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What is functional interface in java?


Answer:

In Java, a Marker interface is an interface without any methods or fields declaration, means it is an empty interface. Similarly, a Functional Interface is an interface with just one abstract method declared in it. Runnable interface is an example of a Functional Interface. It has only run() method declared in it.

Lambda expression works on functional interfaces to replace anonymous classes.

@FunctionalInterface is a new annotation added in Java 8 to indicate that an interface declaration is intended to be a functional interface as defined by the Java Language Specification. @FunctionalInterface can be used for compiler level errors when the interface you have annotated is not a valid Functional Interface.

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List Of Java Interview Questions:

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  4. What is functional interface in java?
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  52. List Java-8 Streams terminal operations.
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Knowledge Centre
What is race condition?
A race condition is a situation in which two or more threads or processes are reading or writing some shared data, and the final result depends on the timing of how the threads are scheduled. Race conditions can lead to unpredictable results and subtle program bugs. A thread can prevent this from happening by locking an object. When an object is locked by one thread and another thread tries to call a synchronized method on the same object, the second thread will block until the object is unlocked.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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