History of Java Program


Java is pure object-oriented programming language design and developed by sun microsystems in early 1990’s. It is used to write software for electronics device’s as well as perform internet computing. Now a day sun microsystems have been taken by Oracle Corporation.

History of Java Program

In early 1990’s Sun Microsystems came with a concept of developing the software for electronics devices. They have developed a team called as Senlth team or green projects team under the leadership James Goslin, Piter Not trick, Eduline etc.
They have decided to develop the software from electronics camera. The design was started and it was decided to write the code in c language. When the design was completed then they know the code could not be written using c. Now they have decided to developed a newer language for it. And this language was called as “Oak“.

They have tested the oak for different devices and it was successful. Now the oak was commercialised to developed the software. During the Commercialization, the copywrites case was a field to use the name oak. The sun microsystems have settled the case outside the court by retaining the name of the language. After it, they have made and renamed with two operating systems developing company to write the operating system such that the oak program can be established directly without making any modification and the language is called as Java. Its logo is a coffee cup.

Features and Characteristics of Java Program

The Java languages provide the following features.

1) Object-oriented: Java is a pure object-oriented programming language that is all the code are written in class.

2) Class:- It is the blocks in which all the code are written. It contains both the variable and the function.

3) Object:- It is the variable of the class in which all the members of the class are created physically in continuous order.

4) Encapsulation:- It is the process of wrapping the code such that the internal mechanism is not visible to an outsider.

5) Data hiding:- It is the process of an accessing of the data by the outsider code.

6) Inheritance:- Inheritance is the mechanism of the previously defines code by the newer code.

7) Polymorphism:- It is the mechanism of defining multiple properties with the same name. Such that each may be performing same or different types of task.

8) Abstraction:- It is the process of providing different implications for the same name is called as an abstraction.

9) Message passing:- It is the process of communicating one object with the another.

10) Portable:- Java is portable is nature that is once developed it can be executed on any types of a machine without modification.

11) Platform independent:- Java is platform independent that is Java program once developed in any operating system can be executed in any other operations system without modification.

12) Architecture neutral:- Java is architecture neutral that is a program written in one type of microprocessor can we executed on any other type of microprocessor.

13) Simple:- Java is simple to learn and use.

14) Secure:- Java is 100% secure that is only authorised users can access it.

15) Compile and interpreted:- Java program is both compile and interpreted. The compiler is used to convert source code into machine code and interpreter is used for executing the Java program.

16) Multithreading:- Java allows to execute multiple parts of the same program in parallels.

17) Exception handling:- It is the mechanism of monitoring and handling the runtime error.

18) Database connectivity:- Java allows connecting with almost all RDBMS to store the data on a permanent basis.

Variable:- It is the location of the memory used to store the data that can be modified during the execution of the program.

Use of variable name:-

There are a various variable name

  1. Always start with an alphabet.
  2. Digit may be used but the first letter is an alphabet.
  3. A special symbol is not allowed in the variable name.
  4. A keyword is not allowed as a variable name.
  5. Blank spaces are not allowed in the variable name.
  6. Uppercase and lowercase name are different.
  7. A maximum length of the variable name is up to 255 character.
  8. If a variable name is multi-word string them the first letter of next word must be in upper case.

Constant:- Its value cannot be modified once provided.


final <data type><constant name>=value

Here final is the keyword of Java use to create the constant.


final int a=10

Operator:- Operator in the symbol use perform the calculation.

  • Operand
  • Calculation

Operand :-

  1. Unary
  2. Binary
  3. Ternary


  1. Arthmetical (+, -, *, %)
  2. Relational (>, <, >=, <=,!=, ==)
  3. Logical (&&, ||, !)
  4. Assignment (=)
  5. Increment (+ +)
  6. Decrement (- -)
  7. Bitwise (&, !!, ^, >>, <<, >>>, <<<)
  8. Special (•, new)

Java identifiers

Identifiers : Identifiers are the name given to the variable constant array method class etc. Java provide specialised rule for different identifiers for these naming.
Java token:- Java token is the collection of variable, constant, data type, operator, expression, keywords, input-output statement etc. They are the building blocks of Java program that is used to develop the Java code and program.
Expression:- Expression is the collection of operator and operand that is used to perform different types of calculation and perform different types of calculation and processing.

There are two type of expression
1) Operator used
2) Technique

Operator used In Java:-

a) Arithmetical expression
b) Relational expression
c) Logical expression
d) