Java隨機數Random出來是固定值

Random以種子爲參考進行一系列操作，所以在設置了種子時next的結果是固定值

如下：
在進行實例化Random時，如果使用空構造，則會使用隨機種子（seed）；如果提供了初始的seed，則會使用提供的seed。
在進行next操作時seed會更新

public Random() {
    this(seedUniquifier() ^ System.nanoTime());
}
public Random(long seed) {
    if (getClass() == Random.class)
        this.seed = new AtomicLong(initialScramble(seed));
    else {
        // subclass might have overriden setSeed
        this.seed = new AtomicLong();
        setSeed(seed);
    }
}

protected int next(int bits) {
    long oldseed, nextseed;
    AtomicLong seed = this.seed;
    do {
        oldseed = seed.get();
        nextseed = (oldseed * multiplier + addend) & mask;
    } while (!seed.compareAndSet(oldseed, nextseed));
    return (int)(nextseed >>> (48 - bits));
}

public static void main(String[] args) {
    Random random = new Random();

    System.out.println(random.nextLong());
    System.out.println(random.nextLong());
    System.out.println(random.nextLong());

    System.out.println("=========");

    random = new Random(10000);

    System.out.println(random.nextLong());
    System.out.println(random.nextLong());
    System.out.println(random.nextLong());

    System.out.println("=========");

    System.out.println(new Random(10000).nextLong());
    System.out.println(new Random(10000).nextLong());
    System.out.println(new Random(10000).nextLong());

    System.out.println("=========");

    System.out.println(new Random().nextLong());
    System.out.println(new Random().nextLong());
    System.out.println(new Random().nextLong());
}

3923360040953814112
566949543387758225
4041590311002156335
=========
-2141912560879618632
8344340767467600327
6822250609460363149
=========
-2141912560879618632
-2141912560879618632
-2141912560879618632
=========
-4845906680549806302
-26037007999465399
-558189642984715119

Process finished with exit code 0