float « Java Source And Data Type « SCJP

1.11.1.The two floating-point types are float and double
1.11.2.A floating-point literal with a decimal point
1.11.3.A floating-point literal with letter E or e (scientific notation)
1.11.4.A floating-point literal with suffix F or f, indicating a float literal
1.11.5.Special floating-point values.
1.11.6.Two NaN values are defined in the java.lang package (Float.NaN and Double.NaN)
1.11.7.NaN values are non-ordinal for comparisons.
1.11.8.Use Float.isNaN(float) or Double.isNaN(double) to check NaN value