Remove duplicates from an array java

Posted by: Instanceofjava Posted date: 11:09 AM / comment : 0

Removing duplicate elements form an array using collections:

  1. package com.instanceofjavaTutorial;
  2.  
  3. import java.util.Arrays;
  4. import java.util.HashSet;
  5. import java.util.List;
  6. import java.util.Set;
  7.  
  8. public class RemoveDupArray {
  9.  
  10.   public static void main(String[] args) {
  11.  
  12.   // A string array with duplicate values
  13.    String[] data = { "E", "C", "B", "E", "A", "B", "E", "D", "B", "A" };
  14.  
  15. System.out.println("Original array         : " + Arrays.toString(data));
  16.  
  17.  List<String> list = Arrays.asList(data);
  18.  Set<String> set = new HashSet<String>(list);
  19.  
  20.   System.out.print("After removing duplicates: ");
  21.   String[] resarray= new String[set.size()];
  22.    set.toArray(resarray);
  23.  
  24.  for (String ele: resarray) {
  25.  
  26.  System.out.print(ele + ", ");
  27.  
  28.  }
  29.  
  30. }
  31.  
  32. }



  1. OutPut:
  2. Original array         : [E, C, B, E, A, B, E, D, B, A]
  3. After removing duplicates: D, E, A, B, C




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VarArgs in java

Posted by: Instanceofjava Posted date: 10:42 PM / comment : 1

  • The full form of var-arg is variable length arguments.
  • Till JDK 1.4 we must define overloaded methods to pass different list of arguments .
  • But using this feature we can define method to pass ZERO to 'n'  number of arguments.
  • Syntax: After data type we must place three dots.


  1.          void method(int... i){
  2.          }
  • Internally Var-arg is a single dimensional array. So we can also pass single dimensional array as argument.
  1. package instanceofjavaforus;
  2. public class VDemo{ 
  3.  void print(int... args){
  4. for(int i=0;i<args.length;i++){
  5. System.out.println(args[i]);
  6. }
  7. System.out.println();
  8. }
  9. public static void main(String args[]){
  10.  Vdemo obj= new Vdemo();
  11. int x={1,2};
  12. obj.print(x);// works fine
  13. obj.print(1,2,3,4);// works fine
  14. obj.print();// works fine
  15. //int... var=new int[5]; compile time error: not a valid statement
  16. } 
  17.  
  18. Output:
  19. 1
  20. 2

  22. 1
  23. 2
  24. 3
  25. 4

It must be last argument:

  1. package instanceofjavaforus;
  2. public class VDemo{ 
  3. void print(int x){
  4.  System.out.println("int x");
  5. }
  6.  
  7. void print(int x, int y){
  8.  System.out.println("int x, int y");
  9. } 
  10.  void print(int x, int y,int... args){
  11. System.out.println("int x, int y,int... args");
  12. }
  13. void print(int... args){
  14. System.out.println("int x, int y");
  15. }
  16.  public static void main(String args[]){
  17.  Vdemo obj= new Vdemo();
  18. int x={1,2};
  19. obj.print(1);
  20. obj.print(x);// works fine
  21. obj.print(1,2,3,4);// works fine
  22. obj.print();// works fine
  23. //int... var=new int[5]; compile time error: not a valid statement
  24. } 

  26. Output:
  27. int x
  28. int x, int y
  29. int x, int y,int... args
  • if we declared  placed any type after var-arg in the arguments list of a method then it throws a compile time error.

  1. void print(int x, int y, int...args, int z){// compile time error
  2. // throws Compile time error:The variable argument type int of the method print must be the
  3.  // last parameter
  4.  System.out.println("int x, int y");
  5. } 
  6.  void print(int x, int y,int... args){  // valid
  7. System.out.println("int x, int y,int... args");
  8. }
Overloading method with normal and varargs types :

  1. package instanceofjavaforus;
  2. public class VDemo{ 
  3.  void print(int... args){
  4. System.out.println("var arg method");
  5. }
  6. void print(int args){
  7. System.out.println("normal method");
  8. }
  9.  
  10. public static void main(String args[]){
  11.  Vdemo obj= new Vdemo();
  12. obj.print(1);// works fine
  13. } 
  14.  }
  15. Output:
  16. normal method

Overloading method with normal and varargs types in super and sub classes:

var args Program 1:

