Text Processingflags: m

Java Package Declaration

Match Java `package com.example.app;` declarations and capture the dotted package path.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("^\\s*package\\s+([a-z][\\w]*(?:\\.[a-z][\\w]*)*)\\s*;", "m");
const input = "package com.example.app;";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

Python (re) code

pyPython

import re

pattern = re.compile(r"^\s*package\s+([a-z][\w]*(?:\.[a-z][\w]*)*)\s*;", re.MULTILINE)
input_text = "package com.example.app;"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`(?m)^\s*package\s+([a-z][\w]*(?:\.[a-z][\w]*)*)\s*;`)
	input := `package com.example.app;`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

^\s*package\s+([a-z][\w]*(?:\.[a-z][\w]*)*)\s*;   (flags: m)

Raw source: ^\s*package\s+([a-z][\w]*(?:\.[a-z][\w]*)*)\s*;

How it works

^\s* allows leading whitespace at line start (m flag enables per-line). package\s+ requires the keyword. ([a-z][\w]*(?:\.[a-z][\w]*)*) captures the package path: each segment must start with a lowercase letter (Java convention) and continue with word characters. \s*; matches the required terminating semicolon.