Java Interview Questions and Answers

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Java Interview Questions and Answers

Hello, Looking for Java Interview Questions and Answers ? So you have found a correct place. In this article we have provided the mostly asked questions for Java language. Candidates going for the interviews can make the most use of this article to prepare themselves for the Java interview questions. Kindly go through the article below and checkout for Java interview questions and answers. For any questions or queries kindly ask below in comments.

Java Interview Questions and Answers

Java Interview Questions and Answers\

Java Interview Questions and Answers


What do you know about Java?
Java is a high-level programming language originally developed by Sun Micro systems and released in 1995. Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX.

What are the supported platforms by Java Programming Language?
Java runs on a variety of platforms, such as Windows, Mac OS, and the various versions of UNIX/Linux like HP-Unix, Sun Solaris, Redhat Linux, Ubuntu, CentOS, etc.
List any five features of Java?
Some features include Object Oriented, Platform Independent, Robust, Interpreted, Multi-threaded
Why is Java Architectural Neutral?
It’s compiler generates an architecture-neutral object file format, which makes the compiled code to be executable on many processors, with the presence of Java runtime system.
How Java enabled High Performance?
Java uses Just-In-Time compiler to enable high performance. Just-In-Time compiler is a program that turns Java bytecode, which is a program that contains instructions that must be interpreted into instructions that can be sent directly to the processor.
Why Java is considered dynamic?
It is designed to adapt to an evolving environment. Java programs can carry extensive amount of run-time information that can be used to verify and resolve accesses to objects on run-time.

What is Java Virtual Machine and how it is considered in context of Java’s platform independent feature?
When Java is compiled, it is not compiled into platform specific machine, rather into platform independent byte code. This byte code is distributed over the web and interpreted by virtual Machine (JVM) on whichever platform it is being run.
List two Java IDE’s?
Netbeans, Eclipse, etc.
List some Java keywords(unlike C, C++ keywords)?
Some Java keywords are import, super, finally, etc.
What do you mean by Object?
Object is a runtime entity and it’s state is stored in fields and behavior is shown via methods. Methods operate on an object's internal state and serve as the primary mechanism for object-to-object communication.
Define class?
A class is a blue print from which individual objects are created. A class can contain fields and methods to describe the behavior of an object.

What kind of variables a class can consist of?
A class consist of Local variable, instance variables and class variables.

What is a Local Variable?
Variables defined inside methods, constructors or blocks are called local variables. The variable will be declared and initialized within the method and it will be destroyed when the method has completed.

What is a Instance Variable?
Instance variables are variables within a class but outside any method. These variables are instantiated when the class is loaded.

What is a Class Variable?
These are variables declared with in a class, outside any method, with the static keyword.

What is Singleton class?
Singleton class control object creation, limiting the number to one but allowing the flexibility to create more objects if the situation changes.

What do you mean by Constructor?
Constructor gets invoked when a new object is created. Every class has a constructor. If we do not explicitly write a constructor for a class the java compiler builds a default constructor for that class.

List the three steps for creating an Object for a class?
An Object is first declared, then instantiated and then it is initialized.

What is the default value of byte datatype in Java?
Default value of byte datatype is 0.

What is the default value of float and double datatype in Java?
Default value of float and double datatype in different as compared to C/C++. For float its 0.0f and for double it’s 0.0d.

What do you mean by Access Modifier?
Java provides access modifiers to set access levels for classes, variables, methods and constructors. A member has package or default accessibility when no accessibility modifier is specified.

What is protected access modifier?
Variables, methods and constructors which are declared protected in a superclass can be accessed only by the subclasses in other package or any class within the package of the protected members' class.

What do you mean by synchronized Non Access Modifier?
Java provides these modifiers for providing functionalities other than Access Modifiers, synchronized used to indicate that a method can be accessed by only one thread at a time.

According to Java Operator precedence, which operator is considered to be with highest precedence?
Postfix operators i.e () [] . is at the highest precedence.

Variables used in a switch statement can be used with which datatypes?
Variables used in a switch statement can only be a byte, short, int, or char.

