Core Java Interview Questions. Coding compilers collected list of 399 core java interview questions for freshers to experienced developers. This list of interview questions includes, java interview questions for 3 years experience, core java interview questions for senior developers, java interview questions for 2 years experience, java interview questions for 5 years experience. We are sure that after going through these java interview questions, you will be in a position to handle any java job interview. Happy learning.!
Core Java Interview Questions
What Do You Mean By Platform Independence? |
Are Jvm’s Platform Independent?
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What Is A Jvm?
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What Is The Difference Between A Jdk And A Jvm?
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What Is A Pointer And Does Java Support Pointers?
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What Is The Base Class Of All Classes?
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Does Java Support Multiple Inheritance?
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Is Java A Pure Object Oriented Language?
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Are Arrays Primitive Data Types?
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What Is Difference Between Path And Classpath?
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What Are Local Variables?
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What Are Instance Variables?
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How To Define A Constant Variable In Java?
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Should A Main Method Be Compulsorily Declared In All Java Classes?
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What Is The Return Type Of The Main Method?
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Why Is The Main Method Declared Static?
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What Is The Arguement Of Main Method?
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Can A Main Method Be Overloaded?
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Can A Main Method Be Declared Final?
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Does The Order Of Public And Static Declaration Matter In Main Method?
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Can A Source File Contain More Than One Class Declaration?
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What Is A Package?
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Which Package Is Imported By Default?
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Can A Class Declared As Private Be Accessed Outside It’s Package?
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Can A Class Be Declared As Protected?
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What Is The Access Scope Of A Protected Method?
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What Is The Purpose Of Declaring A Variable As Final?
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What Is The Impact Of Declaring A Method As Final?
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I Don’t Want My Class To Be Inherited By Any Other Class. What Should I Do?
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Can You Give Few Examples Of Final Classes Defined In Java Api?
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How Is Final Different From Finally And Finalize?
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Can A Class Be Declared As Static?
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When Will You Define A Method As Static?
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What Are The Restriction Imposed On A Static Method Or A Static Block Of Code?
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I Want To Print “hello” Even Before Main Is Executed. How Will You Acheive That?
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What Is The Importance Of Static Variable?
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Can We Declare A Static Variable Inside A Method?
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What Is An Abstract Class And What Is It’s Purpose?
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Can A Abstract Class Be Declared Final?
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What Is Use Of A Abstract Variable?
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Can You Create An Object Of An Abstract Class?
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Can A Abstract Class Be Defined Without Any Abstract Methods?
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Class C Implements Interface I Containing Method M1 And M2 Declarations. Class C Has Provided Implementation For Method M2. Can I Create An Object Of Class C?
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Java Interview Questions for 2 Years ExperienceCan A Method Inside A Interface Be Declared As Final?
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Can An Interface Implement Another Interface?
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Can An Interface Extend Another Interface?
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Can A Class Extend More Than One Class?
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Why Is An Interface Be Able To Extend More Than One Interface But A Class Can’t Extend More Than One Class?
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Can An Interface Be Final?
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Can A Class Be Defined Inside An Interface?
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Can An Interface Be Defined Inside A Class?
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What Is A Marker Interface?
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Which Oo Concept Is Achieved By Using Overloading And Overriding?
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If I Only Change The Return Type, Does The Method Become Overloaded?
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Why Does Java Not Support Operator Overloading?
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Can We Define Private And Protected Modifiers For Variables In Interfaces?
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What Is Externalizable?
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What Modifiers Are Allowed For Methods In An Interface?
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What Is A Local, Member And A Class Variable?
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What Is An Abstract Method?
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What Value Does Read() Return When It Has Reached The End Of A File?
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Can A Byte Object Be Cast To A Double Value?
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What Is The Difference Between A Static And A Non-static Inner Class?
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A non-static inner class may have object instances that are associated with instances of the class’s outer class. A static inner class does not have any object instances.
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What Is An Object’s Lock And Which Object’s Have Locks?
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What Is The % Operator?
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When Can An Object Reference Be Cast To An Interface Reference?
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Which Class Is Extended By All Other Classes?
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Which Non-unicode Letter Characters May Be Used As The First Character Of An Identifier?
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What Restrictions Are Placed On Method Overloading?
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What Is Transient Variable?
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What Is Collection Api?
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What Is Casting?
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What Is The Return Type Of A Program’s Main() Method?
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If A Variable Is Declared As Private, Where May The Variable Be Accessed?
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What Do You Understand By Private, Protected And Public?
