Double

Double

java.lang

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Java 1.0

serializable comparable

This class provides an immutable object wrapper around the double primitive data type. doubleValue( ) returns the primitive double value of a Double object, and there are other methods (which override Number methods and whose names all end in "Value") for returning a the wrapped double value as a variety of other primitive types.

This class also provides some useful constants and static methods for testing double values. MIN_VALUE and MAX_VALUE are the smallest ( closest to zero) and largest representable double values. POSITIVE_INFINITY and NEGATIVE_INFINITY are the double representations of infinity and negative infinity, and NaN is special double "not a number" value. isInfinite( ) in class and instance method forms tests whether a double or a Double has an infinite value. Similarly, isNaN( ) tests whether a double or Double is not-a-number ; this is a comparison that cannot be done directly because the NaN constant never tests equal to any other value, including itself.

The static parseDouble( ) method converts a String to a double . The static valueOf( ) converts a String to a Double , and is basically equivalent to the Double( ) constructor that takes a String argument. The static and instance toString( ) methods perform the opposite conversion: they convert a double or a Double to a String . See also java.text.NumberFormat for more flexible number parsing and formatting.

The compareTo( ) method makes Double object Comparable which is useful for ordering and sorting. The static compare( ) method is similar (its return values have the same meaning as those of Comparable.compareTo( ) ) but works on primitive values rather than objects and is useful when ordering and sorting arrays of double values.

doubleToLongBits( ) , doubleToRawBits( ) and longBitsToDouble( ) allow you to manipulate the bit representation (defined by IEEE 754) of a double directly (which is not something that most applications ever need to do).

Figure 10-17. java.lang.Double

 public final class  Double  extends Number implements Comparable<Double> {  // Public Constructors  public  Double  (String  s  ) throws NumberFormatException;        public  Double  (double  value  );  // Public Constants  public static final double  MAX_VALUE  ;  =1  .7976931348623157E308      public static final double  MIN_VALUE  ;  =4  .9E-324      public static final double  NaN  ;  =  NaN      public static final double  NEGATIVE_INFINITY  ;  =-  Infinity      public static final double  POSITIVE_INFINITY  ;  =  Infinity  5.0  public static final int  SIZE  ;  =64   1.1  public static final Class<Double>  TYPE  ;  // Public Class Methods   1.4  public static int  compare  (double  d1  , double  d2  );        public static long  doubleToLongBits  (double  value  );  native   1.3  public static long  doubleToRawLongBits  (double  value  );  native  public static boolean  isInfinite  (double  v  );        public static boolean  isNaN  (double  v  );        public static double  longBitsToDouble  (long  bits  );  native   1.2  public static double  parseDouble  (String  s  ) throws NumberFormatException;  5.0  public static String  toHexString  (double  d  );        public static String  toString  (double  d  );        public static Double  valueOf  (String  s  ) throws NumberFormatException;  5.0  public static Double  valueOf  (double  d  );  // Public Instance Methods  public boolean  isInfinite  ( );        public boolean  isNaN  ( );  // Methods Implementing Comparable   1.2  public int  compareTo  (Double  anotherDouble  );  // Public Methods Overriding Number   1.1  public byte  byteValue  ( );        public double  doubleValue  ( );        public float  floatValue  ( );        public int  intValue  ( );        public long  longValue  ( );  1.1  public short  shortValue  ( );  // Public Methods Overriding Object  public boolean  equals  (Object  obj  );        public int  hashCode  ( );        public String  toString  ( );   }