Interview and viva Questions For Java

Interview Questions for Java

Question : 1

What do you know about Java?

Question : 2

What are the supported platform by Java Programming Language?

Question : 3

List any five features of Java?

Question : 4

Why is Java Architectural Neutral?

Question : 5

How Java enabled High Performance?

Question : 6

Why Java is considered dynamic?

Question : 7

What is Java Virtual Machine and how it is considered in context of Java's platform independent feature?

Question : 8

List two Java IDE's?

Question : 9

List some Java keywords(unlike C, C++ keywords)?

Question : 10

What do you mean by Object?

Question : 11

Define class?

Question : 12

What kind of variables a class can consist of?

Question : 13

What is a Local Variable

Question : 14

What is a Instance Variable

Question : 15

What is a Class Variable

Question : 16

What is Singleton class?

Question : 17

What do you mean by Constructor?

Question : 18

List the three steps for creating an Object for a class?

Question : 19

What is the default value of byte datatype in Java?

Question : 20

What is the default value of float and double datatype in Java?

Question : 21

When a byte datatype is used?

Question : 22

What is a static variable?

Question : 23

What do you mean by Access Modifier?

Question : 24

What is protected access modifier?

Question : 25

What do you mean by synchronized Non Access Modifier?

Question : 26

: According to Java Operator precedence, which operator is considered to be with highest precedence?

Question : 27

Variables used in a switch statement can be used with which datatypes?

Question : 28

When parseInt() method can be used?

Question : 29

Why is String class considered immutable?

Question : 30

Why is StringBuffer called mutable?

Question : 31

What is the difference between StringBuffer and StringBuilder class?

Question : 32

Which package is used for pattern matching with regular expressions?

Question : 33

java.util.regex consists of which classes?

Question : 34

What is finalize() method?

Question : 35

What is an Exception?

Question : 36

What do you mean by Checked Exceptions?

Question : 37

What do you mean by Checked Exceptions?

Question : 38

Explain Runtime Exceptions?

Question : 39

Which are the two subclasses under Exception class?

Question : 40

When throws keyword is used?

Question : 41

When throw keyword is used?

Question : 42

How finally used under Exception Handling?

Question : 43

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

Question : 44

Define Inheritance?

Question : 45

When super keyword is used?

Question : 46

What is Polymorphism?

Question : 47

What is Abstraction?

Question : 48

What is Abstract class

Question : 49

When Abstract methods are used?

Question : 50

What is Encapsulation?

Question : 51

What is the primary benefit of Encapsulation?

Question : 52

What is an Interface?

Question : 53

Give some features of Interface?

Question : 54

Define Packages in Java?

Question : 55

Why Packages are used?

Question : 56

What do you mean by Multithreaded program?

Question : 57

What are the two ways in which Thread can be created?

Question : 58

What is an applet?

Question : 59

An applet extend which class?

Question : 60

Explain garbage collection in Java?

Question : 61

Define immutable object?

Question : 62

Explain the usage of this() with constructors?

Question : 63

Explain Set Interface?

Question : 64

Explain TreeSet?

Question : 65

What is Comparable Interface?

Question : 66

Difference between throw and throws?

Question : 67

Explain the following line used under Java Program: public static void main (String args[ ])

Question : 68

Define JRE i.e. Java Runtime Environment?

Question : 69

What is JAR file?

Question : 70

What is a WAR file?

Question : 71

Define JIT compiler?

Question : 72

What is the difference between object oriented programming language and object based programming language?

Question : 73

What is the purpose of default constructor?

Question : 74

Can a constructor be made final?

Question : 75

What is static block?

Question : 76

Define composition?

Question : 77

What is function overloading?

Question : 78

What is function overriding?

Question : 79

Difference between Overloading and Overriding?

Question : 80

What is final class?

Question : 81

What is NullPointerException?

Question : 82

What are the ways in which a thread can enter the waiting state?

Question : 83

How does multi-threading take place on a computer with a single CPU?

Question : 84

What invokes a thread's run() method?

Question : 85

Does it matter in what order catch statements for FileNotFoundException and IOException are written?

Question : 86

What is the difference between yielding and sleeping?

Question : 87

Why Vector class is used?

Question : 88

How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?

Question : 89

What are Wrapper classes?

Question : 90

What is the difference between a Window and a Frame?

Question : 91

Which package has light weight components?

Question : 92

What is the difference between the paint() and repaint() methods?

Question : 93

What is the purpose of File class?

Question : 94

What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?

Question : 95

Which class should you use to obtain design information about an object?

Question : 96

What is the difference between static and non-static variables?

