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860. extends is for extending a class. implements is for implementing an interface. The difference between an interface and a regular class is that in an interface you can not implement any of the declared methods. Only the class that "implements" the interface can implement the methods. The C++ equivalent of an interface would be an abstract ...
Feb 12, 2009 · 4. One difference between implementing Runnable and extending Thread is that by extending Thread, each of your threads has a unique object associated with it, whereas implementing Runnable, many threads can share the same object instance. A class that implements Runnable is not a thread and just a class.
Aug 12, 2010 · 28. Those are two very different things. Importing a class, is making it so you can use that class without needing to qualify the full name in the current class you are writing. Extending a class is creating a new class that is a subclass of some other class. This will allow you to add or change functionality of the class you are extending.
Mar 3, 2012 · Java does not allow you to extend multiple classes. This avoids some problems related to multiple inheritance. However you can choose to implement multiple interfaces. This is a huge plus. Some people also believe extends decreases the flexibility of their code. However, I doubt there is any huge difference in performance, efficiency etc.
There is a rule in java if want to implement an interface and extend a class we must extend a class first then we implement an interface. interface A{} class super{} class sub extends super implements A {} When the Java compiler turns a class into bytecode, it must first look to a parent class. That is because the underlying implementation of ...
@Anand - See the 3rd bullet under PECS above. You'll probably need to use a specific generic parameters (no wildcard, e.g. List<T>).
Yes, you can able to declare extends and implements together. But one condition you have to declare extends before implements keyword. example. public class Dog extends Animal implements Interface1,Interface2. {. //you should implement all methods here... } answered Jul 30, 2023 at 14:27.
21. Although <?> is supposed to be a shortcut for <? extend object>, there is a tiny difference between the two. <?> is reifiable while <? extend object> is not. The reason they did this is to make it easier to distinguish reifiable type. Anything that looks like <? extends something>, <T>, <Integer> are nonreifiable.
Jan 23, 2013 · It is always recommended to implement Runnable rather than extend Thread as implementing Runnable would force you to implement run() method. extending Thread wouldn't force you as Thread class it self implements run method. also as java doesn't support multiple inheritence using class's when your class is already extending another class and you need Threading in your class implementing Runnable is the way to go in such scenarios
Oct 30, 2012 · Any object that implements java.lang.AutoCloseable, which includes all objects which implement java.io.Closeable, can be used as a resource. The following example reads the first line from a file. It uses an instance of BufferedReader to read data from the file. BufferedReader is a resource that must be closed after the program is finished with it:
