Recuperar o conteúdo do uma tag HTML com regex

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Regex
<tag.*<\/tag>
ou
<tag>(?:[^\n]*(\n+|.*))+</tag>
ou

<\s*tag[^>]*>(.*?)<\s*/\s*tag>

ou

(?<=<\s*tag[^>]*>)(.*?)(?=<\s*/\s*tag\s*>)

ou
(?<=<root.*>\n*)(.*?)(?=\n*</root>)

ou
(?<=<tag.*>\n*)(.*?)(?=\n*</tag>)

String de teste

<root>

<tag id=rodrigo para seual >valor</tag>

</root>

<root>

<tag id="meu id">valor</tag>

</root>

<root><tag id="meu id">valor</tag></root>

(?<=% of )(.*)(?= at )

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regex no java


String html="<root><tag>Medicamento</tag></root>"
String conteudo = null;
Pattern pattern = Pattern.compile("<tag.*<\\/tag>");
Matcher matcher = pattern.matcher(html);
if (matcher.find()) {
    conteudo = matcher.group(0).replace("<tag>", "").replace("</tag>", "").toUpperCase();
}