When parseInt() method can be used?
This method is used to get the primitive data type of a certain String.

Why is String class considered immutable?
The String class is immutable, so that once it is created a String object cannot be changed. Since String is immutable it can safely be shared between many threads ,which is considered very important for multithreaded programming.

Why is StringBuffer called mutable?
The String class is considered as immutable, so that once it is created a String object cannot be changed. If there is a necessity to make alot of modifications to Strings of characters then StringBuffer should be used.

What is the difference between StringBuffer and StringBuilder class?
Use StringBuilder whenever possible because it is faster than StringBuffer. But, if thread safety is necessary then use StringBuffer objects.

Which package is used for pattern matching with regular expressions?
java.util.regex package is used for this purpose.

java.util.regex consists of which classes?
java.util.regex consists of three classes − Pattern class, Matcher class and PatternSyntaxException class.

What is finalize() method?
It is possible to define a method that will be called just before an object's final destruction by the garbage collector. This method is called finalize( ), and it can be used to ensure that an object terminates cleanly.

What is an Exception?
An exception is a problem that arises during the execution of a program. Exceptions are caught by handlers positioned along the thread's method invocation stack.

What do you mean by Checked Exceptions?
It is an exception that is typically a user error or a problem that cannot be foreseen by the programmer. For example, if a file is to be opened, but the file cannot be found, an exception occurs. These exceptions cannot simply be ignored at the time of compilation.

Explain Runtime Exceptions?
It is an exception that occurs that probably could have been avoided by the programmer. As opposed to checked exceptions, runtime exceptions are ignored at the time of compliation.

Which are the two subclasses under Exception class?
The Exception class has two main subclasses : IOException class and RuntimeException Class.

When throws keyword is used?
If a method does not handle a checked exception, the method must declare it using the throwskeyword. The throws keyword appears at the end of a method's signature.

When throw keyword is used?
An exception can be thrown, either a newly instantiated one or an exception that you just caught, by using throw keyword.

How finally used under Exception Handling?
The finally keyword is used to create a block of code that follows a try block. A finally block of code always executes, whether or not an exception has occurred.

What things should be kept in mind while creating your own exceptions in Java?
While creating your own exception −

All exceptions must be a child of Throwable.

If you want to write a checked exception that is automatically enforced by the Handle or Declare Rule, you need to extend the Exception class.

You want to write a runtime exception, you need to extend the RuntimeException class.

Define Inheritance?
It is the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order.

When super keyword is used?
If the method overrides one of its superclass's methods, overridden method can be invoked through the use of the keyword super. It can be also used to refer to a hidden field.

What is Polymorphism?
Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.

What is Abstraction?
It refers to the ability to make a class abstract in OOP. It helps to reduce the complexity and also improves the maintainability of the system.

What is Abstract class?
These classes cannot be instantiated and are either partially implemented or not at all implemented. This class contains one or more abstract methods which are simply method declarations without a body.