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What Is Downcasting ?
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What Modifiers May Be Used With An Inner Class That Is A Member Of An Outer Class?
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How Many Bits Are Used To Represent Unicode, Ascii, Utf-16, And Utf-8 Characters?
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What Restrictions Are Placed On The Location Of A Package Statement Within A Source Code File?
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What Is A Native Method?
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What Are Order Of Precedence And Associativity, And How Are They Used?
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Can An Anonymous Class Be Declared As Implementing An Interface And Extending A Class?
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What Is The Range Of The Char Type?
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What Is The Range Of The Short Type?
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Why Isn’t There Operator Overloading?
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What Does It Mean That A Method Or Field Is “static”?
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Is Null A Keyword?
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Which Characters May Be Used As The Second Character Of An Identifier,but Not As The First Character Of An Identifier?
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Is The Ternary Operator Written X : Y ? Z Or X ? Y : Z ?
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How Is Rounding Performed Under Integer Division?
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If A Class Is Declared Without Any Access Modifiers, Where May The Class Be Accessed?
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Does A Class Inherit The Constructors Of Its Superclass?
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Name The Eight Primitive Java Types.
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What Restrictions Are Placed On The Values Of Each Case Of A Switch Statement?
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What Is The Difference Between A While Statement And A Do Statement?
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What Modifiers Can Be Used With A Local Inner Class?
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When Does The Compiler Supply A Default Constructor For A Class?
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If A Method Is Declared As Protected, Where May The Method Be Accessed?
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What Are The Legal Operands Of The Instanceof Operator?
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Are True And False Keywords?
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What Happens When You Add A Double Value To A String?
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What Is The Diffrence Between Inner Class And Nested Class?
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Can An Abstract Class Be Final?
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What Is Numeric Promotion?
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What Is The Difference Between A Public And A Non-public Class?
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To What Value Is A Variable Of The Boolean Type Automatically Initialized?
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What Is The Difference Between The Prefix And Postfix Forms Of The ++ Operator?
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What Restrictions Are Placed On Method Overriding?
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What Is A Java Package And How Is It Used?
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What Modifiers May Be Used With A Top-level Class?
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What Is The Difference Between An If Statement And A Switch Statement?
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Can A Method Be Overloaded Based On Different Return Type But Same Argument Type ?
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What Happens To A Static Var That Is Defined Within A Method Of A Class ?
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How Many Static Init Can You Have ?
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What Is The Difference Between Method Overriding And Overloading?
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What Is Constructor Chaining And How Is It Achieved In Java ?
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What Is The Difference Between The Boolean & Operator And The && Operator?
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Which Java Operator Is Right Associative?
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Can A Double Value Be Cast To A Byte?
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Java Interview Questions for 3 Years Experience What Is The Difference Between A Break Statement And A Continue Statement?
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Can A For Statement Loop Indefinitely?
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To What Value Is A Variable Of The String Type Automatically Initialized?
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What Is The Difference Between A Field Variable And A Local Variable?
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How Are This() And Super() Used With Constructors?
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What Does It Mean That A Class Or Member Is Final?
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What Does It Mean That A Method Or Class Is Abstract?
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Can An Anonymous Class Be Declared As Implementing An Interface And Extending A Class?
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What Is The Catch Or Declare Rule For Method Declarations?
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What Are Some Alternatives To Inheritance?
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What Are The Different Identifier States Of A Thread?
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What Is Garbage Collection? What Is The Process That Is Responsible For Doing That In Java?
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What Kind Of Thread Is The Garbage Collector Thread?
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What Is A Daemon Thread?
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How Will You Invoke Any External Process In Java?
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What Is The Finalize Method Do?
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What Is Mutable Object And Immutable Object?
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What Is The Basic Difference Between String And Stringbuffer Object?
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What Is The Purpose Of Void Class?
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What Is Reflection?
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What Is The Base Class For Error And Exception?
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What Is The Byte Range?
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What Is The Implementation Of Destroy Method In Java.. Is It Native Or Java Code?
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What Are The Approaches That You Will Follow For Making A Program Very Efficient?
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What Is A Databasemetadata?
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What Is Locale?
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How Will You Load A Specific Locale?
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What Is Jit And Its Use?
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Is Jvm A Compiler Or An Interpreter?
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What Is The Purpose Of Assert Keyword Used In Jdk1.4.x?
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How Will You Get The Platform Dependent Values Like Line Separator, Path Separator, Etc., ?
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Is “abc” A Primitive Value?
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What Is Singleton?
