how to execute a string expression? e.g. "1.0 / sqrt(sqrt(x))"

[eros]

i'm not sure if the thread's location is correct..
please move it if not appropriate.

I think it is possible to execute a string expression like the Webflow's <evaluate/> tag.

I have dynamic formula to execute. It changes frequently that's why I am planning to put it in xml as <property/> of a <bean/> tag...
then evaluate it, get the result and do other process..

here's image:

xml

	<bean id="computeService"
		class="abs.service.ComputeServiceImpl">
		<property name="expression" value="1.0 / sqrt( sqrt( x1 ) )"/>				
	</bean>

java

public class ComputeServiceImpl implements ComputeService {
	private String expression;
	//getter setter here
	
	@Override
	public BigDecimal compute(BigDecimal x1) {
		// evaluateExpression(String) is sample only
		// the method will be able to evaluate the given expression
		BigDecimal result = evaluateExpression(expression, x1);
		
		// do other computations here
		
		return result;
	}
	
	private BigDecimal evaluateExpression(String expression, BigDecimal input) {
		BigDecimal result;
		
		// code here, it will update the result variable from the given expression
		
		return result;
	}
	
}

sample input/output

// the expression will be: 
//                = 1.0 / Math.sqrt( Math.sqrt( x1.doubleValue() ) )
//                = 0.562341325
BigDecimal result = computeService.compute(BigDecimal.TEN);

System.out.println(result);

>Prints
0.562341325

Thanks in advance.

[eros]

I found one... JEP

Thanks a lot.

[Rossen Stoyanchev]

Web Flow uses Spring EL. It's part of the Spring Framework and is used in many other Spring projects.