UseCompressedOops ergonomics for Oracle/Sun JDK 6 on x64

CheckCompressedOopsMode.java

import java.io.*;
import java.lang.management.*;
import com.sun.management.*;

public class CheckCompressedOopsMode {
  private static final String HOTSPOT_BEAN_NAME = "com.sun.management:type=HotSpotDiagnostic";
  private static HotSpotDiagnosticMXBean hotspotMBean;
  
  private static HotSpotDiagnosticMXBean getHotSpotMBean() {
    if (hotspotMBean == null) {
      try {
        hotspotMBean = ManagementFactory.newPlatformMXBeanProxy(
          ManagementFactory.getPlatformMBeanServer(),
          HOTSPOT_BEAN_NAME,
          HotSpotDiagnosticMXBean.class);
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    return hotspotMBean;
  }
  
  public static String getJavaVersion() {
    return System.getProperty("java.version");
  }
  
  public static void printJavaVersionOn(PrintStream out) {
    out.println(getJavaVersion());
  }
  
  public static String getJvmVersion() {
    return System.getProperty("java.vm.name") + " " + System.getProperty("java.vm.version");
  }
  
  public static void printJvmVersionOn(PrintStream out) {
    out.println(getJvmVersion());
  }
  
  public static VMOption getUseCompressedOopsVMOption() {
    return getHotSpotMBean().getVMOption("UseCompressedOops");
  }
  
  public static boolean isUseCompressedOops() {
    return Boolean.valueOf(getUseCompressedOopsVMOption().getValue());
  }
  
  public static void printCompressedOopsModeOn(PrintStream out) {
    try {
      VMOption op = getUseCompressedOopsVMOption();
      out.println("Using compressed oops: " + op.getValue() + 
                    ", origin: " + op.getOrigin());
    } catch (IllegalArgumentException e) {
      out.println("This VM doesn't support UseCompressedOops");
    } catch (NullPointerException e) {
      out.println("This VM doesn't support UseCompressedOops");
    }
  }
  
  public static void main(String[] args) {
    PrintStream out = System.out;
    printJavaVersionOn(out);
    printJvmVersionOn(out);
    printCompressedOopsModeOn(out);
  }
}

command_prompt

$ jdk/6u17_x64/bin/java Che17_x64/bin/java CheckCompressedOopsMode
1.6.0_17
Java HotSpot(TM) 64-Bit Server VM 14.3-b01
Using compressed oops: false, origin: DEFAULT
$ jdk/6u18_x64/bin/java CheckCompressedOopsMode
1.6.0_18
Java HotSpot(TM) 64-Bit Server VM 16.0-b13
Using compressed oops: false, origin: DEFAULT
$ jdk/6u19_x64/bin/java CheckCompressedOopsMode
1.6.0_19
Java HotSpot(TM) 64-Bit Server VM 16.2-b04
Using compressed oops: false, origin: DEFAULT
$ jdk/6u20_x64/bin/java CheckCompressedOopsMode
1.6.0_20
Java HotSpot(TM) 64-Bit Server VM 16.3-b01
Using compressed oops: false, origin: DEFAULT
$ jdk/6u21_x64/bin/java CheckCompressedOopsMode
1.6.0_21
Java HotSpot(TM) 64-Bit Server VM 17.0-b17
Using compressed oops: false, origin: DEFAULT
$ jdk/6u22_x64/bin/java CheckCompressedOopsMode
1.6.0_22
Java HotSpot(TM) 64-Bit Server VM 17.1-b03
Using compressed oops: false, origin: DEFAULT
$ jdk/6u23_x64/bin/java CheckCompressedOopsMode
1.6.0_23
Java HotSpot(TM) 64-Bit Server VM 19.0-b09
Using compressed oops: true, origin: ERGONOMIC
$ jdk/6u24_x64/bin/java CheckCompressedOopsMode
1.6.0_24
Java HotSpot(TM) 64-Bit Server VM 19.1-b02
Using compressed oops: true, origin: ERGONOMIC

Can't use jinfo -flag {flag name} pid to inspect the vm args?