diff --git a/runtime/autoload/spotbugs.vim b/runtime/autoload/spotbugs.vim
new file mode 100644
index 0000000..9161395
--- /dev/null
+++ b/runtime/autoload/spotbugs.vim
@@ -0,0 +1,250 @@
+" Default pre- and post-compiler actions for SpotBugs
+" Maintainers:  @konfekt and @zzzyxwvut
+" Last Change:  2024 Nov 27
+
+let s:save_cpo = &cpo
+set cpo&vim
+
+if v:version > 900
+
+  function! spotbugs#DeleteClassFiles() abort
+    if !exists('b:spotbugs_class_files')
+      return
+    endif
+
+    for pathname in b:spotbugs_class_files
+      let classname = pathname =~# "^'.\\+\\.class'$"
+          \ ? eval(pathname)
+          \ : pathname
+
+      if classname =~# '\.class$' && filereadable(classname)
+        " Since v9.0.0795.
+        let octad = readblob(classname, 0, 8)
+
+        " Test the magic number and the major version number (45 for v1.0).
+        " Since v9.0.2027.
+        if len(octad) == 8 && octad[0 : 3] == 0zcafe.babe &&
+              \ or((octad[6] << 8), octad[7]) >= 45
+          echomsg printf('Deleting %s: %d', classname, delete(classname))
+        endif
+      endif
+    endfor
+
+    let b:spotbugs_class_files = []
+  endfunction
+
+else
+
+  function! s:DeleteClassFilesWithNewLineCodes(classname) abort
+    " The distribution of "0a"s in class file versions 2560 and 2570:
+    "
+    " 0zca.fe.ba.be.00.00.0a.00    0zca.fe.ba.be.00.00.0a.0a
+    " 0zca.fe.ba.be.00.0a.0a.00    0zca.fe.ba.be.00.0a.0a.0a
+    " 0zca.fe.ba.be.0a.00.0a.00    0zca.fe.ba.be.0a.00.0a.0a
+    " 0zca.fe.ba.be.0a.0a.0a.00    0zca.fe.ba.be.0a.0a.0a.0a
+    let numbers = [0, 0, 0, 0, 0, 0, 0, 0]
+    let offset = 0
+    let lines = readfile(a:classname, 'b', 4)
+
+    " Track NL byte counts to handle files of less than 8 bytes.
+    let nl_cnt = len(lines)
+    " Track non-NL byte counts for "0zca.fe.ba.be.0a.0a.0a.0a".
+    let non_nl_cnt = 0
+
+    for line in lines
+      for idx in range(strlen(line))
+        " Remap NLs to Nuls.
+        let numbers[offset] = (line[idx] == "\n") ? 0 : char2nr(line[idx]) % 256
+        let non_nl_cnt += 1
+        let offset += 1
+
+        if offset > 7
+          break
+        endif
+      endfor
+
+      let nl_cnt -= 1
+
+      if offset > 7 || (nl_cnt < 1 && non_nl_cnt > 4)
+        break
+      endif
+
+      " Reclaim NLs.
+      let numbers[offset] = 10
+      let offset += 1
+
+      if offset > 7
+        break
+      endif
+    endfor
+
+    " Test the magic number and the major version number (45 for v1.0).
+    if offset > 7 && numbers[0] == 0xca && numbers[1] == 0xfe &&
+          \ numbers[2] == 0xba && numbers[3] == 0xbe &&
+          \ (numbers[6] * 256 + numbers[7]) >= 45
+      echomsg printf('Deleting %s: %d', a:classname, delete(a:classname))
+    endif
+  endfunction
+
+  function! spotbugs#DeleteClassFiles() abort
+    if !exists('b:spotbugs_class_files')
+      return
+    endif
+
+    let encoding = &encoding
+
+    try
+      set encoding=latin1
+
+      for pathname in b:spotbugs_class_files
+        let classname = pathname =~# "^'.\\+\\.class'$"
+            \ ? eval(pathname)
+            \ : pathname
+
+        if classname =~# '\.class$' && filereadable(classname)
+          let line = get(readfile(classname, 'b', 1), 0, '')
+          let length = strlen(line)
+
+          " Test the magic number and the major version number (45 for v1.0).
+          if length > 3 && line[0 : 3] == "\xca\xfe\xba\xbe"
+            if length > 7 && ((line[6] == "\n" ? 0 : char2nr(line[6]) % 256) * 256 +
+                    \ (line[7] == "\n" ? 0 : char2nr(line[7]) % 256)) >= 45
+              echomsg printf('Deleting %s: %d', classname, delete(classname))
+            else
+              call s:DeleteClassFilesWithNewLineCodes(classname)
+            endif
+          endif
+        endif
+      endfor
+    finally
+      let &encoding = encoding
+    endtry
+
+    let b:spotbugs_class_files = []
+  endfunction
+
+endif
+
+function! spotbugs#DefaultPostCompilerAction() abort
+  " Since v7.4.191.
