More about objects in Java - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 128

synchronized protected int next (int bits) {
seed = (seed * 0x5DEECE66DL + 0xBL) & ((1L << 48) - 1);
return (int)(seed >>> (48 - bits));
}
Here the mod operation comes via the AND operation since m in this case has all
47 bits set to 1.
This method is protected (see Section 5.3.3, Access Rules). The public
random number methods accessible by all classes use the next() method. For
example, nextInt() simply includes the statement
return next (32);
The nextLong() method invokes next(32) , shifts the result by 32 bits to the
left, invokes next(32) again and then OR s the two values together to obtain a
64-bit random number:
return ((long)next (32) << 32) + next (32);
The nextFloat() method provides values in the range 0.0f <= x < 1.0f :
return next (24) / ((float)(1 << 24));
The nextDouble() method provides values in the range 0.0d <= x < 1.0d
using the statement
return (((long)next (26) << 27) + next (27))/(double)(1L << 53)
The nextBoolean() method uses the statement
return next (1)!= 0;
See the java.util.Random class specification for more detailed descriptions
of the algorithms used for these and the other next Xxx () methods.
4.10 Improved histogram class
Here we make a subclass of the BasicHist class discussed in Chapter 3.
The class definition below shows that BetterHist inherits from BasicHist ,
obtaining the properties of the latter while providing new capabilities.
Note how the constructor invokes super() to select a constructor in the base
class. Also, we see how the new methods in the subclass can access the data
variables in the base class. (In the next chapter we discuss access modifiers such
as private ,which prevents subclasses from accessing a field or method.)
We add several methods to our histogram that provide various parameters
specifying the histogram. Also, a calculation of the mean and standard deviation
of the distribution in the histogram is included.