Can we declare the main method of our class as private?
Ans: In java, main method must be public static in order to run any application correctly. If main method is declared as private, developer won’t get any compilation error however, it will not get executed and will give a runtime error.
How can we pass argument to a function by reference instead of pass by value?
Ans: In java, we can pass argument to a function only by value and not by reference.
How an object is serialized in java?
Ans: In java, to convert an object into byte stream by serialization, an interface with the name Serializable is implemented by the class. All objects of a class implementing serializable interface get serialized and their state is saved in byte stream.
When we should use serialization?
Ans: Serialization is used when data needs to be transmitted over the network. Using serialization, object’s state is saved and converted into byte stream .The byte stream is transferred over the network and the object is re-created at destination.
Is it compulsory for a Try Block to be followed by a Catch Block in Java for Exception handling?
Ans: Try block needs to be followed by either Catch block or Finally block or both. Any exception thrown from try block needs to be either caught in the catch block or else any specific tasks to be performed before code abortion are put in the Finally block.
What’s the difference between an array and Vector?
Ans: An array groups data of same primitive type and is static in nature while vectors are dynamic in nature and can hold data of different data types.
What is multi-threading?
Ans: Multi threading is a programming concept to run multiple tasks in a concurrent manner within a single program. Threads share same process stack and running in parallel. It helps in performance improvement of any program.
Why Runnable Interface is used in Java?
Ans: Runnable interface is used in java for implementing multi threaded applications. Java.Lang.Runnable interface is implemented by a class to support multi threading.
What are the two ways of implementing multi-threading in Java?
Ans: Multi threaded applications can be developed in Java by using any of the following two methodologies:
1. By using Java.Lang.Runnable Interface. Classes implement this interface to enable multi threading. There is a Run() method in this interface which is implemented.
2. By writing a class that extend Java.Lang.Thread class.
When a lot of changes are required in data, which one should be a preference to be used? String or StringBuffer?
Ans: Since String Buffers are dynamic in nature and we can change the values of StringBuffer objects unlike String which is immutable, it’s always a good choice to use StringBuffer when data is being changed too much. If we use String in such a case, for every data change a new String object will be created which will be an extra overhead.
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Ans: In java, main method must be public static in order to run any application correctly. If main method is declared as private, developer won’t get any compilation error however, it will not get executed and will give a runtime error.
How can we pass argument to a function by reference instead of pass by value?
Ans: In java, we can pass argument to a function only by value and not by reference.
How an object is serialized in java?
Ans: In java, to convert an object into byte stream by serialization, an interface with the name Serializable is implemented by the class. All objects of a class implementing serializable interface get serialized and their state is saved in byte stream.
When we should use serialization?
Ans: Serialization is used when data needs to be transmitted over the network. Using serialization, object’s state is saved and converted into byte stream .The byte stream is transferred over the network and the object is re-created at destination.
Is it compulsory for a Try Block to be followed by a Catch Block in Java for Exception handling?
Ans: Try block needs to be followed by either Catch block or Finally block or both. Any exception thrown from try block needs to be either caught in the catch block or else any specific tasks to be performed before code abortion are put in the Finally block.
What’s the difference between an array and Vector?
Ans: An array groups data of same primitive type and is static in nature while vectors are dynamic in nature and can hold data of different data types.
What is multi-threading?
Ans: Multi threading is a programming concept to run multiple tasks in a concurrent manner within a single program. Threads share same process stack and running in parallel. It helps in performance improvement of any program.
Why Runnable Interface is used in Java?
Ans: Runnable interface is used in java for implementing multi threaded applications. Java.Lang.Runnable interface is implemented by a class to support multi threading.
What are the two ways of implementing multi-threading in Java?
Ans: Multi threaded applications can be developed in Java by using any of the following two methodologies:
1. By using Java.Lang.Runnable Interface. Classes implement this interface to enable multi threading. There is a Run() method in this interface which is implemented.
2. By writing a class that extend Java.Lang.Thread class.
When a lot of changes are required in data, which one should be a preference to be used? String or StringBuffer?
Ans: Since String Buffers are dynamic in nature and we can change the values of StringBuffer objects unlike String which is immutable, it’s always a good choice to use StringBuffer when data is being changed too much. If we use String in such a case, for every data change a new String object will be created which will be an extra overhead.