When Abstract methods are used?
If you want a class to contain a particular method but you want the actual implementation of that method to be determined by child classes, you can declare the method in the parent class as abstract.
What is Encapsulation?
It is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. Therefore encapsulation is also referred to as data hiding.
What is the primary benefit of Encapsulation?
The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this Encapsulation gives maintainability, flexibility and extensibility to our code.
What is an Interface?
An interface is a collection of abstract methods. A class implements an interface, thereby inheriting the abstract methods of the interface.
Give some features of Interface?
It includes −
  • Interface cannot be instantiated
  • An interface does not contain any constructors.
  • All of the methods in an interface are abstract.
Define Packages in Java?
A Package can be defined as a grouping of related types(classes, interfaces, enumerations and annotations ) providing access protection and name space management.
Why Packages are used?
Packages are used in Java in-order to prevent naming conflicts, to control access, to make searching/locating and usage of classes, interfaces, enumerations and annotations, etc., easier.
What do you mean by Multithreaded program?
A multithreaded program contains two or more parts that can run concurrently. Each part of such a program is called a thread, and each thread defines a separate path of execution.
What are the two ways in which Thread can be created?
Thread can be created by: implementing Runnable interface, extending the Thread class.
What is an applet?
An applet is a Java program that runs in a Web browser. An applet can be a fully functional Java application because it has the entire Java API at its disposal.
An applet extend which class?
An applet extends java.applet.Applet class.
Explain garbage collection in Java?
It uses garbage collection to free the memory. By cleaning those objects that is no longer reference by any of the program.
Define immutable object?
An immutable object can’t be changed once it is created.
Explain the usage of this() with constructors?
It is used with variables or methods and used to call constructer of same class.
Explain Set Interface?
It is a collection of element which cannot contain duplicate elements. The Set interface contains only methods inherited from Collection and adds the restriction that duplicate elements are prohibited.
Explain TreeSet?
It is a Set implemented when we want elements in a sorted order.
What is Comparable Interface?
It is used to sort collections and arrays of objects using the collections.sort() and java.utils. The objects of the class implementing the Comparable interface can be ordered.
Difference between throw and throws?
It includes:

Throw is used to trigger an exception where as throws is used in declaration of exception.

Without throws, Checked exception cannot be handled where as checked exception can be propagated with throws.
Explain the following line used under Java Program −public static void main (String args[ ])
The following shows the explanation individually −
  • public − it is the access specifier.
  • static − it allows main() to be called without instantiating a particular instance of a class.
  • void − it affirns the compiler that no value is returned by main().
  • main() − this method is called at the beginning of a Java program.
  • String args[ ] − args parameter is an instance array of class String
Define JRE i.e. Java Runtime Environment?
Java Runtime Environment is an implementation of the Java Virtual Machine which executes Java programs. It provides the minimum requirements for executing a Java application;
What is JAR file?
JAR files is Java Archive fles and it aggregates many files into one. It holds Java classes in a library. JAR files are built on ZIP file format and have .jar file extension.
What is a WAR file?
This is Web Archive File and used to store XML, java classes, and JavaServer pages. which is used to distribute a collection of JavaServer Pages, Java Servlets, Java classes, XML files, static Web pages etc.
Define JIT compiler?
It improves the runtime performance of computer programs based on bytecode.
What is the difference between object oriented programming language and object based programming language?
Object based programming languages follow all the features of OOPs except Inheritance. JavaScript is an example of object based programming languages.
What is the purpose of default constructor?
The java compiler creates a default constructor only if there is no constructor in the class.
Can a constructor be made final?
No, this is not possible.
What is static block?
It is used to initialize the static data member, It is excuted before main method at the time of classloading.
Define composition?
Holding the reference of the other class within some other class is known as composition.
What is function overloading?
If a class has multiple functions by same name but different parameters, it is known as Method Overloading.
What is function overriding?
If a subclass provides a specific implementation of a method that is already provided by its parent class, it is known as Method Overriding.
Difference between Overloading and Overriding?
Method overloading increases the readability of the program. Method overriding provides the specific implementation of the method that is already provided by its super class parameter must be different in case of overloading, parameter must be same in case of overriding.
What is final class?
Final classes are created so the methods implemented by that class cannot be overridden. It can’t be inherited.
What is NullPointerException?
A NullPointerException is thrown when calling the instance method of a null object, accessing or modifying the field of a null object etc.

What are the ways in which a thread can enter the waiting state?
A thread can enter the waiting state by invoking its sleep() method, by blocking on IO, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its (deprecated) suspend() method.
How does multi-threading take place on a computer with a single CPU?
The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.
What invokes a thread's run() method?
After a thread is started, via its start() method of the Thread class, the JVM invokes the thread's run() method when the thread is initially executed.
Does it matter in what order catch statements for FileNotFoundException and IOException are written?
Yes, it does. The FileNoFoundException is inherited from the IOException. Exception's subclasses have to be caught first.
What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state.
Why Vector class is used?
The Vector class provides the capability to implement a growable array of objects. Vector proves to be very useful if you don't know the size of the array in advance, or you just need one that can change sizes over the lifetime of a program.
How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns.
What do you mean by Access Modifier?
Java provides access modifiers to set access levels for classes, variables, methods and constructors. A member has package or default accessibility when no accessibility modifier is specified.

