MersenneTwister for Java

import java.math.BigInteger;

public class MersenneTwister {
    private static final int N = 624;
    private static final int M = 397;
    private static final int MATRIX_A = 0x9908b0df;
    private static final int UPPER_MASK = 0x80000000;
    private static final int LOWER_MASK = 0x7fffffff;

    private int[] mt;
    private int mti;

    public MersenneTwister(int seed) {
        mt = new int[N];
        mt[0] = seed;
        for (mti = 1; mti < N; mti++) {
            mt[mti] = (1812433253 * (mt[mti - 1] ^ (mt[mti - 1] >> 30)) + mti);
        }
    }

    public int nextInt() {
        if (mti >= N) {
            int i;
            for (i = 0; i < N - M; i++) {
                int x = (mt[i] & UPPER_MASK) | (mt[i + 1] & LOWER_MASK);
                mt[i] = mt[i + M] ^ (x >> 1) ^ ((x & 1) * MATRIX_A);
            }
            for (; i < N - 1; i++) {
                int x = (mt[i] & UPPER_MASK) | (mt[i + 1] & LOWER_MASK);
                mt[i] = mt[i + (M - N)] ^ (x >> 1) ^ ((x & 1) * MATRIX_A);
            }
            int x = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
            mt[N - 1] = mt[M - 1] ^ (x >> 1) ^ ((x & 1) * MATRIX_A);
            mti = 0;
        }
        int y = mt[mti++];
        y ^= (y >> 11);
        y ^= (y << 7) & 0x9d2c5680;
        y ^= (y << 15) & 0xefc60000;
        y ^= (y >> 18);
        return y;
    }

    public double nextDouble() {
        long l = ((long) nextInt() << 32) + nextInt();
        return ((double) (l & 0x7fffffffffffffffL)) / ((double) 0x8000000000000000L);
    }

    public BigInteger nextBigInteger(int bitLength) {
        return new BigInteger(bitLength, this);
    }
}