  1. package instanceofjavaforus;
  2. public class VDemo{ 
  3.  void print(int... args){
  4. System.out.println("super class method");
  5. }
  6. } 

  1. package instanceofjavaforus;
  2. public class Test extends VDemo{ 
  3.  void print(int args){
  4. System.out.println("sub class method");
  5. }
  6. public static void main(String args[]){
  7.  VDemo vobj= new VDemo();
  8. vobj.print(10);
  9. Test tobj= new Test();
  10. tobj.print(10);
  11. }
  12. }
  13. OutPut:
  14. Super class method
  15. Sub class method

var args Program 2:

  1. package instanceofjavaforus;
  2. public class VDemo{ 
  3.  void print(int args){
  4. System.out.println("super class method");
  5. }
  6. }



  1. package instanceofjavaforus;
  2.  
  3. public class Test extends VDemo{ 
  4.  
  5.  void print(int... args){
  6. System.out.println("sub class method");
  7. }
  8. public static void main(String args[]){
  9.  
  10.  VDemo vobj= new VDemo();
  11. vobj.print(10);
  12. Test tobj= new Test();
  13. tobj.print(10);
  14.  
  15. }
  16. }
  17. OutPut:
  18. Super class method
  19. Super class method

How to Convert string to date in java

Posted by: Instanceofjava Posted date: 5:11 PM / comment : 0


  • Whenever are having a requirement of converting string (date as string ) in to date we need to use SimpledateFormat class which is present in java.text package.
  • To convert string to date in java we need to follow two steps.
  • First we need to create SimpledateFormat class object by passing pattern of date which we want as a string.
  • Ex: SimpleDateFormat  formatter = new SimpleDateFormat("dd/MM/yyyy");
  • And next we need to call parse() method on the object of  SimpleDateFormat then it will returns Date object.
  • parse() method  throws ParseException so need to handle this exception.
  • By using format method of the object will get string format of given date
  • formatter.format(date).
  • How to convert java string to date object 
  • Java SimpleDateFormat String to Date conversion and parsing examples
Letter Date or Time Component Presentation Examples
G Era designator Text AD
y Year Year 2015; 15
Y Week year Year 2009; 09
M Month in year Month July; Jul;07
w Week in year Number 25
W Week in month Number 3
D Day in year Number 143
d Day in month Number 37
F Day of week in month Number 1
E Day name in week Text Tuesday; Tue
u Day number of week (1 = Monday, ..., 7 = Sunday) Number 1
a Am/pm marker Text PM
H Hour in day (0-23) Number 0
k Hour in day (1-24) Number 12
K Hour in am/pm (0-11) Number 0
h Hour in am/pm (1-12) Number 12
m Minute in hour Number 30
s Second in minute Number 30
S Millisecond Number 778
z Time zone General time zone Pacific Standard Time; PST; GMT-08:00
Z Time zone RFC 822 time zone -0800
X Time zone ISO 8601 time zone -08; -0800; -08:00
(Ref: Oracle DOCS)

Example program on SimpleDateFormat :

1. Convert string to date in java in MMM dd, yyyy format

Input : Jan 1, 2015 (MMM dd, yyyy):

  1. package com.instanceofjava;
  2.  
  3. public Class DateFormatDemo{ 
  4.  
  5. public static void main (String args[]) {
  6. SimpleDateFormat formatter = new SimpleDateFormat("MMM dd, yyyy");
  7. String dateInString = "Jan 1, 2015"; 
  8.  
  9. try{
  10.  
  11. Date date = formatter.parse(dateInString);
  12. System.out.println(date);
  13. System.out.println(formatter.format(date));  
  14.  
  15. }catch(ParseException e){
  16. e.printStackTrace();
  17. }
  18. }
  19. } 

  21. Output: 
  22. Thu Jan 01 00:00:00 IST 2015
  23. Jan 01, 2015




2.How to convert string into date format in java day MMM dd, yyyy format example

 Input : Sat, Feb 14 2015 (E, MMM dd yyyy):

  1. package com.instanceofjava;
  2.  
  3. public Class DateFormatDemo{ 
  4.  
  5. public static void main (String args[]) {
  6.  
  7. SimpleDateFormat formatter = new SimpleDateFormat("E, MMM dd yyyy");
  8. String dateInString = "Sat, February 14 2015"; 
  9.  
  10. try{
  11.  
  12. Date date = formatter.parse(dateInString);
  13. System.out.println(date);
  14. System.out.println(formatter.format(date));  
  15.  
  16. }catch(ParseException e){
  17. e.printStackTrace();
  18. }
  19. }
  20. }
  21. Output: 
  22. Sat Feb 14 00:00:00 IST 2015
  23. Sat, Feb 14 2015



3. Convert string to date in java in dd/MM/ yyyy format example program

Input : 01/01/2015 (dd/MM/yyyy):

  1. package com.instanceofjava;
  2.  
  3. public Class DateFormatDemo{ 
  4.  
  5. public static void main (String args[]) {
  6.  
  7. SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yyyy);
  8. String dateInString = "01/01/2015";
  9.  
  10. try{
  11.  
  12. Date date = formatter.parse(dateInString);
  13. System.out.println(date);
  14. System.out.println(formatter.format(date)); 
  15.  
  16. }catch(ParseException e){
  17. e.printStackTrace();
  18. }
  19. }
  20. } 

  22. Output: 
  23. Thu Jan 01 00:00:00 IST 2015
  24. 01/01/2015


4. Convert string to date in java in dd-MMM-yyyy format example program

Input : 1-Jan-2015 (dd-MMM-yyyy):

  1. package com.instanceofjava;
  2.  
  3. public Class DateFormatDemo{ 
  4.  
  5. public static void main (String args[]) {
  6. SimpleDateFormat formatter = new SimpleDateFormat("dd-MMM-yyyy");
  7. String dateInString = "1-Jan-2015"; 
  8.  
  9. try{
  10.  
  11. Date date = formatter.parse(dateInString);
  12. System.out.println(date);
  13. System.out.println(formatter.format(date));  
  14.  
  15. }catch(ParseException e){
  16. e.printStackTrace();
  17. }
  18. }
  19. } 

  21. Output: 
  22. Thu Jan 01 00:00:00 IST 2015
  23. 01-Jan-2015


  5. Convert string to date in java in yyyyMMdd format example program

Input : 20150101 (yyyyMMdd):

  1. package com.instanceofjava;
  2.  
  3. public Class DateFormatDemo{ 
  4.  
  5. public static void main (String args[]) {
  6.  
  7. SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd");
  8. String dateInString = "20150101"; 
  9.  
  10. try{
  11.  
  12. Date date = formatter.parse(dateInString);
  13. System.out.println(date);
  14. System.out.println(formatter.format(date));  
  15.  
  16. }catch(ParseException e){
  17. e.printStackTrace();
  18. }
  19. }
  20. } 

  22. Output: 
  23. Thu Jan 01 00:00:00 IST 2015
  24. 20150101


6.Convert string to date in java in ddMMyyyy format example program

Input : 01012015 (ddMMyyyy):

  1. package com.instanceofjava;
  2.  
  3. public Class DateFormatDemo{ 
  4.  
  5. public static void main (String args[]) {
  6.  
  7. SimpleDateFormat formatter = new SimpleDateFormat("ddMMyyyy");
  8. String dateInString = "01012015"; 
  9.  
  10. try{
  11.  
  12. Date date = formatter.parse(dateInString);
  13. System.out.println(date);
  14. System.out.println(formatter.format(date));  
  15.  
  16. }catch(ParseException e){
  17. e.printStackTrace();
  18. }
  19. }
  20. } 

  22. Output: 
  23. Thu Jan 01 00:00:00 IST 2015
  24. 01012015


7.Convert string to date in java in dd-MMM-yy format example program

Input : 01-January-15 (dd-MMM-yy):

  1. package com.instanceofjava;
  2.  
  3. public Class DateFormatDemo{ 
  4.  
  5. public static void main (String args[]) {
  6.  
  7. SimpleDateFormat formatter = new SimpleDateFormat("dd-MMMM-yy");
  8. String dateInString = "01-January-2015"; 
  9.  
  10. try{
  11.  
  12. Date date = formatter.parse(dateInString);
  13. System.out.println(date);
  14. System.out.println(formatter.format(date));  
  15.  
  16. }catch(ParseException e){
  17. e.printStackTrace();
  18. }
  19. }
  20. } 

  22. Output: 
  23. Thu Jan 01 00:00:00 IST 2015
  24. 01012015


8.Convert string to date in java in dd-M-yyyy HH:mm:SS format example program

 
convert string to date in java

JVM Architecture

Posted by: Instanceofjava Posted date: 3:30 PM / comment : 6

  • This topic clears your questions like Explain jvm architecture in java  , jvm architecture in java with diagram, how JVM works internally and areas of Java Virtual Machine.
  • Virtual machine : In general terms Virtual machine is a software that creates an environment between the computer and end user in which end user can operate programs.
  • As per functionality Virtual machine is creation of number of different identical execution environments on a single computer to execute programs is called Virtual machine.
  • Java Virtual machine: it is also Virtual machine that runs java bytecode  by creating five identical run time areas to execute class members.

