by Dinesh Thakur

A computer cannot store characters or integers. Computer can store information in the form of bits and bytes. The bit is a basic unit of information in computer. A bit can only have two values: yes or no, true or false, 1 or 0.



 
by Dinesh Thakur

The scope of a variable specifies the region of the source program where that variable is known, accessible and can be used. In Java, the declared variable has a definite scope. When a variable is defined within a class, its scope determines whether it can be used only within the defined class or outside of the class also.



 
by Dinesh Thakur

Operators work on the same data type. However, Java has wide variety of data types from which we can choose the suitable for a particular purpose. To perform the operation on variables from two different types of data we have to convert Both types to the same .



 
by Dinesh Thakur

The final modifier indicates that an object is fixed and cannot be changed. When we use this modifier at a class level, it means that the class can never have subclasses. When we apply this modifier to a method, the method can never be overridden. When we apply this modifier to a variable, the value of the variable remains constant. We will get a compile-time error if we try to override a final method or class. We will also get a compile-time error if we try to change the value of a final variable.

 
by Dinesh Thakur

Static are the members or variables which are defined independently of any object of that class. Static members are the members that can be used by itself, without reference to a specific instance. We can declare both methods and variables to be static. The variables declared as static are global variables. When objects of the class are declared, no copy of a static variable is made. Instead, all instances of the class share the same static variable.

 
by Dinesh Thakur

Variables are useful when you need to store information that can be changed as program runs. However, there may be certain situations in the program in which the value of variable should not be allowed to modify. This is accomplished using a special type of variable known as final variable. The final variable also called constant variable. It is a variable with a value that cannot be modified during the execution of the program.



 
by Dinesh Thakur

Type casting is the process of "casting"(Casting mean ‘conversion’ of value to another type) of value to one type to another type of variable.

 
by Dinesh Thakur

In Volume of a Sphere in Java Example , Math.PI is used because it denotes the value of pi i.e. 3.1414. Math.pow(r,3.0) is used for computing y3



 
by Dinesh Thakur

Sometimes you have to work with characters that are not listed on the keyboard or with characters that have a special meaning, as symbol as a "newline." They can not be displayed directly in the source the program code, and to use them we need special techniques that will look at now.

 
by Dinesh Thakur

step 1: Read a character

step 2: Cast it into byte and store in b

step 3: Print b

step 4: Exit

 
by Dinesh Thakur

When the block is declared without using any modifier, then it is treated as the non-static block is first executed before the constructor is executed. Non-static block directly access the static variable and instance variable.

 
by Dinesh Thakur

The static modifier is associated only with methods and variables, not classes. The static modifier is used to specify variables that can only be declared once. Static methods are used to specify methods that should not be overridden in subclasses.

 
by Dinesh Thakur

1. When the variable is declared outside the method, block, and constructor without using any modifier then it is treated as instance variable.
2. If the instance variable is not initialized then it takes the default value of the data type when the object is constructed.
3. Instance variable can use any access specifier.
4. It is accessed within the static method through the object of the class and within the non-static method and constructor directly without creating any object within the class, but outside the class non-static method and constructor invoke instance variable through objects.
5. Instance variable is also known as object level variable as for every instance the value of instance variable is newly initialized.



 
by Dinesh Thakur
  1. When the variable is declared within the method, block and constructor then the variable is treated as local variable.
  2. Local variable must be initialized before you call it otherwise it generates compile time error.
  3. Same local variable can be declared in two different blocks.
  4. Local variable never use any access specifier. It only takes the default access specifier.
  5. Local variable can never be declared through any access specifier except default access specifier.
 
by Dinesh Thakur

This Java byte Example shows how to use Java primitive byte variable inside a java class. The byte is a 8 bit signed type ranges from –128 to 127. The syntex For Declare byte varibale is byte <variable name> = <default value>;



 
by Dinesh Thakur

This Java boolean Variable Example shows how to use Java boolean variable inside a java class. The boolean data type which can have only two values, true or false.



 
by Dinesh Thakur

This Convert int to string java example shows how to convert int to String in Java.



 
by Dinesh Thakur

This Swap Numbers Without Using Third Variable Java Example shows how to exchange numbers without using third variable using java. i.e. if the input is n1 100 and n2 200 then after swaping output will be n1 is 200 and n2 is 100. You should not use any temporary variable to swap the numbers.



