Java check latest version programmatically

Question

Goal: check java\'s version on a machine (I can get this from java -version). Compare it with latest available from java website

I woul

Answer 1

You could parse the Java SE Downloads page to extract the Java versions.
That way, you get the version of both JDK6 and JDK7, which allows you to test your particular JDK (6 or 7) against the latest Oracle one.
(As opposed to the Free Java Download page, which only lists the JDK7)

Her is a crude script in Go, which you can compile on Windows, Unix, MacOs into a single independent executable, and use within a command line or a script:

package main

import (
    "bytes"
    "encoding/xml"
    "fmt"
    "io/ioutil"
    "net/http"
    "os/exec"
    "regexp"
)

type Jdk struct {
    Url    string
    Ver    string
    update string
}

func main() {
    resp, err := http.Get("http://www.oracle.com/technetwork/java/javase/downloads/index.html")
    if err != nil {
        fmt.Printf("Error on http Get: %v\n", err)
        return
    }
    bodyb, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Printf("QueriesForOwner: error in ReadAll: %v\n", err)
        return
    }
    br := bytes.NewBuffer(bodyb)
    jdkre, err := regexp.Compile(`h3[^\r\n]+(/technetwork/java/javase/downloads/(jdk(?:6|7)(?:u(\d+))?)-downloads-\d+\.html)`)
    if err != nil {
        fmt.Printf("extract: error in regexp compilation: %v\n", err)
        return
    }
    jdks := jdkre.FindAllSubmatch(br.Bytes(), -1)
    jdk7 := Jdk{string(jdks[0][4]), string(jdks[0][5]), string(jdks[0][6])}
    jdk6 := Jdk{string(jdks[1][7]), string(jdks[1][8]), string(jdks[1][9])}
    fmt.Printf("Jdk7: %v\nJdk6: %v\n", jdk7, jdk6)
    jver, err := exec.Command("java", "-version").CombinedOutput()
    if err != nil {
        fmt.Printf("*ExitError from java -version:", err)
        return
    }
    fmt.Println("JVer: '", string(jver), "'")
    jverre, err := regexp.Compile(`1.(\d).\d(?:_(\d+))"`)
    jvers := jverre.FindSubmatch(jver)
    jj := string(jvers[0])
    jv := string(jvers[1])
    ju := string(jvers[2])
    jdk := jdk6
    if jv == "7" {
        jdk = jdk7
    }
    if jdk.update != ju {
        fmt.Println("Local JDK *NOT* up-to-date: you have ", jj, ", Oracle has ", jdk.Ver)
    } else {
        fmt.Println("Local JDK *up-to-date*: you have ", jj, ", equals to Oracle, which has", jdk.Ver)
    }
}

Again, this is a crude script, oriented toward JDK, and you would need to adapt it to your specific need, making its output and exit status match what you need for your script.

On my (PC) workstation, it returns:

Jdk7: {/technetwork/java/javase/downloads/jdk7u9-downloads-1859576.html jdk7u9 9}
Jdk6: {/technetwork/java/javase/downloads/jdk6u37-downloads-1859587.html jdk6u37 37}
JVer: ' java version "1.6.0_31"
Java(TM) SE Runtime Environment (build 1.6.0_31-b05)
Java HotSpot(TM) Client VM (build 20.6-b01, mixed mode, sharing)
 '
Local JDK *NOT* up-to-date: you have  1.6.0_31" , Oracle has  jdk6u37