Computer programming 2 Lesson 10

Computer programming 2 Lesson 10

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  Computer Programming 2 Lesson 10–Java –Numbers Class Prepared by: Analyn G. Regaton
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  NUMBER CLASS Normally, when wework with Numbers, we use primitive data types such as byte, int, long, double, etc. Example int i = 5000; float gpa = 13.65f; double mask = 125; However, in development, we come across situations where we need to use objects instead of primitive data types. In order to achieve this, Java provides wrapper classes. All the wrapper classes (Integer, Long, Byte, Double, Float, Short) are subclasses of the abstract class Number.
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  DIAGRAM Converting primitive datatypes into object is called boxing, and this is taken care by the compiler. The Number class is part of the java.lang package.
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  EXAMPLE PROGRAM 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); } } Output 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.
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  NUMBER METHOD Sr.No. Method &Description 1 xxxValue() Converts the value of this Number object to the xxx data type and returns it. 2 compareTo() Compares this Number object to the argument. 3 equals() Determines whether this number object is equal to the argument. 4 valueOf() Returns an Integer object holding the value of the specified primitive. 5 toString() Returns a String object representing the value of a specified int or Integer. 6 parseInt() This method is used to get the primitive data type of a certain String.
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  NUMBER METHOD 7 abs() Returns theabsolute value of the argument. 8 ceil() Returns the smallest integer that is greater than or equal to the argument. Returned as a double. 9 floor() Returns the largest integer that is less than or equal to the argument. Returned as a double. 10 rint() Returns the integer that is closest in value to the argument. Returned as a double. 11 round() Returns the closest long or int, as indicated by the method's return type to the argument. 12 min() Returns the smaller of the two arguments. Sr.No. Method & Description
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  NUMBER METHOD 13 max() Returns thelarger of the two arguments. 14 exp() Returns the base of the natural logarithms, e, to the power of the argument. 15 log() Returns the natural logarithm of the argument. 16 pow() Returns the value of the first argument raised to the power of the second argument. 17 sqrt() Returns the square root of the argument. 18 sin() Returns the sine of the specified double value. 19 cos() Returns the cosine of the specified double value. Sr.No. Method & Description
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  NUMBER METHOD 20 tan() Returns thetangent of the specified double value. 21 asin() Returns the arcsine of the specified double value. 22 acos() Returns the arccosine of the specified double value. 23 atan() Returns the arctangent of the specified double value. 24 atan2() Converts rectangular coordinates (x, y) to polar coordinate (r, theta) and returns theta. 25 toDegrees() Converts the argument to degrees. 26 toRadians() Converts the argument to radians. 27 random() Returns a random number. Sr.No. Method & Description
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  xxxValue() Method The method convertsthe value of the Number Object that invokes the method to the primitive data type that is returned from the method. Syntax Here is a separate method for each primitive data type − byte byteValue() short shortValue() int intValue() long longValue() float floatValue() double doubleValue() Parameters Here is the detail of parameters − •All these are default methods and accepts no parameter. Return Value •This method returns the primitive data type that is given in the signature.
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  EXAMPLE PROGRAM Output 5 5.0 5
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  compareTo() Method The method comparesthe Number object that invoked the method to the argument. It is possible to compare Byte, Long, Integer, etc. However, two different types cannot be compared, both the argument and the Number object invoking the method should be of the same type. Syntax public int compareTo( NumberSubClass referenceName ) Parameters Here is the detail of parameters − •referenceName − This could be a Byte, Double, Integer, Float, •Long, or Short. Return Value •If the Integer is equal to the argument then 0 is returned. •If the Integer is less than the argument then -1 is returned. •If the Integer is greater than the argument then 1 is returned.
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  EXAMPLE PROGRAM public class Test{ public static void main(String args[]) { Integer x = 5; System.out.println(x.compareTo(3)); System.out.println(x.compareTo(5)); System.out.println(x.compareTo(8)); } } This will produce the following result − Output -1 0 1
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  equals() Method The method determineswhether the Number object that invokes the method is equal to the object that is passed as an argument. Syntax public boolean equals(Object o) Parameters Here is the detail of parameters − •Any object. Return Value •The method returns True if the argument is not null and is an object of the same type and with the • same numeric value. There are some extra requirements for Double and Float objects that are described in the Java API documentation.
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  EXAMPLE PROGRAM public class Test{ public static void main(String args[]) { Integer x = 5; Integer y = 10; Integer z =5; Short a = 5; System.out.println(x.equals(y)); System.out.println(x.equals(z)); System.out.println(x.equals(a)); } } Output False true false
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  valueOf() Method The valueOf methodreturns the relevant Number Object holding the value of the argument passed. The argument can be a primitive data type, String, etc. This method is a static method. The method can take two arguments, where one is a String and the other is a radix. Syntax Following are all the variants of this method − static Integer valueOf(int i)static Integer valueOf(String s)static Integer valueOf(String s, int radix) Parameters Here is the detail of parameters − •i − An int for which Integer representation would be returned. •s − A String for which Integer representation would be returned. •radix − This would be used to decide the value of returned Integer based on the passed String. Return Value •valueOf(int i) − This returns an Integer object holding the value of the specified primitive. •valueOf(String s) − This returns an Integer object holding the value of the specified string representation. •valueOf(String s, int radix) − This returns an Integer object holding the integer value of the specified string representation, parsed with the value of radix.
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  EXAMPLE PROGRAM public class Test{ public static void main(String args[]) { Integer x =Integer.valueOf(9); Double c = Double.valueOf(5); Float a = Float.valueOf("80"); Integer b = Integer.valueOf("444",16); System.out.println(x); System.out.println(c); System.out.println(a); System.out.println(b); } } Output 95.0 80.0 10 92
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  toString() Method The method isused to get a String object representing the value of the Number Object. If the method takes a primitive data type as an argument, then the String object representing the primitive data type value is returned. If the method takes two arguments, then a String representation of the first argument in the radix specified by the second argument will be returned. Syntax Following are all the variants of this method − String toString()static String toString(int i) Parameters Here is the detail of parameters − •i − An int for which string representation would be returned. Return Value •toString() − This returns a String object representing the value of this Integer. •toString(int i) − This returns a String object representing the specified integer.
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  EXAMPLE PROGRAM public class Test{ public static void main(String args[]) { Integer x = 5; System.out.println(x.toString()); System.out.println(Integer.toString(12)); } } Output 5 12