 
by Dinesh Thakur

This Swap Numbers Java Example program prints exchange number i.e. if the input is n1 is 100 and n2 is 200 then after swaping output will be n1 is 200 and n2 is 100. You should use any temporary variable to swap the numbers.



 
by Dinesh Thakur

This Reverse Number using Java program prints reverse number using numeric operations i.e. if the input is 564 then output will be 465. we can see after reversing the integer is print the integer digits in reverse order.



 
by Dinesh Thakur

This JavaInterfaceExample shows, An interface is a blueprint of a class. its functions should be public and abstract. We use the interface Keyword to define an interface. if a class implementing an interface should use the implements keyword as we see in our example class JavaInterface implements InterfaceExample . No need to creating objects for an interface. Interfaces don't have constructors as they can't be initiated. An Interface can be extends by one or more interfaces.

 
by Dinesh Thakur

This JavaFactorialUsingRecursion Example shows shows how to generate factorial of a given number using recursive function. Recursive are the function which calling method itself. the java recursion factorial example demonstrate recursive function call to find factorial. In mathematics, factorial is defined as n! = n*(n-1)...2*1. e.g. If we want to calculate factorial of 10 , then its factorial value is (10*9*8*7*6*5*4*3*2*1) = 3628800.



 
by Dinesh Thakur

This Java Factorial Example shows how to finds factorial of a given number using Java. Entered number is checked first if its negative then an error message is printed.



 
by Dinesh Thakur

In the Following example LargestandSmallestnumber shows how to Find Largest and Smallest Number in an Array Using Java Example



 
by Dinesh Thakur

In the Following example OddorEvenNumbers use mod operator to check if the number is even or odd. If the number divided by 2 and the reminder is 0 then number is even, otherwise the number is odd.

 
by Dinesh Thakur

In the Following example AreaofRectangleExample shows how to Calculate Area of Rectangle is length * width.

 
by Dinesh Thakur

In the Following example PerimeterofCircleExample shows how to Calculate Perimeter of Circle using 2*pi*r. where r is a radius of a circle.

 
by Dinesh Thakur

In the Following example AreaofCircleExample shows how to Calculate Area of Circle using pi*r*r. where r is a radius of a circle.

 
by Dinesh Thakur

Java's built-in data types called primitive data types. The primitive data types are int, byte, short, long, float, double, char, and boolean. A variable of any of these data types is called a primitive variable. We explain primitive data types in more detail as follows:



 
by Dinesh Thakur

Operator is a symbol that represents some operation that can be performed on data. The operators are applied to operands (onto which processing is desired). These operands can be literals, variables etc. The operators supported by Java are as follows:



 
by Dinesh Thakur

The Exit statement allows you to exit prematurely from a block of statements in a control structure from a loop, or even from a procedure. Suppose you have a For…….Next loop that calculates the square root of negative numbers can't be calculated ( the Sqr() function generates a runtime error,)

 
by Dinesh Thakur

Automatic memory management, also known as automatic garbage collection, is the practice of allowing the language implementation to keep track of used and unused memory, freeing the programmer from this burden.



 
by Dinesh Thakur

Command Line Arguments are parameters that are supplied to the application program at the time of invoking it for execution. We can write Java programs that can receive and use the arguments provided in the command line.



 
by Dinesh Thakur

A variable is a place in memory where we can store a value. The Java programming language defines the following kinds of variables :



 
by Dinesh Thakur

Data types are the domains which determine what type of contents can be stored in a variable. In Java, there are two types of data types:



 
by Dinesh Thakur

It is in two types. Those are,

 

1. Command line arguments

2. By using readLine() method

 
by Dinesh Thakur

Arrays:- When there is a need to use many variables then we There is a big problem because we will Conflict with name of variables So that in this Situation where we wants to Operate on many  numbers then we can use array .

 
by Dinesh Thakur

Vectors:- We know that Arrays are very useful when there is a need to use number of variables But There is a problem with Array they use only single data type or The Elements of array are always Same type For Avoiding this Problem Vectors are used.



 
by Dinesh Thakur

We know in Class data members and Members Functions are Instantiated, When Object of Class is Created New Memory is Allocated by Each Object .So for Avoiding this New Memory Each Time Creation, We Uses Static Data then data will be Common to all and the static data is used without creating an object of class Static data is used without creating an object Instead with name of class .