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Can You Instantiate The Math Class?
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What Are The Methods In Object?
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What Is Aggregation?
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What Is Composition?
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What Is Inner Class?
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What Is Nested Class?
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What Is The Major Difference Between Linkedlist And Arraylist?
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What Is The Significance Of Listiterator?
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What Is The Final Keyword Denotes?
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What Is Skeleton And Stub? What Is The Purpose Of Those?
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Why Does It Take So Much Time To Access An Applet Having Swing Components The First Time?
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What Is The Difference Between Instanceof And Isinstance?
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What Does The “final” Keyword Mean In Front Of A Variable? A Method? A Class?
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Describe What Happens When An Object Is Created In Java?
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What Is The Difference Amongst Jvm Spec, Jvm Implementation, Jvm Runtime ?
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How Does Java Handle Integer Overflows And Underflows?
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Why Are There No Global Variables In Java?
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Whats The Difference Between Notify() And Notifyall()?
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How Can My Application Get To Know When A Httpsession Is Removed?
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What Interface Must An Object Implement Before It Can Be Written To A Stream As An Object?
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What Is Your Platform’s Default Character Encoding?
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What An I/o Filter?
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What Is The Purpose Of Finalization?
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Which Class Should You Use To Obtain Design Information About An Object?
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What Is The Purpose Of The System Class?
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Can We Use The Constructor, Instead Of Init(), To Initialize Servlet?
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How Can A Servlet Refresh Automatically If Some New Data Has Entered The Database?
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Java Interview Questions for 4 Years Experience The Code In A Finally Clause Will Never Fail To Execute, Right?
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How Many Messaging Models Do Jms Provide For And What Are They?
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What Information Is Needed To Create A Tcp Socket?
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What Class.forname Will Do While Loading Drivers?
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How Many Jsp Scripting Elements Are There And What Are They?
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What Are Stored Procedures? How Is It Useful?
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How Do I Include Static Files Within A Jsp Page?
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Why Does Jcomponent Have Add() And Remove() Methods But Component Does Not?
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How Can I Implement A Thread-safe Jsp Page?
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What Is The Difference Between Procedural And Object-oriented Programs?
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What Are Encapsulation, Inheritance And Polymorphism?
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What Is The Difference Between Assignment And Initialization?
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What Is Oops? |
What Are Class, Constructor And Primitive Data Types?
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What Is An Object And How Do You Allocate Memory To It?
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What Is The Difference Between Constructor And Method?
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What Are Methods And How Are They Defined?
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What Is The Use Of Bin And Lib In Jdk?
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How Many Ways Can An Argument Be Passed To A Subroutine And Explain Them?
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What Is The Difference Between An Argument And A Parameter?
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How Would You Implement A Thread Pool?
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What Are The Advantages And Disadvantages Of Reference Counting In Garbage Collection?
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Why Java Is Said To Be Pass-by-value ?
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What Are The Access Modifiers Available In Java?
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What Is The Difference Between A Switch Statement And An If Statement?
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What Are Synchronized Methods And Synchronized Statements?
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What Are The Different Ways In Which A Thread Can Enter Into Waiting State?
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What Is The Difference Between Static And Non Static Variables ?
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What Is The Difference Between Notify And Notifyall Method?
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What Are Different Type Of Exceptions In Java?
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Explain About The Select Method With An Example?
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Can There Be An Abstract Class With No Abstract Methods In It?
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Can We Define Private And Protected Modifiers For Variables In Interfaces?
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What Is Garbage Collection? What Is The Process That Is Responsible For Doing That In Java?
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Can There Be An Abstract Class With No Abstract Methods In It?
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Can An Interface Have An Inner Class?
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What Is User Defined Exception?
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What Is The Difference Between Logical Data Independence And Physical Data Independence?
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What Are The Practical Benefits, If Any, Of Importing A Specific Class Rather Than An Entire Package (e.g. Import Java.net.* Versus Import Java.net.socket)?
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How Many Methods Do U Implement If Implement The Serializable Interface?
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What Does The “abstract” Keyword Mean In Front Of A Method? A Class?
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You Can Create A String Object As String Str = “abc”; Why Cant A Button Object Be Created As Button Bt = “abc”;? Explain
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Can Rmi And Corba Based Applications Interact ?
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What Is Passed By Reference And Pass By Value ?
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What Is A “stateless” Protocol ?
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Difference Between A Class And An Object ?
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What Are The Four Corner Stones Of Oop?
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What Gives Java It’s “write Once And Run Anywhere” Nature?
