mvel - MVEL extracting a string from a string

Question

I have the strings "000134567 - AA - 2001" and "002134567 - AB - 2001" and I want to extract all the numbers before the " - AA". But I only want to return the numbers starting from the first non-zero number. For example, I would want "134567" or "2134567".

Is there some function that would allow me to do this using MVEL? Any help is appreciated.

Answer 1

I do not think directly we can use MVEL for this, but yes tweaking little bit might help us.

import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import org.mvel2.MVEL;
import org.mvel2.ParserContext;
import org.mvel2.integration.VariableResolverFactory;
import org.mvel2.integration.impl.MapVariableResolverFactory;

public class MyTest {
    public static void main(String[] args) {
        String myString = "000134567 - AA - 2001";

        Map contextMap = new HashMap();
        contextMap.put("myString", myString);

        ParserContext ctx = new ParserContext();
        ctx.addPackageImport("java.util.regex");

        Serializable s = MVEL.compileExpression("outputString(myString)", ctx);

        System.out.println(MVEL.executeExpression(s, contextMap, getMvelFactory(contextMap)));
    }

    private static VariableResolverFactory getMvelFactory(Map contextMap) {
        VariableResolverFactory functionFactory = new MapVariableResolverFactory(contextMap);
        MVEL.eval(
                "outputString = def (myString) { java.util.regex.Pattern p = java.util.regex.Pattern.compile(\"[0-9]+\"); java.util.regex.Matcher m = p.matcher(myString); if (m.find()) { String output = m.group(); return output.replaceAll(\"^0+\", \"\");}};",
                functionFactory);
        return functionFactory;
    }
}

Function

Below is my function written in java which i have included inside Mvel VariableResolverFactory.

outputString = def (myString) { 
        java.util.regex.Pattern p = java.util.regex.Pattern.compile("[0-9]+");
        Matcher m = p.matcher(myString);
        if (m.find()) {
            String output = m.group();
            return output.replaceAll("^0+", "");
        }
 };

Creating Parser Context and adding import

Since java.util.regex package is not available with MVEL, so we will import this package explicitly.

    ParserContext ctx = new ParserContext();
    ctx.addPackageImport("java.util.regex");

Compiling Expression using above Import

This will just compile the expression and will add imports for later use while evaluation.

Serializable s = MVEL.compileExpression("outputString(myString)", ctx);

Varying variable

You can pass through your variables as below,

    Map contextMap = new HashMap();
    contextMap.put("myString", myString);

Rest you can change the function body, signature and return statement as per your needs.