Question : 97

What is Serialization and deserialization?

Question : 98

What are use cases?

Question : 99

Explain the use of sublass in a Java program?

Question : 100

How to add menushortcut to menu item?

Question : 101

Can you write a Java class that could be used both as an applet as well as an application?

Question : 102

What is the difference between Swing and AWT components?

Question : 103

What's the difference between constructors and other methods?

Question : 104

Is there any limitation of using Inheritance?

Question : 105

When is the ArrayStoreException thrown?

Question : 106

Can you call one constructor from another if a class has multiple constructors?

Question : 107

the difference between the methods sleep() and wait()?

Question : 108

When ArithmeticException is thrown?

Question : 109

What is a transient variable?

Question : 110

What is synchronization?

Question : 111

What is the Collections API?

Question : 112

Does garbage collection guarantee that a program will not run out of memory?

Question : 113

The immediate superclass of the Applet class?

Question : 114

Which Java operator is right associative?

Question : 115

What is the difference between a break statement and a continue statement?

Question : 116

If a variable is declared as private, where may the variable be accessed?

Question : 117

What is the purpose of the System class?

Question : 118

List primitive Java types?

Question : 119

What is the relationship between clipping and repainting under AWT?

Question : 120

Which class is the immediate superclass of the Container class?

Question : 121

What class of exceptions are generated by the Java run-time system?

Question : 122

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

Question : 123

How can a dead thread be restarted?

Question : 124

Which arithmetic operations can result in the throwing of an ArithmeticException?

Question : 125

Variable of the boolean type is automatically initialized as?

Question : 126

Can try statements be nested?

Question : 127

What are ClassLoaders?

Question : 128

What is the difference between an Interface and an Abstract class?

Question : 129

What will happen if static modifier is removed from the signature of the main method?

Question : 130

What is the default value of an object reference declared as an instance variable?

Question : 131

Can a top level class be private or protected?

Question : 132

Why do we need wrapper classes?

Question : 133

What is the difference between error and an exception?

Question : 134

Is it necessary that each try block must be followed by a catch block?

Question : 135

When a thread is created and started, what is its initial state?

Question : 136

What is the Locale class?

Question : 137

What are synchronized methods and synchronized statements?

Question : 138

What is runtime polymorphism or dynamic method dispatch?

Question : 139

What is Dynamic Binding(late binding)?

Question : 140

Can constructor be inherited?

Question : 141

What are the advantages of ArrayList over arrays?

Question : 142

Why deletion in LinkedList is fast than ArrayList?

Question : 143

How do you decide when to use ArrayList and LinkedList?

Question : 144

What is a Values Collection View ?

Question : 145

What is dot operator?

Question : 146

Where and how can you use a private constructor?

Question : 147

What is type casting?

Question : 148

Describe life cycle of thread?

Question : 149

What is the difference between the >> and >>> operators?

Question : 150

Which method of the Component class is used to set the position and size of a component?

Question : 151

What is the range of the short type?

Question : 152

What is the immediate superclass of Menu?

Question : 153

Does Java allow Default Arguments?

Question : 154

Which number is denoted by leading zero in java?

Question : 155

Which number is denoted by leading 0x or 0X in java?

Question : 156

Break statement can be used as labels in Java?

Question : 157

Where import statement is used in a Java program?

Question : 158

Explain suspend() method under Thread class>

Question : 159

Explain isAlive() method under Thread class?

Question : 160

What is currentThread()?

Question : 161

Explain main thread under Thread class execution?

Question : 162

Life cycle of an applet includes which steps?

Question : 163

Why is the role of init() method under applets?

Question : 164

Which method is called by Applet class to load an image?

Question : 165

Define code as an attribute of Applet?

Question : 166

Define canvas?

Question : 167

Define Network Programming?

Question : 168

What is a Socket?

Question : 169

Advantages of Java Sockets?

Question : 170

Disadvantages of Java Sockets?

Question : 171

Which class is used by server applications to obtain a port and listen for client requests?

Question : 172

Which class represents the socket that both the client and server use to communicate with each other?

Question : 173

Why Generics are used in Java?

Question : 174

What environment variables do I need to set on my machine in order to be able to run Java programs?

Question : 175

Is there any need to import java.lang package?

Question : 176

What is Nested top-level class?

Question : 177

What is Externalizable interface?

Question : 178

If System.exit (0); is written at the end of the try block, will the finally block still execute?

Question : 179

What is daemon thread?

Question : 180

Which method is used to create the daemon thread?

Question : 181

Which method must be implemented by all threads?

Question : 182

What is the GregorianCalendar class?