Function of java virtual machine

  • The bytecode is generated by java compiler in a JVM understandable format.
  • As a programmer we develop a java application and when we compile a java program, the compiler will generate .class (dot class) file.
  • The .class file contains byte code (Special java instructions).
  • To execute a java program we take the help of JVM (java virtual machine) to the JVM we have to provide .class file as the input.

Types of JVMs:

  • The java 2 SDK , Standard Edition , contains two implementation of the java virtual machine 
  1. Java HotSpot Client VM
  2. Java Hotspot Server VM

Java HotSpot Client VM:

  • The Hotspot Client VM is the default virtual machine of the java 2 SDK and java 2 run time environment .
  • As its name implies, it is tuned for best performance when running applications in a client environment by reducing application start up time and memory footprint.  

Java HotSpot Server VM:

  • The java HotSpot server VM is designed for maximum program execution speed for applications running in a server environment.
  • The Java HotSpot Server VM is invoked by using the server command line option when an application , as in java server MyApp.
  • Some of the features java HotSpot technology , common to both VM implementations, are the following.

Adaptive compiler:

  • Applications are launched using a standard interpreter, but the code is then analyzed as it runes to detect performance bottlenecks, or "hot spots".
  • The Java HotSpot VMs compile those performance critical portions of the code for a boost in performance , while avoiding unnecessary compilation of seldom used code.
  • The Java HotSpot VMs also uses the adoptive compiler to decide on the fly , how best to optimize compiled code with techniques such as in lining.
  • The run time analysis performed by the compiler allows it to eliminate guesswork in determining which optimizations will yield the largest performance benefit.

Rapid memory allocation garbage collection:

  • Java HotSpot technology provides for rapid memory allocation for objects , and it has a fast, efficient, state-of-the-art  garbage collector. 

Thread Synchronization:

  • The Java programming language allows for use of multiple , concurrent paths of program execution (called threads).
  • Java HotSpot technology provides a thread- handling capability that is designed to scale readily for use in large , shared memory multiprocessor servers.

Jvm architecture in java with diagram





Class Loader Sub System:     

  • The class loader sub system will take a .class file as the input and performance the following operations. 
  • The class loader sub system is responsible for loading the .class file (Byte code) into the JVM.
  • Before loading the Byte code into the JVM it will verify where there the Byte code is valid      or   not. This verification will be done by Byte code verifier.
  • If the Byte code is valid then the memory for the Byte code will be allocated in different areas.
  • The different areas into which the Byte code is loaded are called as Run Time Data Areas. The various run time data areas are.


1.Method Area: 

  • Java Virtual Machine Method Area can be used for storing all the class code and method code.
  • All classes bytecode is loaded and stored in this run time area , and all static variables are created in this area.

2.Heap Memory:

  • JVM Heap Area can be used for storing all the objects that are created.
  • It is the main memory of JVM , all objects of classes :- non static variables memory are created in this run time area.
  • This runtime  area memory is finite memory.
  • This area can be configured at the time of setting up of runtime environment using non standard option like
  • java -xms <size> class-name.
  • This can be expandable by its own , depending on the object creation.
  • Method area and Heap area both are sharable memory areas.

3.Java Stack area:

  • JVM stack Area can be used for storing the information of the methods. That is under execution. The java stack can be considered as the combination of stack frames where every frame will contain the stat of a single method.
  • In this runtime area all Java methods are executed.
  • In this runtime JVM by default creates two threads. they are
  • 1.main method
  • 2.Garbage Collection Thread
  •  main thread responsible to execute java methods starts with main method.
  • Also responsible to create objects in heap area if its finds new keyword in any method logic.
  • Garbage collection thread is responsible to destroy all unused objects from heap area.

4.PC Register (program counter) area:

  • The PC Register i Java Virtual Machine will contain address of the next instruction that have to be executed.

