Touring Language APIs - Beginning Java 7 - page 328

System.out.println(d1.equals(d2));
System.out.println(+0.0 == -0.0);
}
}
Compile Listing4-5 ( javac FloatDoubleDemo.java )andrunthisapplication
( java FloatDoubleDemo ).Thefollowingoutputprovesthat Float 's equals()
method properly handles NaN and Double 's equals() method properly handles
+/-0.0:
NaN
NaN
true
false
0.0
-0.0
false
true
Tip If you want to test a float or double value for equality with +infinity
or -infinity (but not both), do not use isInfinite() . Instead, compare the value
with NEGATIVE_INFINITY or POSITIVE_INFINITY via == .Forexample, f ==
Float.NEGATIVE_INFINITY .
Youwillfind parseFloat() and parseDouble() usefulinmanycontexts.For
example, Listing 4-6 uses parseDouble() to parse command-line arguments into
double s.
Listing 4-6. Parsing command-line arguments into double precision floating-point values
class Calc
{
public static void main(String[] args)
{
if (args.length != 3)
{
System.err.println("usage: java Calc value1 op
value2");