diff --git a/runtime/syntax/java.vim b/runtime/syntax/java.vim
index 1b940eb..aec2955 100644
--- a/runtime/syntax/java.vim
+++ b/runtime/syntax/java.vim
@@ -2,7 +2,7 @@
 " Language:	Java
 " Maintainer:	Claudio Fleiner <claudio@fleiner.com>
 " URL:          https://github.com/fleiner/vim/blob/master/runtime/syntax/java.vim
-" Last Change:	2024 Feb 27
+" Last Change:	2024 Mar 01
 
 " Please check :help java.vim for comments on some of the options available.
 
@@ -226,20 +226,28 @@
 " Strings and constants
 syn match   javaSpecialError	 contained "\\."
 syn match   javaSpecialCharError contained "[^']"
-syn match   javaSpecialChar	 contained "\\\([4-9]\d\|[0-3]\d\d\|[\"\\'ntbrf]\|u\x\{4\}\)"
+" Escape Sequences (JLS-17, §3.10.7):
+syn match   javaSpecialChar	 contained "\\\%(u\x\x\x\x\|[0-3]\o\o\|\o\o\=\|[btnfr"'\\]\)"
 syn region  javaString		start=+"+ end=+"+ end=+$+ contains=javaSpecialChar,javaSpecialError,@Spell
-" next line disabled, it can cause a crash for a long line
+" The next line is commented out, it can cause a crash for a long line
 "syn match   javaStringError	  +"\([^"\\]\|\\.\)*$+
 syn match   javaCharacter	 "'[^']*'" contains=javaSpecialChar,javaSpecialCharError
 syn match   javaCharacter	 "'\\''" contains=javaSpecialChar
 syn match   javaCharacter	 "'[^\\]'"
-syn match   javaNumber		 "\<\(0[bB][0-1]\+\|0[0-7]*\|0[xX]\x\+\|\d\(\d\|_\d\)*\)[lL]\=\>"
-syn match   javaNumber		 "\(\<\d\(\d\|_\d\)*\.\(\d\(\d\|_\d\)*\)\=\|\.\d\(\d\|_\d\)*\)\([eE][-+]\=\d\(\d\|_\d\)*\)\=[fFdD]\="
-syn match   javaNumber		 "\<\d\(\d\|_\d\)*[eE][-+]\=\d\(\d\|_\d\)*[fFdD]\=\>"
-syn match   javaNumber		 "\<\d\(\d\|_\d\)*\([eE][-+]\=\d\(\d\|_\d\)*\)\=[fFdD]\>"
+" Integer literals (JLS-17, §3.10.1):
+syn keyword javaNumber		 0 0l 0L
+syn match   javaNumber		 "\<\%(0\%([xX]\x\%(_*\x\)*\|_*\o\%(_*\o\)*\|[bB][01]\%(_*[01]\)*\)\|[1-9]\%(_*\d\)*\)[lL]\=\>"
+" Decimal floating-point literals (JLS-17, §3.10.2):
+" Against "\<\d\+\>\.":
+syn match   javaNumber		 "\<\d\%(_*\d\)*\."
+syn match   javaNumber		 "\%(\<\d\%(_*\d\)*\.\%(\d\%(_*\d\)*\)\=\|\.\d\%(_*\d\)*\)\%([eE][-+]\=\d\%(_*\d\)*\)\=[fFdD]\=\>"
+syn match   javaNumber		 "\<\d\%(_*\d\)*[eE][-+]\=\d\%(_*\d\)*[fFdD]\=\>"
+syn match   javaNumber		 "\<\d\%(_*\d\)*\%([eE][-+]\=\d\%(_*\d\)*\)\=[fFdD]\>"
+" Hexadecimal floating-point literals (JLS-17, §3.10.2):
+syn match   javaNumber		 "\<0[xX]\%(\x\%(_*\x\)*\.\=\|\%(\x\%(_*\x\)*\)\=\.\x\%(_*\x\)*\)[pP][-+]\=\d\%(_*\d\)*[fFdD]\=\>"
 
-" unicode characters
-syn match   javaSpecial "\\u\d\{4\}"
+" Unicode characters
+syn match   javaSpecial "\\u\x\x\x\x"
 
 syn cluster javaTop add=javaString,javaCharacter,javaNumber,javaSpecial,javaStringError
 
@@ -265,16 +273,19 @@
 if exists("java_highlight_debug")
 
   " Strings and constants
-  syn match   javaDebugSpecial		contained "\\\d\d\d\|\\."
+  syn match   javaDebugSpecial		contained "\\\%(u\x\x\x\x\|[0-3]\o\o\|\o\o\=\|[btnfr"'\\]\)"
   syn region  javaDebugString		contained start=+"+  end=+"+  contains=javaDebugSpecial
-  syn match   javaDebugStringError	+"\([^"\\]\|\\.\)*$+
+  syn match   javaDebugStringError	contained +"\%([^"\\]\|\\.\)*$+
   syn match   javaDebugCharacter	contained "'[^\\]'"
   syn match   javaDebugSpecialCharacter contained "'\\.'"
   syn match   javaDebugSpecialCharacter contained "'\\''"
-  syn match   javaDebugNumber		contained "\<\(0[0-7]*\|0[xX]\x\+\|\d\+\)[lL]\=\>"
-  syn match   javaDebugNumber		contained "\(\<\d\+\.\d*\|\.\d\+\)\([eE][-+]\=\d\+\)\=[fFdD]\="
-  syn match   javaDebugNumber		contained "\<\d\+[eE][-+]\=\d\+[fFdD]\=\>"
-  syn match   javaDebugNumber		contained "\<\d\+\([eE][-+]\=\d\+\)\=[fFdD]\>"
+  syn keyword javaDebugNumber		contained 0 0l 0L
+  syn match   javaNumber		contained "\<\d\%(_*\d\)*\."
+  syn match   javaDebugNumber		contained "\<\%(0\%([xX]\x\%(_*\x\)*\|_*\o\%(_*\o\)*\|[bB][01]\%(_*[01]\)*\)\|[1-9]\%(_*\d\)*\)[lL]\=\>"
+  syn match   javaDebugNumber		contained "\%(\<\d\%(_*\d\)*\.\%(\d\%(_*\d\)*\)\=\|\.\d\%(_*\d\)*\)\%([eE][-+]\=\d\%(_*\d\)*\)\=[fFdD]\=\>"
+  syn match   javaDebugNumber		contained "\<\d\%(_*\d\)*[eE][-+]\=\d\%(_*\d\)*[fFdD]\=\>"
+  syn match   javaDebugNumber		contained "\<\d\%(_*\d\)*\%([eE][-+]\=\d\%(_*\d\)*\)\=[fFdD]\>"
+  syn match   javaDebugNumber		contained "\<0[xX]\%(\x\%(_*\x\)*\.\=\|\%(\x\%(_*\x\)*\)\=\.\x\%(_*\x\)*\)[pP][-+]\=\d\%(_*\d\)*[fFdD]\=\>"
   syn keyword javaDebugBoolean		contained true false
   syn keyword javaDebugType		contained null this super
   syn region javaDebugParen  start=+(+ end=+)+ contained contains=javaDebug.*,javaDebugParen