Better Java Detection

[qzind]

The A_slightly_better_Java_Launcher example in the Wiki fails to detect a 32-bit Java run-time on a 64-bit machine, which is common considering the amount of users which historically installed 32-bit Java for Chrome/Firefox.

The codeblock should help discover the 32-bit version (requires x64.nsh). This can go immediately before StrCpy $R0 "javaw.exe"

code:
  ; Fall-back to 32-bit registry

  ${If} ${RunningX64}

  ClearErrors

  ReadRegStr $R1 HKLM "Software\Wow6432Node\JavaSoft\Java Runtime Environment" "CurrentVersion"

  ReadRegStr $R0 HKLM "Software\Wow6432Node\JavaSoft\Java Runtime Environment\$R1" "JavaHome"

  StrCpy $R0 "$R0\bin\javaw.exe"

  IfErrors 0 JreFound

  ${EndIf}

  

However, due to the redirecting of ProgramFiles to ProgramFiles(x86) this still will have problem if the NSIS installer is in 32-bit mode, so some additional 64-bit detection logic is still required. The full source can be viewed here.

I haven't converted this example for generic usage yet, but it should be trivial to remove the variables our code is using and replace them with your own.