Data Types - Beginning Java 8 Fundamentals - page 77

All real numbers are called double literals. A double literal may optionally end with d or D , for example, 19.27d.
However, the suffix d or D is optional in double literals. That is, both 19.27 and 19.27d represent the same double literal.
This topic uses double literals without the suffix d or D . A double literal can be expressed in the following two formats:

• Decimal number format

•
Examples of double literals in decimal number format are as follows:

Scientific notation

double d1 = 8D
double d2 = 8.;
double d3 = 8.0;
double d4 = 8.D;
double d5 = 78.9867;
double d6 = 45.0;

■ Tip 8 is an int literal whereas 8D , 8. , and 8.0 are double literals.

Like a float literal, you can also use scientific notation to express double literals.

double d1 = 32.5E-1;
double d2 = 0.325E+1;
double d3 = 0.325E1;
double d4 = 0.0325E2;
double d5 = 0.0325e2;
double d6 = 32.5E-1D;
double d7 = 0.325E+1d;
double d8 = 0.325E1d;
double d9 = 0.0325E2d;

Like the float data type, the double data type defines two zeros, two infinities, and a NaN . They are represented by
constants in the Double class. Table 3-4 lists these constants and their meanings. Table 3-4 also lists two constants, which
represent the maximum and minimum (greater than zero) double values that can be represented in a double variable.

Table 3-4. double Constants in the Double Class

double Constants Meaning

Double.POSITIVE_INFINITY

Positive infinity of type double

Double.NEGATIVE_INFINITY

Negative infinity of type double

Double.NaN

Not a Number of type double

Double.MAX_VALUE

The largest positive value that can be represented in a double variable. This is equal
to 1.7 x 10 308 (approx.)

Double.MIN_VALUE

The smallest positive value greater than zero that can be represented in a double
variable. This is equal to 4.9 x 10 -324 .