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How Can A Dead Thread Be Restarted?
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What Happens If An Exception Is Not Caught?
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What Is A Compilation Unit?
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What Is A Task’s Priority And How Is It Used In Scheduling?
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What Value Does Readline() Return When It Has Reached The End Of A File?
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Can An Object’s Finalize() Method Be Invoked While It Is Reachable?
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Does Garbage Collection Guarantee That A Program Will Not Run Out Of Memory?
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Is Sizeof A Keyword?
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What State Does A Thread Enter When It Terminates Its Processing?
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Can A Lock Be Acquired On A Class?
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How Are Observer And Observable Used?
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What Is A Transient Variable?
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Wha Is The Output From System.out.println(“hello”+null); ?
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What Are E And Pi?
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If An Object Is Garbage Collected, Can It Become Reachable Again?
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Can An Exception Be Rethrown?
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What Is The Purpose Of The File Class?
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Is A Class Subclass Of Itself?
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What Modifiers May Be Used With An Interface Declaration?
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What Classes Of Exceptions May Be Caught By A Catch Clause?
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What Is The Difference Between The Reader/writer Class Hierarchy And The Inputstream/outputstream Class Hierarchy?
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Can An Object Be Garbage Collected While It Is Still Reachable?
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What Is An Object’s Lock And Which Object’s Have Locks?
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How Are Commas Used In The Intialization And Iteration Parts Of A For Statement?
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What Must A Class Do To Implement An Interface?
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What Is The Difference Between Preemptive Scheduling And Time Slicing?
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What Restrictions Are Placed On The Location Of A Package Statement Within A Source Code File?
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What Are Wrapped Classes?
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Is It Possible To Specify Multiple Jndi Names When Deploying An Ejb?
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What Is Java And Their Uses?
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What Is Hotjava?
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How Can You Say Java Is Object Oriented?
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Why Java Is Platform Independent? Explain.
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Why Java Is Secure? Explain.
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Why Do People Says “java Is Robust”?
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How Java Is Similar To C?
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What’s The Difference Between Applets And Standalone Program?
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Why Java Applets Are More Useful For Intranets As Compared To Internet?
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How Can You Set The Applet Size?
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How Can You Set An Applet’s Height And Width As A Percentage?
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What Is Codebase?
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What Is Appletviewer?
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Explain, Java Is Compatible With All Servers But Not All Browsers?
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What Is The Program Development Process?
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What Is The File Type?
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What Is Javac_g?
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How To Optimize The Javac Output?
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What Is The Difference Between Java Applets And Applications?
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Can You Explain The Cs Option Of Java Interpreter?
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What Is The Statements?
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What Is Style And Indentation?
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What Is The Program Compilation Process?
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What Is Java Literals?
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What Is The Primitive Type Byte?
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What Is The Primitive Type Short?
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Why Call By Value Prevents Parameter Value Change?
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What Is Remote Method Invocation (rmi)?
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What Is Java Jit Compilers?
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What Is The Java Idl System?
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What Is Java Beans?
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What Is Object-oriented Programming?
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What Is Abstraction?
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What Is Encapsulation?
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How Does The Application Server Handle The Jms Connection?
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What Is A Superclass?
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Explain The Abstract Class Modifier?
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What Is The Final Class Modifier?
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Explain The Public Class Modifier.
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What Is The Public Field Modifier?
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Explain The Private Field Modifier?
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Explain The Protected Field Modifier?
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Can You Explain The Private Protected Field Modifier?
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What Is The Static Field Modifier?
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What Is The Final Field Modifier?
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Explain The Transient Field Modifier?
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Explain The Use Of Volatile Field Modifier?
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What Is Default Constructors?
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What Is The Public Method Modifier?
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What Is The Private Method Modifier?
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What Is The Protected Method Modifier?
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Explain The Private Protected Method Modifier?
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Can You Explain The Final Method Modifier?
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What Is The Abstract Method Modifier?
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What Is The Synchronized Method Modifier?
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Explain The Init Method?
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What Is The Destroy Method?
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What Is Multithreading?
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Java Interview Questions for 5 Years Experience How Java Uses The String And Stringbuffer Classes?
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What Is The Epoch Date?
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What Is An Arrays?
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What Is Binary Search?
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Can A Private Method Of A Superclass Be Declared Within A Subclass?
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What Is Quick Sort?
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What Is The Difference Between Final, Finally And Finalize?
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In System.out.println( ), What Is System, Out And Println?
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What Is Meant By “abstract Interface”?
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What Is The Difference Between Swing And Awt Components?
