The Private modifier restricts the access of members from outside the class. A class and interface cannot be public. The Public access modifier can be associated with class, method, constructor, interface, etc.
The protected access modifier can be associated with 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.
The default access modifier does not have keyword a variable or method declared without any access control modifier is available to any other class in the same package. Explain different way of using thread? What are pass by reference and passby value? What is HashMap and Map? Difference between HashMap and HashTable? Difference between Vector and ArrayList?
Difference between Swing and Awt? What is the difference between a constructor and a method? What is an Iterator? State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships on declared items qualified by these modifiers. What is an abstract class? What is static in java? What is final? What if the static modifier is removed from the signature of the main method?
What if I write static public void instead of public static void? What if I do not provide the String array as the argument to the method? What is the first argument of the String array in main method? If I do not provide any arguments on the command line, then the String array of Main method will be empty or null? How can one prove that the array is not null but empty using one line of code?
What environment variables do I need to set on my machine in order to be able to run Java programs? Can an application have multiple classes having main method? Can I have multiple main methods in the same class? Do I need to import java. Will the JVM load the package twice at runtime? What are Checked and UnChecked Exception? What is Overriding?
What are different types of inner classes? Are the imports checked for validity at compile time? ABCD compile? Does importing a package imports the subpackages as well? Does importing com. What is the difference between declaring a variable and defining a variable? What is the default value of an object reference declared as an instance variable? Can a top level class be private or protected? What type of parameter passing does Java support?
Primitive data types are passed by reference or pass by value? Objects are passed by value or by reference? What is serialization? How do I serialize an object to a file? Which methods of Serializable interface should I implement? How can I customize the seralization process?
What is the common usage of serialization? What is Externalizable interface? When you serialize an object, what happens to the object references included in the object? What one should take care of while serializing the object? What happens to the static fields of a class during serialization? Does Java provide any construct to find out the size of an object? Give a simplest way to find out the time a method takes for execution without using any profiling tool?
What are wrapper classes? Why do we need wrapper classes? What are checked exceptions? What are runtime exceptions? What is the difference between error and an exception?
How to create custom exceptions? If I want an object of my class to be thrown as an exception object, what should I do? If my class already extends from some other class what should I do if I want an instance of my class to be thrown as an exception object?
How does an exception permeate through the code? What are the different ways to handle exceptions? What is the basic difference between the 2 approaches to exception handling.
When should you use which approach? Is it necessary that each try block must be followed by a catch block? If I write return at the end of the try block, will the finally block still execute? If I write System. How are Observer and Observable used? How does Java handle integer overflows and underflows? Does garbage collection guarantee that a program will not run out of memory? What is the difference between preemptive scheduling and time slicing?
When a thread is created and started, what is its initial state? It means JVM first goes to static block even before it looks for the main method in the program.
We observe that JVM first executes the static block, if it is present in the program. After that it searches for the main method. If the main method is not found, it gives error. There should be exactly three dots between String and array; otherwise, it gives an error. We can define any number of main method in the class, but the method signature must be different.
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