The Double class is a wrapper class for the primitive type double. It contains several methods for dealing with double values effectively, such as converting them to string representations and vice versa. A Double object can only hold one double value.
There are mainly two constructors to initialize a Double-object
public Double(Double d)
public Double(String s) throws NumberFormatException
Methods | Description |
---|---|
boolean doubleValue() | Returns a primitive double value from a Double wrapper object. |
int compareTo(Double b) | -If the invoked Double object has the same Double value as b, it returns a zero. -Returns a positive value if the value of the invoked Double object is greater than b. -If the invoked object has a smaller value than b, it returns a negative value. |
boolean equals(Object ob) | Returns true if the Double object invoked has the same value as referred by ob, otherwise false. |
static Double parseDouble(String s) | Converts a String value to a primitive double value. |
static Double valueOf(double b) | Returns a Double object after converting it from a primitive Double value b. |
static Double valueOf(String s) | Returns a Double object after converting it from a String s. |
short shortValue() | Returns a primitive short value after converting a Double object to it. |
byte byteValue() | Returns a primitive byte value after converting a Double object to it. |
int intValue() | Returns a primitive int value after converting a Double object to it. |
long longValue() | Returns a primitive long value after converting a Double object to it. |
float floatValue() | Returns a primitive float value after converting a Double object to it. |
boolean isNaN() | If the double object under consideration is not a number, it returns true; otherwise, it returns false. |
hashCode() | It returns the hash code for the given Double object. |
boolean isInfinite() | If the double object under consideration is very large, it returns true; otherwise, it returns false. |
double doubleValue() | Returns a primitive double value after converting a Double object to it. |
public class Coderz
{
public static void main(String[] args)
{
Double d1 = 4d;
Double d2 = 67d;
Double d3 = Double.NaN;
Double d4 = Double.POSITIVE_INFINITY;
// Returns the hashCode.
System.out.println("The hashCode for the number '"+d1+"' is given as :"+ d1.hashCode());
// Returns the integer type value.
System.out.println("The interger type value for the double '"+d2+"' is given as :"+d2.intValue());
// Returns a boolean value
System.out.println("Is the number '"+d3+"' is NaN? :"+d3.isNaN());
// Check whether the number is finitwe or not.
System.out.println("Is the number '"+d2+"' is finite? "+d4.isInfinite());
}
}
The hashCode for the number '4.0' is given as :1074790400
The interger type value for the double '67.0' is given as :67
Is the number 'NaN' is NaN? :true
Is the number '67.0' is finite? true
class Coderz
{
public static void main(String []args)
{
Double d1 = new Double("5.5"); //Constructor accepting String value
Double d2 = new Double(5.5); //Constructor accepting primitive boolean value
System.out.println("Value in d1 = "+d1);
System.out.println("Value in d2 = "+d2);
System.out.println("Invoking "+d1 +"to compare with"+ d2 +": "+ d1.compareTo(d2));
Double d3 = new Double("20.5");
Double d4 = new Double(10.5);
System.out.println("Value in d3 = "+d3);
System.out.println("Value in d4 = "+d4);
System.out.println("Invoking "+d3+" to compare with "+d4 +": "+ d3.compareTo(d4));
System.out.println("Invoking "+d4 +"to compare with "+d3+" : "+ d4.compareTo(d3));
}
}
Value in d1 = 5.5
Value in d2 = 5.5
Invoking 5.5 to compare with 5.5: 0
Value in d3 = 20.5
Value in d4 = 10.5
Invoking 20.5 to compare with 10.5: 1
Invoking 10.5 to compare with 20.5 : -1
class Coderz
{
public static void main(String []args)
{
Double b1 = new Double("100.5ft"); //Passing a String value that is not a valid primitive float value.
}
}
Exception in thread "main" java.lang.NumberFormatException: For input string: "100.5ft"
at java.base/jdk.internal.math.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2054)
at java.base/jdk.internal.math.FloatingDecimal.parseDouble(FloatingDecimal.java:110)at java.base/java.lang.Double.parseDouble(Double.java:543)
at java.base/java.lang.Double.<init>(Double.java:625)
at Coderz.main(Coderz.java:6)
NumberFormatException is raised when we pass String value to the constructor of Double class or its method parseDouble(), which is not a legal double value or it is out-of-range.
Note: also read about the Float class in Java
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Staying up to the mark is what defines me. Hi all! I’m Rabecca Fatima a keen learner, great enthusiast, ready to take new challenges as stepping stones towards flying colors.
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