The latest impl of Integer.valueOf(String) does not take advantage of the caching capabilities introduced in JDK 1.5.

The impl currently looks as follows:

    public static Integer valueOf(String s) throws NumberFormatException
    {
        return new Integer(parseInt(s, 10));
    }

meaning each invocation will create a new Integer instance.

Why couldn't the impl take advantage of the cache lookup implemented by Integer.valueOf(int), as follows:

    public static Integer valueOf(String s) throws NumberFormatException
    {
        return valueOf((parseInt(s, 10)));
    }

Same is true for java.lang.Long.