5.Java Native Stack:   

  • Java native stack area is used for storing non-java coding available in the application. The non-java code is called as native code.

  

Execution Engine:

  • The Execution Engine of JVM is Responsible for executing the program and it contains two parts.
  1. Interpreter.
  2. JIT Compiler (just in time compiler).
  • The java code will be executed by both interpreter and JIT compiler simultaneously which will reduce the execution time and them by providing high performance. The code that is executed by JIT compiler is called as HOTSPOTS (company).
  



Java programming interview questions

  1. Java Program to Print prime numbers? 
  2. What happens if we place return statement in try catch blocks 
  3. Write a java program to convert binary to decimal 
  4. Java Program to convert Decimal to Binary
  6. Java program to restrict a class from creating not more than three objects
  7. Java basic interview programs on this keyword 
  9. Interfaces allows constructors? 
  10. Can we create static constructor in java 
  11. Super keyword interview questions java 
  12. Java interview questions on final keyword
  13. Can we create private constructor in java
  14. Java Program Find Second highest number in an integer array 
  15. Java interview programming questions on interfaces 
  16. Top 15 abstract class interview questions  
  17. Java interview Questions on main() method  
  19. Top 20 collection framework interview Questions
  20. Java Interview Program to find smallest and second smallest number in an array 
  21. Java Coding Interview programming Questions : Java Test on HashMap  
  22. Explain java data types with example programs 
  24. Constructor chaining in java with example programs 
  26. Swap two numbers without using third variable in java 
  27. Find sum of digits in java 
  28. How to create immutable class in java 
  29. AtomicInteger in java 
  30. Check Even or Odd without using modulus and division  
  31. String Reverse Without using String API 
  32. Find Biggest substring in between specified character
  33. Check string is palindrome or not?
  34. Reverse a number in java?
  35. Fibonacci series with Recursive?
  36. Fibonacci series without using Recursive?
  37. Sort the String using string API?
  38. Sort the String without using String API?
  39. what is the difference between method overloading and method overriding?
  40. How to find largest element in an array with index and value ?
  41. Sort integer array using bubble sort in java?
  42. Object Cloning in java example?
  43. Method Overriding in java?
  44. Program for create Singleton class?
  45. Print numbers in pyramid shape?
  46. Check armstrong number or not?
  47. Producer Consumer Problem?
  48. Remove duplicate elements from an array
  49. Convert Byte Array to String
  50. Print 1 to 10 without using loops
  51. Add 2 Matrices
  52. Multiply 2 Matrices
  53. How to Add elements to hash map and Display
  54. Sort ArrayList in descending order
  55. Sort Object Using Comparator
  56. Count Number of Occurrences of character in a String
  57. Can we Overload static methods in java
  58. Can we Override static methods in java 
  59. Can we call super class static methods from sub class 
  60. Explain return type in java 
  61. Can we call Sub class methods using super class object? 
  62. Can we Override private methods ? 
  63. Basic Programming Questions to Practice : Test your Skill
  64. Java programming interview questions on collections

Inner classes in java

Posted by: Instanceofjava Posted date: 2:23 PM / comment : 0

  • Class inside a class is known as nested class.
  • We will use nested classes to group classes and interfaces at one place for readability and maintainability.
  1. package com.instanceofjava;
  2. public class A{ 
  3.  class B{
  4. // inner class
  5. }
  6. }


  • Inner class is a part of nested class. Non-static nested classes are known as inner classes. 
  • Nested classes are two types
  • Non-static nested class(inner class)
    1. Member inner class
    2. Anonymous inner class
    3. Local inner class
  • Static nested class.

Member inner class:

  •  A class is defined within a class and outside of methods of that class known as member inner class.
  1. package instanceofjavaforus;
  2. public class A{ 
  3.  class B{
  4. public void show(){
  5. }
  6. }
  7. public static void main(String args[]){
  8. A a= new A();
  9. a.B b= a.new B();
  10. b.show();
  11. }
  12. }

 

Anonymous inner class:

  • Anonymous inner class is a inner class which does not have a name and whose instance is created at the time creating class itself.
  • Anonymous inner classes are somewhat different from normal classes in its creation.
  • There are two ways to create in two ways.
    1. Using class.
    2. Using interface.