What is protected access modifier?
Variables, methods and constructors which are declared protected in a superclass can be accessed only by the subclasses in other package or any class within the package of the protected members' class.

What do you mean by synchronized Non Access Modifier?
Java provides these modifiers for providing functionalities other than Access Modifiers, synchronized used to indicate that a method can be accessed by only one thread at a time.

According to Java Operator precedence, which operator is considered to be with highest precedence?
Postfix operators i.e () [] . is at the highest precedence.
Variables used in a switch statement can be used with which datatypes?
Variables used in a switch statement can only be a byte, short, int, or char.
When parseInt() method can be used?
This method is used to get the primitive data type of a certain String.
Why is String class considered immutable?
The String class is immutable, so that once it is created a String object cannot be changed. Since String is immutable it can safely be shared between many threads ,which is considered very important for multithreaded programming.
Why is StringBuffer called mutable?
The String class is considered as immutable, so that once it is created a String object cannot be changed. If there is a necessity to make alot of modifications to Strings of characters then StringBuffer should be used.
What is the difference between StringBuffer and StringBuilder class?
Use StringBuilder whenever possible because it is faster than StringBuffer. But, if thread safety is necessary then use StringBuffer objects.
Which package is used for pattern matching with regular expressions?
java.util.regex package is used for this purpose.
java.util.regex consists of which classes?
java.util.regex consists of three classes − Pattern class, Matcher class and PatternSyntaxException class.
What is finalize() method?
It is possible to define a method that will be called just before an object's final destruction by the garbage collector. This method is called finalize( ), and it can be used to ensure that an object terminates cleanly.
What is an Exception?
An exception is a problem that arises during the execution of a program. Exceptions are caught by handlers positioned along the thread's method invocation stack.
What do you mean by Checked Exceptions?
It is an exception that is typically a user error or a problem that cannot be foreseen by the programmer. For example, if a file is to be opened, but the file cannot be found, an exception occurs. These exceptions cannot simply be ignored at the time of compilation.
Explain Runtime Exceptions?
It is an exception that occurs that probably could have been avoided by the programmer. As opposed to checked exceptions, runtime exceptions are ignored at the time of compliation.
Which are the two subclasses under Exception class?
The Exception class has two main subclasses : IOException class and RuntimeException Class.
When throws keyword is used?
If a method does not handle a checked exception, the method must declare it using the throwskeyword. The throws keyword appears at the end of a method's signature.
When throw keyword is used?
An exception can be thrown, either a newly instantiated one or an exception that you just caught, by using throw keyword.

How finally used under Exception Handling?
The finally keyword is used to create a block of code that follows a try block. A finally block of code always executes, whether or not an exception has occurred.
What things should be kept in mind while creating your own exceptions in Java?
While creating your own exception −

All exceptions must be a child of Throwable.

If you want to write a checked exception that is automatically enforced by the Handle or Declare Rule, you need to extend the Exception class.

You want to write a runtime exception, you need to extend the RuntimeException class.
Define Inheritance?
It is the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order.
When super keyword is used?
If the method overrides one of its superclass's methods, overridden method can be invoked through the use of the keyword super. It can be also used to refer to a hidden field.
What is Polymorphism?
Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object.
What is Abstraction?
It refers to the ability to make a class abstract in OOP. It helps to reduce the complexity and also improves the maintainability of the system.
What is Abstract class?
These classes cannot be instantiated and are either partially implemented or not at all implemented. This class contains one or more abstract methods which are simply method declarations without a body.
When Abstract methods are used?
If you want a class to contain a particular method but you want the actual implementation of that method to be determined by child classes, you can declare the method in the parent class as abstract.
What is Encapsulation?
It is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. Therefore encapsulation is also referred to as data hiding.
What is the primary benefit of Encapsulation?
The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this Encapsulation gives maintainability, flexibility and extensibility to our code.
What is an Interface?
An interface is a collection of abstract methods. A class implements an interface, thereby inheriting the abstract methods of the interface.
Give some features of Interface?
It includes −

Interface cannot be instantiated

An interface does not contain any constructors.

