Java Tutorial

by Dinesh Thakur Category: Java Evolution

All the Previous Languages are Structured or we can say that they were procedural programming means in them processing is to be done in sequence manner and These are also called the Top down or either they were bottom up Languages Most Important things those must be in the Languages are Reliability, Maintainability and Reusability and user Friendly So For Achieving these things they Developed java.



 
by Dinesh Thakur Category: Java Evolution

1) Compiled and Interpreter: has both Compiled and Interpreter Feature Program of java is First Compiled and Then it is must to Interpret it .First of all The Program of java is Compiled then after Compilation it creates Bytes Codes rather than Machine Language.



 
by Dinesh Thakur Category: Java Evolution

Language: C is a powerful, efficient, general purpose structured programming language. Although C is a high level language but it also supports features of a low level language, so it is sometimes called a middle level language. It is actually binding the gap between a machine language and more conventional high level languages. c++ is partial copy of object oriented programming language that allow programmers to build large and complex applications in a useful and efficient way.

 
by Dinesh Thakur Category: Java Evolution

C++ and Java both are Object Oriented Languages but some of the features of both languages are different from each other. Some of these features are :

 
by Dinesh Thakur Category: Java Evolution

What is JVM (Java Virtual Machine): Most programming languages such as C/C++ compile source code directly into machine code suitable for execution on a particular microprocessor architecture or operating systems such as Windows or Unix. This property does not make these languages' architecturally neutral'. However, Java is an architectural neutral language as it follows. Write once execute anywhere approach. This feature of Java achieved as the Java compiler does not translate the source code into the machine language of the computer that the program is running on. Instead, the compiler translates source code into bytecode which is not understood by the underlying operating system. So an application is needed that can convert this bytecode into machine code understood by the underlying operating system. It is accomplished using the Java Virtual Machine.



 
by Dinesh Thakur Category: Java Evolution

The JRE is the smallest set of executables and files that constitute the standard java plot form.The Java Runtime Environment (JRE) provides the libraries, the Java Virtual Machine, and other components to run applets and applications written in the Java programming language. In addition, two key deployment technologies are part of the JRE:



 
by Dinesh Thakur Category: Java Evolution

History of Java: At first glance, it may appear that Java was developed specifically for the World Wide Web. However, interestingly enough, Java was developed independently of the web, and went through several stages of metamorphosis before reaching its current status of programming language for the World Wide Web. Below is a brief history of Java.

 
by Dinesh Thakur Category: Data Type

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 Category: Data Type

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 Category: Data Type

Java has a wide variety of data types from which we can choose the suitable for a particular purpose. To operate on variables from two different types of data we have to convert Both types to the same.



 
by Dinesh Thakur Category: Data Type

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 Category: Data Type

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 Category: Data Type

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 Category: Data Type

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 Category: Data Type

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 Category: Data Type

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 Category: Data Type

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 Category: Data Type

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 Category: Data Type

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 Category: Data Type

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.



 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.