How are Observer and Observable used?

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Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.

2013-06-05, 1883👍, 0💬

Is it necessary that each try block must be followed by a catch block?
Is it necessary that each try block must be followed by a catch block? It is not necessary that each try block must be followed by a catch block. It should be followed by either a catch block OR a finally block. And whatever exceptions are likely to be thrown should be declared in the throws clause ... 2013-06-03, 3268👍, 0💬

How does Java handle integer overflows and underflows?
How does Java handle integer overflows and underflows? It uses those low order bytes of the result that can fit into the size of the type allowed by the operation. 2013-06-06, 2507👍, 0💬

When a thread is created and started, what is its initial state?
When a thread is created and started, what is its initial state? A thread is in the ready state after it has been created and started. 2013-06-07, 2230👍, 0💬

If I write return at the end of the try block, will the finally block still execute?
If I write return at the end of the try block, will the finally block still execute? Yes even if you write return as the last statement in the try block and no exception occurs, the finally block will execute. The finally block will execute and then the control return. 2013-06-04, 2192👍, 0💬

Does garbage collection guarantee that a program will not run out of memory?
Does garbage collection guarantee that a program will not run out of memory? Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create obje... 2013-06-06, 1899👍, 0💬

How are Observer and Observable used?
How are Observer and Observable used? Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by obje... 2013-06-05, 1884👍, 0💬

What are the different ways to handle exceptions?
What are the different ways to handle exceptions? There are two ways to handle exceptions, 1. By wrapping the desired code in a try block followed by a catch block to catch the exceptions. and 2. List the desired exceptions in the throws clause of the method and let the caller of the method hadle th... 2013-05-31, 1881👍, 0💬

What is synchronization and why is it important?
What is synchronization and why is it important? With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of... 2013-06-05, 1852👍, 0💬

What is the basic difference between the 2 approaches to exception handling.
520. What is the basic difference between the 2 approaches to exception handling. 1. try catch block and 2. specifying the candidate exceptions in the throws clause? When should you use which approach? In the first approach as a programmer of the method, you urself are dealing with the exception. Th... 2013-06-03, 1831👍, 0💬

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