import java.util.Map;
import java.util.HashMap;
...

( in the method using Vnano Engine )

// Create a Map for storing option names/values (option map).
Map<String, Object> optionMap = new HashMap<String, Object>();

// Enable the option handling integer literals as floating point numbers.
optionMap.put("EVAL_INT_LITERAL_AS_FLOAT", true);

// Enable the option restricting types of operands to only floating point numbers.
optionMap.put("EVAL_ONLY_FLOAT", true);

// Enable the option restricting types of statements to only expressions.
optionMap.put("EVAL_ONLY_EXPRESSION", true);

// Set to the instance of Vnano Engine.
try {
	engine.setOptionMap(optionMap);
} catch (VnanoException e) {
	System.err.println("Incorrect option settings have been detected.");
	e.printStackTrace();
}