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Why Java Does Not Support Pointers?
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What Are Parsers? Dom Vs Sax Parser.
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What Is A Platform?
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What Is The Main Difference Between Java Platform And Other Platforms?
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What Is The Java Virtual Machine?
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What Is The Java Api?
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What Is The Package?
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What Is Native Code?
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Is Java Code Slower Than Native Code?
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What Is The Serialization?
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How To Make A Class Or A Bean Serializable?
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How Many Methods Are There In The Serializable Interface?
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How Many Methods Are There In The Externalizable Interface?
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Which Containers Use A Border Layout As Their Default Layout?
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What Is Synchronization And Why Is It Important?
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What Are Three Ways In Which A Thread Can Enter The Waiting State?
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What Is The Preferred Size Of A Component?
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Can Java Object Be Locked Down For Exclusive Use By A Given Thread?
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Can Each Java Object Keep Track Of All The Threads That Want To Exclusively Access It?
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What Is The Purpose Of The Wait(), Notify() And Notifyall() Methods?
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What Are The High-level Thread States?
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What Is The Collections Api?
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What Is The List Interface?
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How Many Bits Are Used To Represent Unicode, Ascii, Utf-16 And Utf-8 Characters?
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What Is The Properties Class?
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What Is The Purpose Of The Runtime Class?
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What Is The Purpose Of The Finally Clause Of A Try-catch-finally Statement?
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What Is The Locale Class?
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What Is A Protected Method?
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What Is A Static Method?
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What Is The Difference Between A Window And A Frame?
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What Are Peerless Components?
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What Is The Difference Between The Reader/writer Class Hierarchy And The Inputstream/outputstream Class Hierarchy?
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What Is The Difference Between Throw And Throws Keywords?
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Name Primitive Java Types?
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How Can A Gui Component Handle Its Own Events?
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What Advantage Do Java’s Layout Managers Provide Over Traditional Windowing Systems?
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What Are The Problems Faced By Java Programmers Who Don’t Use Layout Managers?
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What Is The Difference Between Static And Non-static Variables?
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What Is The Difference Between The Paint() And Repaint() Methods?
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What Is A Container In A Gui?
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Is Iterator A Class Or Interface? What Is Its Use?
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How You Can Force The Garbage Collection?
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Describe The Principles Of Oops?
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Explain The Encapsulation Principle?
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Explain The Inheritance Principle?
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How To Define An Abstract Class?
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How To Define An Interface?
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Explain The Polymorphism Principle?
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Explain The Different Forms Of Polymorphism?
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What Are Access Specifiers Available In Java?
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What Do You Understand By A Variable?
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What Do You Understand By Numeric Promotion?
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Differentiate Between A Class And An Object.
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What Is The Use Of Object And Class Classes?
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What Do You Understand By Casting In Java Language?
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What Are The Types Of Casting?
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What Do You Understand By Downcasting?
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What Do You Understand By Final Value?
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What Are Keyboard Events?
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What Is The Intersection And Union Methods?
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What Are Controls And Their Different Types In Awt?
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What Is The Difference Between Choice And List?
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What Is The Difference Between Scrollbar And Scrollpane?
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Which Containers Use A Flow Layout As Their Default Layout?
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What Are Wrapper Classes?
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What Is The Difference Between Set And List?
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How Can The Checkbox Class Be Used To Create A Radio Button?
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Which Textcomponent Method Is Used To Set A Textcomponent To The Read-only State?
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What Methods Are Used To Get And Set The Text Label Displayed By A Button Object?
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What Is The Difference Between Yield() And Sleep()?
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How To Handle A Web Browser Resize Operation?
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Explain The Concept Of Hashtables?
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Must Read Java Interview Questions Books 2019
- Java Interview Guide: How to Build Confidence with a Solid Understanding of Core Java Principles
- Core JAVA Interview Questions You’ll Most Likely Be Asked: Volume 8 (Job Interview Questions)
- Java / J2EE: Interview Questions You’ll Most Likely Be Asked: Volume 10 (Job Interview Questions)
- 500+ Java & J2ee Interview Questions & Answers: Java & J2ee Programming
- Java / J2EE Interview Questions: A Guide for Interview
- Java/J2EE Job Interview Companion
- Data Structures and Algorithms Made Easy in Java: Data Structure and Algorithmic Puzzles
- Cracking the C, C++ and Java Interview
- JAVA/J2EE: Interview Questions (With Set of 2 CDs)
- Java Programming Interviews Exposed (WROX)
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