Short version of classes used in a blog post - full version at https://github.com/alexparvulescu/blog/blob/master/remote-java-install

JSCHWrapper.java

public class JSCHWrapper {

   // just pass private key, user and host
    public JSCHWrapper(String identityFile, String user, String host){ /* .. */ }

    // executes a command
    public String execCommand(String command) throws Exception { /* .. */ }

    // disconnects the current ssh session
    public void disconnect() { /* .. */ }
}

RemoteJavaInstaller.java

public class RemoteJavaInstaller {

    private String getInstallCommand() {
        StringBuilder sb = new StringBuilder();
        sb.append("sudo echo sun-java6-jre shared/accepted-sun-dlj-v1-1 select true | sudo /usr/bin/debconf-set-selections");
        sb.append("; ");
        sb.append("sudo add-apt-repository \"deb http://archive.canonical.com/ lucid partner\"");
        sb.append("; ");
        sb.append("sudo apt-get update");
        sb.append("; ");
        sb.append("sudo apt-get install --yes sun-java6-jdk sun-java6-jre");
        sb.append("; ");
        sb.append("echo \"JAVA_HOME=/usr/lib/jvm/java-6-sun\" >> .bashrc");
        sb.append("; ");
        sb.append("echo \"PATH=\\$PATH:\\$JAVA_HOME/bin\" >> .bashrc");
        sb.append("; ");
        sb.append("java -version");
        sb.append("; ");
        return sb.toString();
    }

    public String install() {
        JSCHWrapper j = null;
        try {
            j = new JSCHWrapper(IDENTITY_FILE, USER, HOST);
            return j.execCommand(getInstallCommand());
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (j != null) {
                j.disconnect();
            }
        }
        return null;
    }

    public static void main(String[] args) throws Exception {
        RemoteJavaInstaller rji = new RemoteJavaInstaller();
        System.out.println(rji.install());
    }
}