What is type-casting? and how can you achieve it?

Type casting in java is to cast one type class or interface to another type i.e.class or interface.superclass variable can't point subclass object in java i.e.can't call method which is declared in subclass.in order to do that you need to cast object back to its original type.
e.g.
suppose two class are First and Second.
Second extends First First f=new Second(); Second s=(Second) f; // typecasting First to Second

is to cast one type to another type

Type casting is a mechanism of converting a reference of an object from one type to another compatible type.
Please note that the underlying object doesn't change.
e.g.
Assume Vehicle is a base class and we have sub classes say LMV and Truck.
Now refer following code Vehicle v = new Truck() // Create a new Truck object and hold it in a Vehicle reference Truck t = (Truck) v; // Even though v holds a Truck object, we cannot directly assign it to a Truck reference //as the reference is higher in hierarchy, so need to cast it.
There are two types of casting.
upcasting and downcasting, casting an object to any of its parent reference is called upcasting e.g.
Object o = t // no need to explictly mentoin the case as Object o = (Object) t as its implicit.
Casting an object reference to a child reference (provided the containing object is of the child type or any of its sub children) is called downcasting.
The earlier example Truck t = (Truck) v is actually downcasting

Type-casting forces an explicit conversion of the type of a value. Type-casting is an operation which takes one operand. It operates on its operand, and returns an equivalent value in the specified type.

Typecasting is nothing but type conversion of the datatype of the source element to the data type of the destination element.Always remember: LHS=RHS.This is an assignment operation.here LHS is the destination and RHS is the source.Type casting is done because the operator(any operator unary or binary) DOES NOT KNOW HOW TO OPERATE WITH2 DIFFERENT DATATYPES.So,this leads to conversion.remember:every datatype will have its own set of unary and binary operators ofcourse same in case of bitwise,relational,logical operators.2 types of typecasting:implicit and explicit.in case of IMPLICIT compiler converts itself.

Type casting: Converting from one type to a different type.
E.g.
string text = new string("2"); int number = Integer.parseint(text); // Integer is a class and parseint is it's object.
-> The typecasting from string to integer using parseint is possible only if string contains a number.
If you try to do so with some text value instead of numeric value, you will end up screwing your compiler.
You cant do the typecasting for the type boolean.

Type casting is of two types Primitive data type casting which involves conversion of int, double, float, boolean etc.
The other type casting is reference type casting or more commonly known as object type casting.
There are brilliant links to understand these concepts on the net.