source: node_modules/highlight.js/lib/languages/java.js

// https://docs.oracle.com/javase/specs/jls/se15/html/jls-3.html#jls-3.10
var decimalDigits = '[0-9](_*[0-9])*';
var frac = `\\.(${decimalDigits})`;
var hexDigits = '[0-9a-fA-F](_*[0-9a-fA-F])*';
var NUMERIC = {
  className: 'number',
  variants: [
    // DecimalFloatingPointLiteral
    // including ExponentPart
    { begin: `(\\b(${decimalDigits})((${frac})|\\.)?|(${frac}))` +
      `[eE][+-]?(${decimalDigits})[fFdD]?\\b` },
    // excluding ExponentPart
    { begin: `\\b(${decimalDigits})((${frac})[fFdD]?\\b|\\.([fFdD]\\b)?)` },
    { begin: `(${frac})[fFdD]?\\b` },
    { begin: `\\b(${decimalDigits})[fFdD]\\b` },

    // HexadecimalFloatingPointLiteral
    { begin: `\\b0[xX]((${hexDigits})\\.?|(${hexDigits})?\\.(${hexDigits}))` +
      `[pP][+-]?(${decimalDigits})[fFdD]?\\b` },

    // DecimalIntegerLiteral
    { begin: '\\b(0|[1-9](_*[0-9])*)[lL]?\\b' },

    // HexIntegerLiteral
    { begin: `\\b0[xX](${hexDigits})[lL]?\\b` },

    // OctalIntegerLiteral
    { begin: '\\b0(_*[0-7])*[lL]?\\b' },

    // BinaryIntegerLiteral
    { begin: '\\b0[bB][01](_*[01])*[lL]?\\b' },
  ],
  relevance: 0
};

/*
Language: Java
Author: Vsevolod Solovyov <vsevolod.solovyov@gmail.com>
Category: common, enterprise
Website: https://www.java.com/
*/

function java(hljs) {
  var JAVA_IDENT_RE = '[\u00C0-\u02B8a-zA-Z_$][\u00C0-\u02B8a-zA-Z_$0-9]*';
  var GENERIC_IDENT_RE = JAVA_IDENT_RE + '(<' + JAVA_IDENT_RE + '(\\s*,\\s*' + JAVA_IDENT_RE + ')*>)?';
  var KEYWORDS = 'false synchronized int abstract float private char boolean var static null if const ' +
    'for true while long strictfp finally protected import native final void ' +
    'enum else break transient catch instanceof byte super volatile case assert short ' +
    'package default double public try this switch continue throws protected public private ' +
    'module requires exports do';

  var ANNOTATION = {
    className: 'meta',
    begin: '@' + JAVA_IDENT_RE,
    contains: [
      {
        begin: /\(/,
        end: /\)/,
        contains: ["self"] // allow nested () inside our annotation
      },
    ]
  };
  const NUMBER = NUMERIC;

  return {
    name: 'Java',
    aliases: ['jsp'],
    keywords: KEYWORDS,
    illegal: /<\/|#/,
    contains: [
      hljs.COMMENT(
        '/\\*\\*',
        '\\*/',
        {
          relevance: 0,
          contains: [
            {
              // eat up @'s in emails to prevent them to be recognized as doctags
              begin: /\w+@/, relevance: 0
            },
            {
              className: 'doctag',
              begin: '@[A-Za-z]+'
            }
          ]
        }
      ),
      // relevance boost
      {
        begin: /import java\.[a-z]+\./,
        keywords: "import",
        relevance: 2
      },
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      hljs.APOS_STRING_MODE,
      hljs.QUOTE_STRING_MODE,
      {
        className: 'class',
        beginKeywords: 'class interface enum', end: /[{;=]/, excludeEnd: true,
        // TODO: can this be removed somehow?
        // an extra boost because Java is more popular than other languages with
        // this same syntax feature (this is just to preserve our tests passing
        // for now)
        relevance: 1,
        keywords: 'class interface enum',
        illegal: /[:"\[\]]/,
        contains: [
          { beginKeywords: 'extends implements' },
          hljs.UNDERSCORE_TITLE_MODE
        ]
      },
      {
        // Expression keywords prevent 'keyword Name(...)' from being
        // recognized as a function definition
        beginKeywords: 'new throw return else',
        relevance: 0
      },
      {
        className: 'class',
        begin: 'record\\s+' + hljs.UNDERSCORE_IDENT_RE + '\\s*\\(',
        returnBegin: true,
        excludeEnd: true,
        end: /[{;=]/,
        keywords: KEYWORDS,
        contains: [
          { beginKeywords: "record" },
          {
            begin: hljs.UNDERSCORE_IDENT_RE + '\\s*\\(',
            returnBegin: true,
            relevance: 0,
            contains: [hljs.UNDERSCORE_TITLE_MODE]
          },
          {
            className: 'params',
            begin: /\(/, end: /\)/,
            keywords: KEYWORDS,
            relevance: 0,
            contains: [
              hljs.C_BLOCK_COMMENT_MODE
            ]
          },
          hljs.C_LINE_COMMENT_MODE,
          hljs.C_BLOCK_COMMENT_MODE
        ]
      },
      {
        className: 'function',
        begin: '(' + GENERIC_IDENT_RE + '\\s+)+' + hljs.UNDERSCORE_IDENT_RE + '\\s*\\(', returnBegin: true, end: /[{;=]/,
        excludeEnd: true,
        keywords: KEYWORDS,
        contains: [
          {
            begin: hljs.UNDERSCORE_IDENT_RE + '\\s*\\(', returnBegin: true,
            relevance: 0,
            contains: [hljs.UNDERSCORE_TITLE_MODE]
          },
          {
            className: 'params',
            begin: /\(/, end: /\)/,
            keywords: KEYWORDS,
            relevance: 0,
            contains: [
              ANNOTATION,
              hljs.APOS_STRING_MODE,
              hljs.QUOTE_STRING_MODE,
              NUMBER,
              hljs.C_BLOCK_COMMENT_MODE
            ]
          },
          hljs.C_LINE_COMMENT_MODE,
          hljs.C_BLOCK_COMMENT_MODE
        ]
      },
      NUMBER,
      ANNOTATION
    ]
  };
}

module.exports = java;