How to get Java Version from batch script?

I am trying to get '6' out of the java version output given below

java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b07)
Java HotSpot(TM) Client VM (build 17.0-b17, mixed mode, sharing)

For the same I wrote this batch script

set VERSION6="1.6.0_21"
java -version 2>&1 | findstr "version" >ab.txt
for /f 开发者_运维知识库"tokens=3" %%g in (ab.txt) do (
  if not %%g == %VERSION6% echo %%g
  echo %%g
)

%%g displays "1.6.0_21"

May someone guide me to correct direction? I am not much familiar with for /f.

---

@echo off
setlocal

set VERSION6="1.6.0_21"
for /f "tokens=3" %%g in ('java -version 2^>^&1 ^| findstr /i "version"') do (
    @echo Output: %%g
    set JAVAVER=%%g
)
set JAVAVER=%JAVAVER:"=%
@echo Output: %JAVAVER%

for /f "delims=. tokens=1-3" %%v in ("%JAVAVER%") do (
    @echo Major: %%v
    @echo Minor: %%w
    @echo Build: %%x
)

endlocal

In the first for loop, "tokens=3" says that we're going to just use the third token from the command output. Rather than redirect the output of the java -version command to a file, we can run this command within the for loop itself. The carets (^) are escape characters, and are needed so we can embed the >, & and | symbols in the command string.

Within the body of the for loop, we set a new var, JAVAVER, so that we can do some manipulation of the version string later.

The set JAVAVER=%JAVAVER:"=% command removes the double quotes from around the version string.

The last for loop parses the java version string. delims=. says we're going to delimit tokens using periods. tokens=1-3 says we're going to pass the first three tokens from the string to the body of the loop. We can now get the components of the java version string using the explicit variable, %%v and the implied variables (next letters in the alphabet) %%w and %%x.

When I run this on my system I get:

Output: "1.6.0_24" 
Output: 1.6.0_24
Major: 1 
Minor: 6 
Build: 0_24

---

I've made some modification to Patrick's answer so it works with Java 9, 10, etc. This returns minor version for 1.x, and major version for Java 9, 10, etc.

@echo off
setlocal

rem We use the value the JAVACMD environment variable, if defined
rem and then try JAVA_HOME
set "_JAVACMD=%JAVACMD%"
if "%_JAVACMD"=="" (
  if not "%JAVA_HOME%"=="" (
    if exist "%JAVA_HOME%\bin\java.exe" set "_JAVACMD=%JAVA_HOME%\bin\java.exe"
  )
)
if "%_JAVACMD%"=="" set _JAVACMD=java

rem Parses x out of 1.x; for example 8 out of java version 1.8.0_xx
rem Otherwise, parses the major version; 9 out of java version 9-ea
set JAVA_VERSION=0
for /f "tokens=3" %%g in ('%_JAVACMD% -Xms32M -Xmx32M -version 2^>^&1 ^| findstr /i "version"') do (
  set JAVA_VERSION=%%g
)
set JAVA_VERSION=%JAVA_VERSION:"=%
for /f "delims=.-_ tokens=1-2" %%v in ("%JAVA_VERSION%") do (
  if /I "%%v" EQU "1" (
    set JAVA_VERSION=%%w
  ) else (
    set JAVA_VERSION=%%v
  )
)

@echo %JAVA_VERSION%

endlocal

echoes 8 or 17 etc.

---

This will extract the minor part of the version number:

java -version 2>&1 | awk '/version/ {print $3}' | awk -F . '{print $2}'

However, it may be better to extract the major.minor and match on that in case Oracle ever change the version number scheme again e.g.:

java -version 2>&1 | awk '/version/ {print $3}' | egrep -o '[0-9]+\.[0-9]+'

---

for /f tokens^=2-5^ delims^=.-_+^" %j in ('java -fullversion 2^>^&1') do @set "jver=%j%k%l%m"

This will store the java version into jver variable and as integer And you can use it for comparisons .E.G

if %jver% LSS 16000 echo not supported version

.You can use more major version by removing %k and %l and %m.This command prompt version.

For .bat use this:

@echo off
PATH %PATH%;%JAVA_HOME%\bin\
for /f tokens^=2-5^ delims^=.-_+^" %%j in ('java -fullversion 2^>^&1') do set "jver=%%j%%k%%l%%m"

According to my tests this is the fastest way to get the java version from bat (as it uses only internal commands and not external ones as FIND,FINDSTR and does not use GOTO which also can slow the script). Some JDK vendors does not support -fullversion switch or their implementation is not the same as this one provided by Oracle (better avoid them).