Java Tutorial

by Dinesh Thakur Category: Java Language

Identifiers in Java. A Java identifier is the symbolic name that is used for identification purpose. In Java, an identifier can be a variable name, constant name, method name, class name, array name, packages name or an interface. Few authors term variables as an identifier. For example : int score = 100;

 
by Dinesh Thakur Category: Java Language

There are times when you want to prevent inheritance. Perhaps there is no need the extensibility for various reasons. If you know this for sure, there are advantages to declaring the final keyword precisely that.

Java has a special keyword called final that can use for creating final methods, final classes, and final variables. The final modifier is void, which simply means that no value is returned.The final modifier indicates that the value of this member cannot change. We get a compile-time error if our program tries to change its contents. Each of these is explained in more detail next.

 
by Dinesh Thakur Category: Java Language

Keywords are the words. Those have specifics meaning in the compiler.

 
by Dinesh Thakur Category: Java Language

Type Casting: The process of converting one data type to another is called casting. Casting is often necessary when a function returns a data of type in different form then we need to perform an operation. Under certain circumstances Type conversion can be carried out automatically, in other cases it must be "forced" manually (explicitly). For example, the read() member function of the standard input stream (System.in) returns an int. If we want to store data of type int returned by read() into a variable of char type, we need to cast it :



 
by Dinesh Thakur Category: Java Language

New is a Keyword Which is used when we are Creating an object of class For Storing all the data like variables and member functions  of class  there is some memory Space that is to be needed So that With the help of new Keyword and Object is Instantiated or Simply an object Reserves

 
by Dinesh Thakur Category: Introduction to Java

The objects in our programs exist only while the program is executing. When the program closed, these objects cease to exist. How can we save an object in our program and restore it when the program rerun? For example, suppose that we are playing a computer chess game. We close the game before it finished. When we restart the game, it should resume from where we had left it, instead of from the beginning. One way to accomplish this would be to save information about the game (such as the locations of various game pieces, scores, and so forth) to a file, and then read this information back from the file to restore the game to the state where we had left it when it runs next. This is the idea behind serialization. Serialization is saving an object's state as a binary stream (that is, as a sequence of bytes). When an object is serialized, it is said to be flattened or deflated. The reverse process of constructing an object from the binary data is known as deserialization. Thus, a deserialised (or inflated) object is one whose state has restored.



 
by Dinesh Thakur Category: Introduction to Java

In Java 1.5, a new class known as Scanner class was introduced to simplify the task of getting input from the user. The Scanner class is in java.util package which allows the user to read the data dynamically from the keyboard. It can be used to read a File on the disk. The Java Scanner class extends Object class is present in java.lang package and implements Iterator and Closeable interfaces.



 
by Dinesh Thakur Category: Introduction to Java

Immutable class means unmodifiable or unchangeable, i.e., once the object has been created, they are immutable objects, there is no way to modify the text it represents. In Java, all primitive java.lang package wrapper classes (like String, Boolean, Byte, Short, Integer, Long, Float, Double, etc.) and String classes are immutable.



 
by Dinesh Thakur Category: Introduction to Java

In this section, we will see the implementation of a simplified version of linked list class provided by the Java library. This shows how the lists of operations manipulate the links when the list is modified.

 
by Dinesh Thakur Category: Introduction to Java

You've probably used a computer for work or leisure. Many people use computers for everyday tasks such as check the bank balance or write a school report. Computers are good for these tasks. They can treat repetitive tasks, such as adding numbers or insert words on a page without getting bored or exhausted. Computers are also good for games because they can play sequences of sounds and images, involving the human user in the process.



 
by Dinesh Thakur Category: Introduction to Java

The RMI architecture, shown in Figure, describes how remote objects behave and how parameters are passed between remote methods. Remote method invocation allows the program to define separately the behaviour and the code that implements the behaviour and allows running them on separate JVMs. This principle facilitates the clients to focus on the definition of a service while the servers can focus on providing the service.

 
by Dinesh Thakur Category: Introduction to Java

The Java RMI comes along with Java JDK l.l and higher versions. It is a true distributed computing application interface for Java. Java RMI is language-specific, and can provide more advanced features like serialization, security and so on.

 
by Dinesh Thakur Category: Introduction to Java

Applet: A small program for specific functions, which usually come with the operating system. Examples in Windows are Paint and Notepad. On a Macintosh, examples are Calculator and Scrapbook. The name comes from the term "applications" which is one variety of a software program.



 
by Dinesh Thakur Category: Introduction to Java

We will now make a small program that will input two integers in Java and display their sum. In this program, we will use the methods available in Scanner class to read data typed at keyboard and place it into variables that we specify.



 
by Dinesh Thakur Category: Introduction to Java

Our first program is composed of three logical parts :

1. Definition of the class;
2. Definition of the method main ();
3. Content of the method main ().

 
by Dinesh Thakur Category: Introduction to Java

A Java class is a group of Java objects all of which have the same or similar properties in common. Classes are logical entities and can never be physical. In a class  you may find:  
● Fields  
● Methods  
● Constructors  
● Blocks  
● Nested classes and an interface

In the Following Java Example, shows how to Create a Class Using Java Example. in this example we show that Syntax of java object creation is <className> objectName = new <classConstructor>; and the Syntax of defining methods of the java class is <modifier> <return-type> method-Name(<optionalParameterList>) <ExceptionList>



 
by Dinesh Thakur Category: Introduction to Java

In this Example we Reading amount, Year and interest in the class Scanner becomes analogous to reading string. In this example, the three numbers are read from the console, and then perform Simple Interest,Compound Interest operations and results printed on the screen in formatted output.

 
by Dinesh Thakur Category: Introduction to Java

In this Example we Reading the numbers and string in the class Scanner becomes analogous to reading string. In this example, the two numbers are read from the console, results printed on the screen formatted output.

 

Page 1 of 40



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.