Eclipse debug can not step into (or F5)

Question

package com.test;

import java.util.TreeMap;

public class Main {
    public static void main(String[] args) throws Exception {
        TreeMap<String, String> tree = new TreeMap<String, String>();
        tree.put("1", "1");//line a
        tree.put("1", "1");//line b
        System.out.println(tree.size());
    }
}

I want to debug TreeMap put method, so i add two breakpoints for the lines (line a,line b). Eclipse debug tool cannot step into put mentod when debugging.

I have attached source code for eclipse. when i put mouse over put method, press F3 key, it can go to TreeMap put method source code. I am running Eclipse SDK Version: 3.2.2

Answer 1

download the source code from this link : http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/util/TreeMap.java and then attach this source into eclipse