Java Interview Questions

a) void f() throws ioexception Bcoz the overriding method must NOT throw checked exceptions that are new or broader than those declared by the overridden method. For example, a method that declares a...

There is no methods in serializable interface. It is a marker interface and null interface.

Does not have any methods in Serializable interface......

class.forName("full qualm name"); is used to load the driver explicitly and DriverManger.registerDriver(new classname()); will implicitly loads the driver automatically

class.forName() is a method ,this method takes a string representing a fully qualified class name(one that includes the package name) and loads the corresponding class.

what is object class in java?

the locale class to used to tailor program output to the conventions of a particular geographic, political, or cultural region

CompareTo method which is present in the String class is used to check the two strings. It checks each character with the other String and if found equals then returns 0. Else negative value or positi...

CompareTo() method is derived from Comparable interface and is used to find the Ordering of Strings.
equals() method is from java.lang.Object and used for comparing objects.

Preemptive scheduling enables the highest priority task execution until waiting or dead states entered. It also executes, until a higher priority task enters. Time slicing allows a task to execute fo...

preemptive Scheduling:- the highest priority thread executes First that means when one thread is in running state that time the highest priority interrupt enters then this interrupt will executes firs...

Adding couple of other differences between Set and Map:
1. You can have an iterator for a set but not a map.
2. Processing a complete map takes longer whereas processing a complete set takes a comparatively less time (reason - iterator)

A Set is a collection that has no duplicate elements.  
A List is a collection that has an order assoicated with its elements.  
A map is a way of storing key/value pairs. The way of storing a Map is similar to two-column table.

STATIC VARIABLE

1)outclass is called static variable

2)static variable access member of its enclosing class through on object.

NON-STATIC VARIABLE

1)inner class is called non-static variable
2)nested class and it has access to all of the variable and methods object of its earlier.

Static variable: 1)Memory allocated before creation of object. 2)static variables are class variables and the values remains same fr the whole class and its value is same for all classes in a program...

yes it is possible.using finalize in garbage collection

No, an unreachable object cannot be reached again.

ArrayList , Vector default size is 10. vector increment is 10 and array list is 10/2

Instead of 30 it would give 40.

1.The compiler does not initialize auto and register variables at the beginning of a switch body where as we can put data definitions at the beginning of the switch body.
2.We cannot use a switch statement to jump over initializations.

Whenever the window needs to be refreshed the paint() method is called automatically.The user does not specify the paint(). The user specifies the repaint() in order to obtain a rendering.repaint() i...

The run() method must be implemented by all the threads.

We can access a public class out of its package where as the access outside the package is not possible with a non public class.

To read from one stream and then to write on other stream we use i/o filter.

The finally clause of a try-catch-finally statement executed when the thread of execution terminates or an exception occurs within the execution of the finally clause.

Any checked exceptions that are not caught within the body of the method must declare in a methods throws clause.

The Collection interface is used to pass around collections of objects where maximum generality is desired.It is one of the root interfaces of the Java collection classes.It provides support for the implementation of an unordered collection of objects that may contain duplicates.

Clipping regions are set to the repinted window on the area that requires repainting.When a window is repainted by the AWT painting thread, it sets the clipping regions tothe area of the window that requires repainting.

Jar files are important as it contains the class, image, and sound files for a Java application or applet gathered into a single file and possibly compressed. When a programmer gets a Java program dev...