Usually, while we labor with Numbers, we employ ancient data types such as byte, int, long, double, etc.
int i = 5000; float gpa = 13.65; double mask = 0xaf;
However, in expansion, we approach across circumstances where we call for utilizing objects instead of ancient data types. In order to realize this, Java gives wrapper classes.
All the wrapper classes (Integer, Long, Byte, Double, Float, Short) are subclasses of the abstract class Number.
The entity of the covering class holds or wraps its individual primordial data type. Converting primordial data types into entities is called boxing, and this is taken in mind by the compiler. Consequently, while with a wrapper class you now need to bypass the value of the primeval data type to the constructor of the Wrapper set.
In addition, the Wrapper object will be exchanged back to a prehistoric data type, and this course is called unboxing. The Number class is a division of java.lang package.
Following is an example of boxing and unboxing:
public class Test { public static void main(String args[]) { Integer x = 5; // boxes int to an Integer object x = x + 10; // unboxes the Integer to a int System.out.println(x); } }
This will produce the following result −
15
When x is assigned an integer value, the compiler boxes the integer because x is integer object. Later, x is unboxed so that they can be added as an integer.
Following is the list of the instance methods that all the subclasses of the Number class implements −
Sr.No. | Method & Description |
1 | Converts the value of this Number object to the xxx data type and returns it. |
2 | Compares this Number object to the argument. |
3 | Determines whether this number object is equal to the argument. |
4 | Returns an Integer object holding the value of the specified primitive. |
5 | Returns a String object representing the value of a specified int or Integer. |
6 | This method is used to get the primitive data type of a certain String. |
7 | Returns the absolute value of the argument. |
8 | Returns the smallest integer that is greater than or equal to the argument. Returned as a double. |
9 | Returns the largest integer that is less than or equal to the argument. Returned as a double. |
10 | Returns the integer that is closest in value to the argument. Returned as a double. |
11 | Returns the closest long or int, as indicated by the method's return type to the argument. |
12 | Returns the smaller of the two arguments. |
13 | Returns the larger of the two arguments. |
14 | Returns the base of the natural logarithms, e, to the power of the argument. |
15 | Returns the natural logarithm of the argument. |
16 | Returns the value of the first argument raised to the power of the second argument. |
17 | Returns the square root of the argument. |
18 | Returns the sine of the specified double value. |
19 | Returns the cosine of the specified double value. |
20 | Returns the tangent of the specified double value. |
21 | Returns the arcsine of the specified double value. |
22 | Returns the arccosine of the specified double value. |
23 | Returns the arctangent of the specified double value. |
24 | Converts rectangular coordinates (x, y) to polar coordinate (r, theta) and returns theta. |
25 | Converts the argument to degrees. |
26 | Converts the argument to radians. |
27 | Returns a random number |
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