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Usually, when working with numbers in Java, we use primitive data types, such as byte, int, long, double, etc.
- ТHowever, in development, we encounter situations where we need to use objects instead of primitive data types. In order to achieve this, Java provides wrapper classes.
- All shell classes (Integer, Long, Byte, Double, Float, Short) are subclasses of the abstract class of numbers in Java (class Number).
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- The wrapper object contains or wraps its corresponding primitive data type. Converting primitive data types to an object is called wrapping, and the compiler takes care of this.
- Therefore, when using a wrapper class, you simply pass the value of the primitive data type to the constructor of the wrapper class.
- The shell object can be converted back to a primitive data type, and this process is called unpacking.
- The number class is part of the java.lang package.
Here is an example of packaging and unpacking:
- When x is assigned an integer value, the compiler packs an integer, because x is an integer object. Later, it decompresses x so that it can be added as an integer.
Methods of the class of numbers
|1||xxxValue()||It changes the value of an integer object to a xxx data type and returns it.|
|2||compareTo()||Relates an integer object with an argument.|
|3||equals()||Specifies whether the integer is an argument.|
|4||valueOf()||Returns an integer object holding the specified value.|
|5||toString()||Returns a string object (String) that represents the specified int value or an integer object.|
|6||parseInt()||The method is used to take a primitive data type of a specific string.|
|7||abs()||Returns the absolute value of the argument.|
|8||ceil()||It returns lowest double value which is greater than or equal to argument then equivalent to a accurate integer.|
|9||floor()||It returns biggest double value which is less than or equal to argument then equivalent to a accurate integer .|
|10||rint()||The method rint returns the integer that is closest in value to the argument.|
|11||round()||Returns the nearest long or int to the argument according to the rounding rules.|
|12||min()||Returns the smaller of the two arguments.|
|13||max()||Returns the larger of the two arguments.|
|14||exp()||Returns the number e of Euler, raised to the power of a double value.|
|15||log()||Returns the natural logarithm (based on e) with a double value.|
|16||pow()||Returns the value of the initial argument raised to the power of the next argument.|
|17||sqrt()||Returns a suitable rounded positive square root of a double value|
|18||sin()||Returns the sine of the identified double value.|
|19||cos()||Returns the cosine of the identified double value.|
|20||tan()||Returns the tangent of the identified double value.|
|21||asin()||Returns the arcsine of the identified double value.|
|22||acos()||Returns the arc cosine of the identified double value.|
|23||atan()||Returns the arc tangent of the identified double value.|
|24||atan2()||Returns the theta angle from the transformation of rectangular coordinates (x, y) in polar coordinates (g, theta).|
|25||toDegrees()||Converts an angle measured in radians to approximately the equivalent angle measured in degrees.|
|26||toRadians()||Converts the angle measured in degrees to approximately the equivalent angle measured in radians.|
|27||random()||Returns a double value with a positive sign, greater than or equal to 0.0, too less than 1.0.|