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When an interface method is implemented in a class it must be declared as?
Abstract type
Simple example in interface?
Any device or construct that allows a human being to interact with a machine is an interface. The steering wheel of a car is an interface, the play button on a DVD video player is an interface, the close icon on a window is an interface, the CTRL+C accelerator is an interface, and so on.
What happens if a class doesn't implement all the methods defined in the interface?
It depends on how the class is declared.If the class is a normal class - Then the compiler will complain. All the methods in an interface must be implemented by the class to successfully compile the classIf the class is declared as abstract - Then the compiler will ignore the fact that a few methods are not implemented
Which package in java is treated as default package?
java.lang defines the core Java language, without which all of Java would fail to operate. It is therefore the default package that must be used with every program that will run Java, as it contains all of the logic necessary for exception handling, threads, classes that represent primitives (and their associated logic), and so on.
What is a predefined interface in java?
An interface is a collection of methods that must be implemented by the implementing class.An interface defines a contract regarding what a class must do, without saying anything about how the class will do it.Interface can contain declaration of methods and variables.implementing class must define all the methods declared in the interfaceIf a class implements an interface and does not implement all the methods then class itself must be declared as abstractVariables in interface automatically become static and final variableof the implementing classMembers of interface are implicitly public, so need not be declared as public.An interface must be implemented in class.
What method must be implemented by all Threads?
The "run" method.
When an interface method is implemented in a class it must be declared as?
Abstract type
When to use interface?
Interfaces are a way of imposing a type of functionality on all other java classes that are created using it. It is kind of a template that all child classes using this template must follow. All methods that are declared in an interface must be implemented by the child classes and hence the functionality offered by these classes can be controlled using them. Interfaces are a powerful tool that java provides to achieve multiple inheritance.
Why is interfaces used in java?
Interfaces are a way of imposing a type of functionality on all other java classes that are created using it. It is kind of a template that all child classes using this template must follow. All methods that are declared in an interface must be implemented by the child classes and hence the functionality offered by these classes can be controlled using them. Interfaces are a powerful tool that java provides to achieve multiple inheritance.
Simple example in interface?
Any device or construct that allows a human being to interact with a machine is an interface. The steering wheel of a car is an interface, the play button on a DVD video player is an interface, the close icon on a window is an interface, the CTRL+C accelerator is an interface, and so on.
What happens if a class doesn't implement all the methods defined in the interface?
It depends on how the class is declared.If the class is a normal class - Then the compiler will complain. All the methods in an interface must be implemented by the class to successfully compile the classIf the class is declared as abstract - Then the compiler will ignore the fact that a few methods are not implemented
In Java can an interface be final?
No. Interfaces themselves cannot be instantiated, so in order to be useful you must make a subclass. The final keyword will make a class unable to be extended, which would defeat the point of using an interface.
Which package in java is treated as default package?
java.lang defines the core Java language, without which all of Java would fail to operate. It is therefore the default package that must be used with every program that will run Java, as it contains all of the logic necessary for exception handling, threads, classes that represent primitives (and their associated logic), and so on.
What is the use of interfaces extension through inheritance?
Interfaces are extremely useful in creating inheritance hierarchies in java programs. Interfaces cannot be extended but they will be implemented. Ex: public Interface Interface1 { public String getName() {}; } public Interface Interface2 { public int getAge() {}; } public class InterfaceExample implements Interface1, Interface2 { public String getName() { return "Anand"; } public int getAge() { return 28; } } Here I have implemented two interfaces in a class. I must provide implementation for all the methods that are declared inside both interfaces. So for simplicity I have just written 1 method in each interface but in practical situations you may have numerous methods inside each interface.
What is a predefined interface in java?
An interface is a collection of methods that must be implemented by the implementing class.An interface defines a contract regarding what a class must do, without saying anything about how the class will do it.Interface can contain declaration of methods and variables.implementing class must define all the methods declared in the interfaceIf a class implements an interface and does not implement all the methods then class itself must be declared as abstractVariables in interface automatically become static and final variableof the implementing classMembers of interface are implicitly public, so need not be declared as public.An interface must be implemented in class.
What does the native keyword do in Java?
The native keyword is used to tell Java that the method you are defining is actually implemented in machine-specific compiled code outside of Java. It is mainly used to import existing libraries of code compiled in C into Java, but is also used for the "low level" stuff which must be written specifically for each platform. If you try to look through the Java source code for how things like Sockets or the Math class are implemented, you will soon run into native methods. See the related link below for a well written example of how to use native methods yourself.
Explain the concept of interfaces in java with a suitable example for the same?
interface works like an abstract class it has methods which are not defined its job is to give a general idea about the class(generic) the class can have its own functions but interface makes java program to include all the functions or methods present in the interface there are ibuilt interfaces like runnable example in threads it is runnable it makes compulsory to the class to include all the methods in interface if you dont want that then use abstract key word before class eg: interface a{void meth(int i);} class one implements a{ void meth(int i) System.out.print(i); //all other members of class// if dont use meth function it will give an error for big projects certain general functions are necessary which have to be there everywhere it gives general idea of what the program is doing
