[REFRESH] JDK 9 RFR of JDK-8035279: Clean up internal deprecations in BigInteger

[Paul Sandoz]

On Feb 25, 2014, at 9:36 PM, Brian Burkhalter <brian.burkhalter at oracle.com> wrote:

> 
> On Feb 25, 2014, at 4:26 AM, Paul Sandoz wrote:
> 
>> Might as well just remove the @Deprecated stuff. I think it is fine under the circumstances to have offsets and getter methods that return the correct values.
> 
> I have posted a new webrev taking this approach:
> 
> http://cr.openjdk.java.net/~bpb/8035279/webrev.01/
> 
> A review would be appreciated.
> 

It might be worth refining the comments, replacing:

 145     // These "redundant fields" are initialized with recognizable nonsense
 146     // values, and cached the first time they are needed (or never, if they
 147     // aren't needed).

with:

// The following fields are stable variables. A stable variable's value changes
// at most once from the default zero value to a non-zero stable value.
// A stable value is calculated lazily on demand.
// 

     /**
     * One plus the bitCount of this BigInteger. This is a stable variable.
...
    /**
     * One plus the bitLength of this BigInteger. This is a stable variable.
...
    /**
     * Two plus the lowest set bit of this BigInteger. This is a stable variable.

Also, is @serial is relevant any more?


Plus to be pedantic for firstNonzeroIntNumPlusTwo with zero magnitudes:

    /**
     * Two plus the index of the lowest-order int in the magnitude of this
     * BigInteger that contains a nonzero int. This is a stable variable.
     * The least significant int has int-number 0, the next int in order of
     * increasing significance has int-number 1, and so forth.
     *
     * <p>Note: never used for a BigInteger with a magnitude of zero.
     * @see #firstNonzeroIntNum()


    /**
     * Returns the index of the int that contains the first nonzero int in the
     * little-endian binary representation of the magnitude (int 0 is the
     * least significant). If the magnitude is zero, return value is undefined.
     *
     * <p>Note: never used for a BigInteger with a magnitude of zero.
     * @see #getInt.
     */
    private int firstNonzeroIntNum() {
        int fn = firstNonzeroIntNumPlusTwo - 2;
        if (fn == -3) { // firstNonzeroIntNum not initialized yet
            // Search for the first nonzero int
            int i;
            int mlen = mag.length;
            for (i = mlen - 1; i >= 0 && mag[i] == 0; i--)
                ;
            fn = mlen - i - 1;
            firstNonzeroIntNumPlusTwo = fn + 2; // offset by two to initialize
        }
        return fn;
    }

An unnecessary assignment is removed from the above method.

--

We can revisit and clean things up if/when the JMM is updated.

Paul.