Question : 183

What is the SimpleTimeZone class?

Question : 184

What is the difference between the size and capacity of a Vector?

Question : 185

Can a vector contain heterogenous objects?

Question : 186

What is an enumeration?

Question : 187

What is difference between Path and Classpath?

Question : 188

Can a class declared as private be accessed outside it's package?

Question : 189

What are the restriction imposed on a static method or a static block of code?

Question : 190

Can an Interface extend another Interface?

Question : 191

Which object oriented Concept is achieved by using overloading and overriding?

Question : 192

What is an object's lock and which object's have locks?

Question : 193

What is Downcasting?

Question : 194

What are order of precedence and associativity and how are they used?

Question : 195

If a method is declared as protected, where may the method be accessed?

Question : 196

What is the difference between inner class and nested class?

Question : 197

What restrictions are placed on method overriding?

Question : 198

What is constructor chaining and how is it achieved in Java?

Question : 199

Can a double value be cast to a byte?

Question : 200

How does a try statement determine which catch clause should be used to handle an exception?

Question : 201

What will be the default values of all the elements of an array defined as an instance variable?

Question : 202

What is the difference between an Interface and an Abstract class?

Question : 203

What is the purpose of garbage collection in Java, and when is it used?

Question : 204

Describe synchronization in respect to multithreading.

Question : 205

Explain different way of using thread?

Question : 206

What is JDK?

Question : 207

What is the significance of the .class file?

Question : 208

How many classes can be declared in a Java program?

Question : 209

How is the main() method invoked?

Question : 210

How many classes can contain the main() method in a Java program?

Question : 211

What is the out object?

Question : 212

Why do you need to put an �f'� literal after a floating point constant?

Question : 213

Does Java support multiple inheritance?

Question : 214

Can I instantiate an interface?

Question : 215

What is the return value of the getContentPane()method?

Question : 216

What is the difference between a frame and a dialog box?

Question : 217

Can you write a java code that works both as an applet and an application?

Question : 218

Can I put more than one applet on a Web page?

Question : 219

How do I determine the width and the height of my applet?

Question : 220

Should applets have constructors?

Question : 221

Why do I get RuntimeAccessPermission exception when I am trying to execute a Java program which will load an image?

Question : 222

Why does my program not load the image even when the gif files are present in the specified directory?

Question : 223

When do I need to flush an output stream?

Question : 224

What is the advantage of Buffered streams over normal streams?

Question : 225

How do I read a line of input at a time?

Question : 226

What is meant by Serialization?

Question : 227

Give two examples of real world objects. Also specify their characteristics and behaviour.

Question : 228

What do you understand by state of an object? Explain with an example.

Question : 229

How are objects implemented in Software?

Question : 230

What is abstraction? How is encapsulation related to it?

Question : 231

Define Encapsulation.

Question : 232

Explain the term object using an example.

Question : 233

What is Object Oriented Programming?

Question : 234

Give a real life example of Polymorphism.

Question : 235

What is Java API?

Question : 236

Define the term Byte Code.

Question : 237

What is JVM? Explain its relationship with byte code.

Question : 238

What is a platform? How does it differ from a Java platform?

Question : 239

State the difference between Applet and Application.

Question : 240

What makes Java suitable to create secured applications?

Question : 241

What does the Robust feature in Java mean?

Question : 242

What is Multithreading in Java?

Question : 243

What makes Java Architecture Neutral?

Question : 244

What is WORA?

Question : 245

Explain the statement “Byte code is the object code for the JVM”

Question : 246

State two differences between fundamental and user-defined data type.

Question : 247

State two differences between a class and an object.

Question : 248

Why is a class called a user defined data type?

Question : 249

What is an access specifier? Which two access specifier is used in a class declaration?

Question : 250

Why is a class called an object factory?

Question : 251

State two rules you should follow for naming a class

Question : 252

What two conventions you should follow naming a class?

Question : 253

State two conventions you should follow while naming a class.

Question : 254

How are Decimal, Octal and Hexadecimal integer literals represented in Java?

Question : 255

What are separators?

Question : 256

What is Type Conversion? Name the two type conversions in Java.

Question : 257

What is an operator? How is the classification of operators based upon?

Question : 258

What is an expression?

Question : 259

What is an accumulator?

Question : 260

What is a bug? What is debugging?

Question : 261

What are the different type of errors that may occur in a Java program?

Question : 262

What are syntax errors? Give two examples.

Question : 263

What are run-time errors? Give two examples.

Question : 264

What are comments? Name the different types of comments used in Java.

Question : 265

Give two examples of real world objects. Also specify their characteristics and behaviour.