All of the methods in an interface are abstract.
Define Packages in Java?
A Package can be defined as a grouping of related types(classes, interfaces, enumerations and annotations ) providing access protection and name space management.
Why Packages are used?
Packages are used in Java in-order to prevent naming conflicts, to control access, to make searching/locating and usage of classes, interfaces, enumerations and annotations, etc., easier.
What do you mean by Multithreaded program?
A multithreaded program contains two or more parts that can run concurrently. Each part of such a program is called a thread, and each thread defines a separate path of execution.
What are the two ways in which Thread can be created?
Thread can be created by: implementing Runnable interface, extending the Thread class.
What is an applet?
An applet is a Java program that runs in a Web browser. An applet can be a fully functional Java application because it has the entire Java API at its disposal.
An applet extend which class?
An applet extends java.applet.Applet class.
Explain garbage collection in Java?
It uses garbage collection to free the memory. By cleaning those objects that is no longer reference by any of the program.
Define immutable object?
An immutable object can’t be changed once it is created.
Explain the usage of this() with constructors?
It is used with variables or methods and used to call constructer of same class.
Explain Set Interface?
It is a collection of element which cannot contain duplicate elements. The Set interface contains only methods inherited from Collection and adds the restriction that duplicate elements are prohibited.
Explain TreeSet?
It is a Set implemented when we want elements in a sorted order.
What is Comparable Interface?
It is used to sort collections and arrays of objects using the collections.sort() and java.utils. The objects of the class implementing the Comparable interface can be ordered.
Difference between throw and throws?
It includes:

Throw is used to trigger an exception where as throws is used in declaration of exception.

Without throws, Checked exception cannot be handled where as checked exception can be propagated with throws.
Explain the following line used under Java Program −public static void main (String args[ ])
The following shows the explanation individually −
  • public − it is the access specifier.
  • static − it allows main() to be called without instantiating a particular instance of a class.
  • void − it affirns the compiler that no value is returned by main().
  • main() − this method is called at the beginning of a Java program.
  • String args[ ] − args parameter is an instance array of class String
Define JRE i.e. Java Runtime Environment?
Java Runtime Environment is an implementation of the Java Virtual Machine which executes Java programs. It provides the minimum requirements for executing a Java application;
What is JAR file?
JAR files is Java Archive fles and it aggregates many files into one. It holds Java classes in a library. JAR files are built on ZIP file format and have .jar file extension.
What is a WAR file?
This is Web Archive File and used to store XML, java classes, and JavaServer pages. which is used to distribute a collection of JavaServer Pages, Java Servlets, Java classes, XML files, static Web pages etc.
Define JIT compiler?
It improves the runtime performance of computer programs based on bytecode.
What is the difference between object oriented programming language and object based programming language?
Object based programming languages follow all the features of OOPs except Inheritance. JavaScript is an example of object based programming languages.
What is the purpose of default constructor?
The java compiler creates a default constructor only if there is no constructor in the class.
Can a constructor be made final?
No, this is not possible.
What is static block?
It is used to initialize the static data member, It is excuted before main method at the time of classloading.
Define composition?
Holding the reference of the other class within some other class is known as composition.
What is function overloading?
If a class has multiple functions by same name but different parameters, it is known as Method Overloading.
What is function overriding?
If a subclass provides a specific implementation of a method that is already provided by its parent class, it is known as Method Overriding.
Difference between Overloading and Overriding?
Method overloading increases the readability of the program. Method overriding provides the specific implementation of the method that is already provided by its super class parameter must be different in case of overloading, parameter must be same in case of overriding.
What is final class?
Final classes are created so the methods implemented by that class cannot be overridden. It can’t be inherited.
What is NullPointerException?
A NullPointerException is thrown when calling the instance method of a null object, accessing or modifying the field of a null object etc.
What are the ways in which a thread can enter the waiting state?
A thread can enter the waiting state by invoking its sleep() method, by blocking on IO, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its (deprecated) suspend() method.
How does multi-threading take place on a computer with a single CPU?
The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.
What invokes a thread's run() method?
After a thread is started, via its start() method of the Thread class, the JVM invokes the thread's run() method when the thread is initially executed.

