Java Programming

Hello everybody,

I am trying to write a piece of java code that will convert a java class to jimple, print the jimple code along withe the line numbers and then give the line numbers for lines with "virtual invoke".

The code that I have written so far looks like below:

import soot.*;
import java.util.*;
import soot.util.*;
import soot.jimple.Stmt;
import soot.tagkit.LineNumberTag;
import soot.baf.*;
import java.io.*;

public class GetStmts4 extends BodyTransformer implements RetInst
{
    private static GetStmts4 instance = new GetStmts4();
    
    private GetStmts4() {};

    public static GetStmts4 v()
    {
	return instance;
    }

    public static void main(String args[])
    {
	soot.options.Options.v().set_keep_line_number(true);
	//soot.options.Options.v().set_whole_program(true);
	//soot.options.Options.v().setPhaseOption("cg","verbose:true");
        PackManager.v().getPack("jtp").add(new Transform ("jtp.annotexample",GetStmts4.v()));
	soot.Main.main(args);
	
    }
    
    protected void internalTransform(Body b, String phaseName, Map options)
    {
	int linenum = 0;
	int count = 0;
	int array[] = new int[20];
	PatchingChain units = b.getUnits();
	Iterator unitsIt = units.iterator();
	
	while(unitsIt.hasNext())
	    {
		Unit unit = (Unit)unitsIt.next();
		LineNumberTag tag = (LineNumberTag) unit.getTag("LineNumberTag");
		RetInst rt = (RetInst)unit;
		int index = rt.getIndex();  // to get the index of the jimple lines ???
		System.out.println("Index is :" + index);
	    	System.out.println(unit);
		if (tag != null)
//the following piece of code gives me the line number but its in the java source code....i need the line numbers of jimple code.
		    {
			System.out.println("java line number:"+tag.getLineNumber());
			//System.out.println("tag name:"+tag.getName());
			String string = unit.toString();
			if(string.matches("\\s*.*virtualinvoke.*"))
			    {
				count++;
				System.out.println("line number with virtualinvoke:"+tag.getLineNumber());
				array[count] = tag.getLineNumber();
				System.out.println("the " +count+ " element in array is : " +array[count]);
			    }
		    }
	    }
	for(int k = 1;k <= count; k++)
	    {
		System.out.println(array[k]);
	    }
	}
 }

So I am getting the following error message:
GetStmts4.java:9: GetStmts4 is not abstract and does not override abstract method setIndex(int) in soot.baf.RetInst
public class GetStmts4 extends BodyTransformer implements RetInst

Thanks!!