Using class:

  1. package instanceofjavaforus;
  2. public class A{ 
  3. public void show(){
  4. }
  5. public static void main(String args[]){
  6. A a= new A(){
  7.  public void display(){
  8. System.out.println('anonymous class method');
  9. }
  10. };
  11. a.display();
  12. }
  13. }


  Using interface:

  1. package instanceofjavaforus;
  2. public interface A{ 
  3.  public void show();
  4. }

  1. package instanceofjavaforus;
  2. public class Demo{ 
  3. public static void main(String args[]){
  4. A a= new A(){
  5.  public void show(){
  6. System.out.println('anonymous class method');
  7. }
  8. };
  9. a.show();
  10. }
  11. }

 

Local inner class:

  • A class which is defined inside a method of another class known as local inner class
  1. package instanceofjavaforus;
  2. public class Demo{ 
  3. void create(){
  4. class A{
  5. void show(){
  6. System.out.println("local inner class method");
  7. }
  8. }
  9. A a= new A();
  10. a.show();
  11. }
  12. public static void main(String args[]){
  13. Demo obj= new Demo();
  14.  obj.create();
  15. }
  16. }

 

Static nested class:

  • A static nested class is a class which is defined inside a class as static.
  1. package instanceofjavaforus;
  2. public class Outer{ 
  3.   static class inner{
  4. public void show(){
  5. System.out.println("static inner class method");
  6. }
  7. }
  8. public static void main(String args[]){
  9. Outer.inner in= new Outer.innner();
  10. in.show();
  11. }
  12. }

Top 25 Core java interview questions for freshers

Posted by: Instanceofjava Posted date: 10:28 AM / comment : 2

1. what is a transient variable?

  •  A transient variable is a variable that whose value is not going to be serialized

2. What is synchronization?

  • With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources.
  •  Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object’s value. This often leads to significant errors.

3. What’s new with the stop(), suspend() and resume() methods in JDK 1.2? 

  • The stop(), suspend() and resume() methods have been deprecated in JDK 1.2.

4. Is null a keyword?

  •  "null"  is not a keyword. .null is a literal.

5. What state does a thread enter when it terminates its processing?

  • When a thread terminates its processing, it enters the dead state.

6. What is the Collections API?

  • The Collections API is a set of classes and interfaces that support operations on collections of objects.

7. What is the List interface?

  • The List interface provides support for ordered collections of objects which allows duplicate elements also.

8. What is the Vector class?

  • The Vector class provides the capability to implement a growable array of objects

9.Can we instantiate Abstract class?

  • We can not create object for abstract class directly. but indirectly through sub class object we can achieve it.

10.What is the first keyword used in a java program?

  • Its "package" keyword.

11.When a class should be defined as final?

  • If we do not want allow subclasses.
  • If we do not want to extend the functionality.

12.Can we declare abstract method as static?

  • No, we are not allowed to declare abstract method as static.
  • It leads to compilation error: illegal combination of modifiers abstract and static.

13.Can we apply abstract keyword to interface?

  • Yes, it is optional.
  • abstract interface A{}

14.Can we write empty interface?

  • Yes it is possible it is marker interface.
  • interface A{}

15.Can we declare interface as final?

  • No, it leads to compile time error. Because it should allow sub class.

16.How to solve ClassCastException?

  • To solve  ClassCastException we should use instanceof operator.
  • obj instanceof class_name

17. Is “xyz” a primitive value? 

  • No, it is not primitive it is string literal.

18.When is an object subject to garbage collection? 

  • An object is subject to garbage collection when it becomes unreachable to the program in which it is used.

19.What method must be implemented by all threads? 

  • The run() method, whether they are a subclass of Thread or implement the Runnable interface.


20.What happens if an exception is not caught?

  • An uncaught exception results in the uncaughtException() method of the thread’s ThreadGroup being invoked, which eventually results in the termination of the program in which it is thrown.

21.How are this() and super() used with constructors?

  • this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.

22.Under what conditions is an object’s finalize() method invoked by the garbage collector?

  • The garbage collector invokes an object’s finalize() method when it detects that the object has become unreachable.

23.What restrictions are placed on method overloading? 

  • Methods should have same name  and defer in parameters.

24.When does the compiler supply a default constructor for a class? 

  • The compiler supplies a default constructor for a class if no other constructors are provided.

25.What modifiers can be used with a local inner class?

  • A local inner class may be final or abstract.

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