Does it matter in what order catch statements for FileNotFoundException and IOException are written?
Yes, it does. The FileNoFoundException is inherited from the IOException. Exception's subclasses have to be caught first.

What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state.

Why Vector class is used?
The Vector class provides the capability to implement a growable array of objects. Vector proves to be very useful if you don't know the size of the array in advance, or you just need one that can change sizes over the lifetime of a program.

How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns.
What are the restriction imposed on a static method or a static block of code?
A static method should not refer to instance variables without creating an instance and cannot use "this" operator to refer the instance.
Can an Interface extend another Interface?
Yes an Interface can inherit another Interface, for that matter an Interface can extend more than one Interface.
Which object oriented Concept is achieved by using overloading and overriding?
Polymorphism
What is an object's lock and which object's have locks?
An object's lock is a mechanism that is used by multiple threads to obtain synchronized access to the object. A thread may execute a synchronized method of an object only after it has acquired the object's lock.

What is Downcasting?
It is the casting from a general to a more specific type, i.e. casting down the hierarchy.

What are order of precedence and associativity and how are they used?
Order of precedence determines the order in which operators are evaluated in expressions. Associatity determines whether an expression is evaluated left-to-right or right-to-left.

If a method is declared as protected, where may the method be accessed?
A protected method may only be accessed by classes or interfaces of the same package or by subclasses of the class in which it is declared.

What is the difference between inner class and nested class?
When a class is defined within a scope of another class, then it becomes inner class. If the access modifier of the inner class is static, then it becomes nested class.

What restrictions are placed on method overriding?
Overridden methods must have the same name, argument list, and return type. The overriding method may not limit the access of the method it overrides.

What is constructor chaining and how is it achieved in Java?
A child object constructor always first needs to construct its parent. In Java it is done via an implicit call to the no-args constructor as the first statement.

Can a double value be cast to a byte?
Yes, a double value can be cast to a byte.

How does a try statement determine which catch clause should be used to handle an exception?
When an exception is thrown within the body of a try statement, the catch clauses of the try statement are examined in the order in which they appear. The first catch clause that is capable of handling the exception is executed. The remaining catch clauses are ignored.

Is it better to synchronize critical section of getInstance() method or whole getInstance() method ?
Answer is critical section because if we lock whole method than every time some one call this method will have to wait even though we are not creating any object)

 What is the difference when String is gets created using literal or new() operator ?
When we create string with new() its created in heap and not added into string pool while String created using literal are created in String pool itself which exists in Perm area of heap.

Does not overriding hashcode() method has any performance implication ?
This is a good question and open to all , as per my knowledge a poor hashcode function will result in frequent collision in HashMap which eventually increase time for adding an object into Hash Map.

What’s wrong using HashMap in multithreaded environment? When get() method go to infinite loop ?
Another good question. His answer was during concurrent access and re-sizing.

  What do you understand by thread-safety ? Why is it required ? And finally, how to achieve thread-safety in Java Applications ? 
Java Memory Model defines the legal interaction of threads with the memory in a real computer system. In a way, it describes what behaviors are legal in multi-threaded code. It determines when a Thread can reliably see writes to variables made by other threads. It defines semantics for volatile, final & synchronized, that makes guarantee of visibility of memory operations across the Threads.

So this was all about Java Interview Questions and Answers. Hope you liked our article. Candidates start preparing for the Java interview questions and answers for your interviews. This are the questions mostly asked in the interviews this article would surely help you a lot.  Feel free to ask questions below in comments regarding Java Interview Questions and Answers.


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