Type casting

Type casting

• 1.
  Type Casting Typesof Data Types Primitive or Fundamental Data Types Referenced or Advanced Data Types Casting Primitive Data Type •Widening: Converting a lower data type into higher data type is called widening. •Narrowing: Converting a higher data type into lower data type is called narrowing byte short char int long float double
• 2.
  Type Casting… Wideningin Primitive Data Types: char ch = ‘A’; int num = (int) ch; int x = 9500; float sal = (float) x; Note: Widening is safe because there will not be any loss of data. That is why, compiler does the casting internally and hence this is called “Implicit Casting”.
• 3.
  Type Casting… Narrowingin Primitive Data Types: int x = 66; char ch = (char) x; double d = 12.6789; int n = (int) d; Note: Narrowing is not safe because there will be loss of data. That is why, compiler forces the programmer to use cast operator and hence this is called “Explicit Casting”.
• 4.
  Type Casting… CastingReferenced Data Types: A class is a referenced data type. Converting a class type into another class type is also possible through casting. But the classes should have the same relationship between them by the way of inheritance. University College Department
• 5.
  Type Casting… Generalization:Generalization is a phenomenon where a sub class is promoted to a super class, and hence becomes more general. It needs widening or up-casting. Specialization: Specialization is a phenomenon where a super class is narrowed down to a sub class. It needs narrowing or down-casting.
• 6.
  Widening in referenceddata type class One { void show1() { System.out.println("I am class one"); } } class Two extends One { void show1() { System.out.println("I am class Two"); } } class Test { public static void main(String args[]) { One o; o = (One) new Two(); o.show1(); } } Note: we are able to access show1() method of the super class. But in this case, it is not possible to call show2().