java.lang · java.base · since Java 1.0

Double

declaration

public final class Double extends Number
        implements Comparable<Double>, Constable

Immutable box for double plus IEEE-754 utilities: NaN/infinity testing, bit conversion, parsing. The NaN ≠ NaN rule lives here.

Key methods

`static double parseDouble(String s)`	String → double (locale-insensitive — use NumberFormat for user input).
`static boolean isNaN(double) / isInfinite(double)`	The only correct NaN test.
`static int compare(double a, double b)`	Total order: -0.0 < 0.0, NaN greatest.
`static long doubleToLongBits(double)`	Raw IEEE-754 bits — the basis of Double.equals.