("^First").matcher("FirstKnight").find());
System.out.println(Pattern.compile("^[!@#\\$%\\^\\&*\\)\\(+=._-]")
.matcher("*1stKnight").find());
}
}
Program output.
true true true true
3. Regex patterns to match end of line
| Description | Matching Pattern |
|---|---|
| Line ends with number | “\\d$” or “[0-9]$” |
| Line ends with character | “[a-z]$” or “[A-Z]$” |
| Line ends with character (case-insensitive) | [a-zA-Z]$ |
| Line ends with word | “word$” |
| Line ends with special character | “[!@#\\$%\\^\\&*\\)\\(+=._-]$” |
public class Main {
public static void main(String[] args)
{
System.out.println(Pattern.compile("[0-9]$").matcher("FirstKnight123").find());
System.out.println(Pattern.compile("[a-zA-Z]$").matcher("FirstKnight").find());
System.out.println(Pattern.compile("Knight$").matcher("FirstKnight").find());
System.out.println(Pattern.compile("[!@#\\$%\\^\\&*\\)\\(+=._-]$")
.matcher("FirstKnight&").find());
}
}
Program output.
true true true true
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