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Java

Posted by Anoop Kumar
Anoop Kumar
1,715 Points

typecasting in java?

can anyone explain me brief about typecast in java ...i am new in java and a having lot of problem related typecasting ..what is typecasting ? why we typecaste ?etc

1 Answer

Adam Sawicki
Adam Sawicki
15,967 Points
  1. What is typecasting - simply is changing type of REFERENCE to the object. Imagine this
    String a = "example";
    Object b = a;

Now we have 2 references to the same object, but:

    a.charAt(0);
    b.charAt(0);

Second line won't work because b is type Object not type String and Object doesn't have method .charAt();. This is the point where typecasting is useful. Because you know that b is reference to STRING you can typecast

    b=(String)b;
    b.charAt(0);

And now it's all fine.

  1. Example of usage: public void someMethod(Object x){ x = (String)x; x.charAt(0); } In this example you pass to the method a string which is typecasted to Object, but inside the method you want to use it as a String so you need to typecast it to String again.
Anoop Kumar
Anoop Kumar
1,715 Points

thanks a lot