Pointer is a reference handle to a memory location. Improper handling of pointers leads to memory leaks and reliability issues hence Java doesn’t support the usage of pointers.
Final is used to apply restrictions on class, method and variable. Final class can’t be inherited, final method can’t be overridden and final variable value can’t be changed.
Finally is used to place important code, it will be executed whether exception is handled or not.
Finalize is used to perform clean up processing just before object is garbage collected.
If you want a class to contain a particular method but you want the actual implementation of that method to be determined by child classes, you can declare the method in the parent class as abstract.
These are classes that allow primitive types to be accessed as objects.
Example: Integer, Character, Double, Boolean etc.
The Java platform differs from most other platforms in the sense that it’s a software-based platform that runs on top of other hardware-based platforms.It has two components:
API(Application Programming Interface)
When we create string with new() Operator, it’s created in heap and not added into string pool while String created using literal are created in String pool itself which exists in PermGen area of heap.
String s = new String(“Test”);
does not put the object in String pool , we need to call String.intern() method which is used to put them into String pool explicitly. its only when you create String object as String literal e.g. String s = “Test” Java automatically put that into String pool. ( Ericsson JAVA interview questions )
Finally is the block of code that executes always. The code in finally block will execute even if an exception is occurred. Finally block is NOT called in following conditions
If the JVM exits while the try or catch code is being executed, then the finally block may not execute. This may happen due to System.exit() call.
if the thread executing the try or catch code is interrupted or killed, the finally block may not execute even though the application as a whole continues.
If a exception is thrown in finally block and not handled then remaining code in finally block may not be executed.
Platform independence me that we can write and compile the java code in one platform (eg Windows) and can execute the class in any other supported platform eg (Linux,Solaris,etc).
An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior and all methods are implicitly abstract. An interface has all public members and no implementation.