JAVA INTERVIEW QUESTIONS

1) Variable names should start with small letters.2) Variable names should be nouns3) Short meaningful names are recommended.4) If there are multiple words every innerword should start with Uppecase character.Ex : string,value,empName,empSalary

1) Method names should start with small letters.2) Method names are usually verbs3) If method contains multiple words, every inner word should start with uppercase letter.Ex : toString()4) Method name must be combination of verb and nounEx : getCarName(),getCarNumber()

1) Interface should start with uppercase letters2) Interfaces names should be adjectivesExample : Runnable, Serializable, Marker, Cloneable

Sun has created Java Coding standards or Java Coding Conventions . It is recommended highly to followjava coding standards.Classnames should start with uppercase letter. Classnames names should be nouns. If Class name is ofmultiple words then the first letter of inner word must be capital letter.Ex : Employee, EmployeeDetails, ArrayList, TreeSet, HashSet

The right shift operator ‘>>’ shifts all of the bits in a value to the right to a specified number of times.int a =15;a= a >> 3;The above line of code moves 15 three characters right. The unsigned shift operator ‘>>>’ used to shift right. The places which were vacated by shift are filledwith zeroes.

Constants are fixed values whose values cannot be changed during the execution of program. We createconstants in java using final keyword.Ex : final int number =10;final String str=”java-interview –questions”

Character constant is enclosed in single quotes. String constants are enclosed in double quotes. Characterconstants are single digit or character. String Constants are collection of characters.Ex :’2’, ‘A’Ex : “Hello World”

Unicode is a character set developed by Unicode Consortium. To support all languages in the world Javasupports Unicode values. Unicode characters were represented by 16 bits and its character range is 0-65,535.Java uses ASCII code for all input elements except for Strings, identifiers, and comments.

ASCII stands for American Standard code for Information Interchange. ASCII character range is 0 to 255.We can’t add more characters to the ASCII Character set. ASCII character set supports only English. That13is the reason, if we see C language we can write c language only in English we can’t write in otherlanguages because it uses…

length() : In String class we have length() method which is used to return the number of characters instring.Ex : String str = “Hello World”;System.out.println(str.length());Str.length() will return 11 characters including space.length : we have length instance variable in arrays which will return the number of values or objects inarray.For example :String days[]={” Sun”,”Mon”,”wed”,”thu”,”fri”,”sat”};Will return 6…

A constructor is a special method used to initialize objects in java.we use constructors to initialize all variables in the class when an object is created. As and when an objectis created it is initialized automatically with the help of constructor in java.We have two types of constructorsDefault ConstructorParameterized ConstructorSignature : public classname(){}Signature : public…

public : “public” is an access specifier which can be used outside the class. When main method is declaredpublic it means it can be used outside class.static : To call a method we require object. Sometimes it may be required to call a method without thehelp of object. Then we declare that method as static.…

The process of wrapping or putting up of data in to a single unit class and keeps data safe from misuse is called encapsulation . Through encapsulation we can hide and protect the data stored in java objects. Java supports encapsulation through access control. There are four access control modifiers in java public , private,…

It contains the executable body that can be applied to the specific object of the class.Method includes method name, parameters or arguments and return type and a body of executable code.Syntax : type methodName(Argument List){}ex : public float add(int a, int b, int c)methods can have multiple arguments. Separate with commas when we have multiple…

Classes are fundamental or basic unit in Object Oriented Programming . A class is kind of blueprint or template for objects. Class defines variables, methods. A class tells what type of objects we are creating. For example take Department class tells us we can create department type objects. We can create any number of department…

this() is used to access one constructor from another with in the same class while super() is used to access superclass constructor. Either this() or super() exists it must be the first statement in the constructor.

When a javac compiler compiler compiles a class it generates .class file. This .class file contains set of instructions called byte code. Byte code is a machine independent language and contains set of instructions which are to be executed only by JVM. JVM can understand this byte codes.

JIT compiler stands for Just in time compiler. JIT compiler compiles byte code in to executable code . JIT is a part of JVM . JIT cannot convert complete java program in to executable code it converts as and when it is needed during execution.

A class having two or more methods with same name but with different arguments then we say that those methods are overloaded.Static polymorphism is achieved in java using method overloading.Method overloading is used when we want the methods to perform similar tasks but with different inputs or values.When an overloaded method is invoked, java first…

The most unique feature of java is platform independent. In any programming language source code is compiled in to executable code . This cannot be run across all platforms. When javac compiles a java program it generates an executable file called .class file. Class file contains byte codes. Byte codes are interpreted only by JVM’s…