两个骰子的 Java 总和 - 此代码给出的点数是否超过 6？

Question

public class SumOfTwoDice 
{ 
    public static void main(String[] args) 
    {
        int SIDES = 6;
        int a = 1 + (int) (Math.random() * SIDES);
        int b = 1 + (int) (Math.random() * SIDES);
        int sum = a + b;
        System.out.println(sum);
    }
}

我从 Sedgewick 的在线网站上的“Introduction to Programming with Java”一书中获取了这段代码。

我只是想问 a 或 b 如果碰巧 Math.random( ) 是 1.0？还是我错了？

1.0 * 6 + 1 = 7？

Answer 1

Math.random() 不能返回 1.0，所以 a 或 b 不能是 7。

/**
 * Returns a <code>double</code> value with a positive sign, greater 
 * than or equal to <code>0.0</code> and less than <code>1.0</code>.  <-----------
 * Returned values are chosen pseudorandomly with (approximately) 
 * uniform distribution from that range. 
 * 
 * <p>When this method is first called, it creates a single new
 * pseudorandom-number generator, exactly as if by the expression
 * <blockquote><pre>new java.util.Random</pre></blockquote> This
 * new pseudorandom-number generator is used thereafter for all
 * calls to this method and is used nowhere else.
 * 
 * <p>This method is properly synchronized to allow correct use by
 * more than one thread. However, if many threads need to generate
 * pseudorandom numbers at a great rate, it may reduce contention
 * for each thread to have its own pseudorandom-number generator.
 *  
 * @return  a pseudorandom <code>double</code> greater than or equal 
 * to <code>0.0</code> and less than <code>1.0</code>.
 * @see     java.util.Random#nextDouble()
 */
public static double random();