I am trying to build up a installer for my software by Inno Setup.
But a weird thing happened：
I try to run the Pascal code to get the Java version in Inno Setup script
Exec('cmd.exe', '/c java -version 2> ' + tempDirPath+jdkVersionInfoFile, '',
SW_HIDE, ewWaitUntilTerminated, ResultCode)
The result is java verison "1.6".
And when I typed the command java -version in console window, then I get the result is java version "1.8".
Why are the results different?
While I cannot imagine how exactly this happens on your machine without more details, differences like this typically stem from the fact that Inno Setup is 32-bit application.
It's likely that 32-bit version of Java is run by Inno Setup (32-bit application) and 64-bit version of Java is run by Windows command interpreter (64-bit application). And you have different versions installed for these platforms.
(Assuming that you run 64-bit version of Windows).
See Install Mode: 32-bit vs. 64-bit article in Inno Setup documentation.