+  make %:S
+endfunction
+
+" Look for "spotbugs#compiler" in "ftplugin/java.vim".
+let s:compiler = exists('spotbugs#compiler') ? spotbugs#compiler : ''
+let s:readable = filereadable($VIMRUNTIME . '/compiler/' . s:compiler . '.vim')
+
+if s:readable && s:compiler ==# 'maven' && executable('mvn')
+
+  function! spotbugs#DefaultPreCompilerAction() abort
+    call spotbugs#DeleteClassFiles()
+    compiler maven
+    make compile
+  endfunction
+
+  function! spotbugs#DefaultPreCompilerTestAction() abort
+    call spotbugs#DeleteClassFiles()
+    compiler maven
+    make test-compile
+  endfunction
+
+  function! spotbugs#DefaultProperties() abort
+    return {
+        \ 'PreCompilerAction':
+            \ function('spotbugs#DefaultPreCompilerAction'),
+        \ 'PreCompilerTestAction':
+            \ function('spotbugs#DefaultPreCompilerTestAction'),
+        \ 'PostCompilerAction':
+            \ function('spotbugs#DefaultPostCompilerAction'),
+        \ 'sourceDirPath':      'src/main/java',
+        \ 'classDirPath':       'target/classes',
+        \ 'testSourceDirPath':  'src/test/java',
+        \ 'testClassDirPath':   'target/test-classes',
+        \ }
+  endfunction
+
+  unlet s:readable s:compiler
+elseif s:readable && s:compiler ==# 'ant' && executable('ant')
+
+  function! spotbugs#DefaultPreCompilerAction() abort
+    call spotbugs#DeleteClassFiles()
+    compiler ant
+    make compile
+  endfunction
+
+  function! spotbugs#DefaultPreCompilerTestAction() abort
+    call spotbugs#DeleteClassFiles()
+    compiler ant
+    make compile-test
+  endfunction
+
+  function! spotbugs#DefaultProperties() abort
+    return {
+        \ 'PreCompilerAction':
+            \ function('spotbugs#DefaultPreCompilerAction'),
+        \ 'PreCompilerTestAction':
+            \ function('spotbugs#DefaultPreCompilerTestAction'),
+        \ 'PostCompilerAction':
+            \ function('spotbugs#DefaultPostCompilerAction'),
+        \ 'sourceDirPath':      'src',
+        \ 'classDirPath':       'build/classes',
+        \ 'testSourceDirPath':  'test',
+        \ 'testClassDirPath':   'build/test/classes',
+        \ }
+  endfunction
+
+  unlet s:readable s:compiler
+elseif s:readable && s:compiler ==# 'javac' && executable('javac')
+
+  function! spotbugs#DefaultPreCompilerAction() abort
+    call spotbugs#DeleteClassFiles()
+    compiler javac
+
+    if get(b:, 'javac_makeprg_params', get(g:, 'javac_makeprg_params', '')) =~ '\s@\S'
+      " Read options and filenames from @options [@sources ...].
+      make
+    else
+      " Let Javac figure out what files to compile.
+      execute 'make ' . join(map(filter(copy(v:argv),
+          \ "v:val =~# '\\.java\\=$'"),
+          \ 'shellescape(v:val)'), ' ')
+    endif
+  endfunction
+
+  function! spotbugs#DefaultPreCompilerTestAction() abort
+    call spotbugs#DefaultPreCompilerAction()
+  endfunction
+
+  function! spotbugs#DefaultProperties() abort
+    return {
+        \ 'PreCompilerAction':
+            \ function('spotbugs#DefaultPreCompilerAction'),
+        \ 'PreCompilerTestAction':
+            \ function('spotbugs#DefaultPreCompilerTestAction'),
+        \ 'PostCompilerAction':
+            \ function('spotbugs#DefaultPostCompilerAction'),
+        \ }
+  endfunction
+
+  unlet s:readable s:compiler
+else
+
+  function! spotbugs#DefaultPreCompilerAction() abort
+    echomsg printf('Not supported: "%s"', s:compiler)
+  endfunction
+
+  function! spotbugs#DefaultPreCompilerTestAction() abort
+    call spotbugs#DefaultPreCompilerAction()
+  endfunction
+
+  function! spotbugs#DefaultProperties() abort
+    return {}
+  endfunction
+
+  unlet s:readable
+endif
+
+let &cpo = s:save_cpo
+unlet s:save_cpo
+
+" vim: set foldmethod=syntax shiftwidth=2 expandtab: