How to get VM arguments from inside of Java application?

VM arguments: control knobs for JVM

VM arguments are like the buttons and knobs on an audio mixer. They give you fine control over how the JVM operates and performs.

Harvesting the VM argument fields

Try the RuntimeMXBean class to pull a list of VM arguments:

// What's cooking, JVM?
List<String> vmArguments = ManagementFactory.getRuntimeMXBean().getInputArguments();
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This step grants access to a rich smorgasbord of system properties (-D), memory configurations (-Xmx, -Xms), and garbage collector settings.

StringBuilder: your friendly neighborhood String handler

To process or manipulate these VM argument strings efficiently, the StringBuilder class is the Batman to your Gotham:

// StringBuilder to the rescue!
StringBuilder vmArgsBuilder = new StringBuilder();
vmArguments.forEach(arg -> vmArgsBuilder.append(arg).append(" "));
String vmArgsLine = vmArgsBuilder.toString();
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Remember, with great power comes great responsibility. Carefully parse arguments containing spaces. Tools or libraries may be necessary for accurate parsing.

JMX: a Jedi Master's tool

For super-users out there, the Java Management Extensions (JMX) is your ultimate playground. With JMX, you can bash VM arguments around like a Jedi with a lightsaber - but be warned, using the force requires knowledge!

Thread orchestration by VM options

The presence of specific VM arguments, like -Xss, directly influences how you configure and deploy threads in your code.

Unix systems: a quarry of JVM gems

On Unix-like systems, a combination of Java Native Access (JNA) and /proc inspections can reveal insightful JVM telemetry. Use responsibly (or with joy).

Custom properties: Your secret weapon

For accessing user-defined properties, smash the System.getProperty("name") button:

// Who's the boss?
String customValue = System.getProperty("myCustomProp");
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The returned value will be null if the property wasn't set. A null-check would go a long way here.

Tick-tock! Adapt or perish

Also, it's important to bear in mind that -client or -server JVMs mask certain arguments. Know your battleground, adapt, and conquer!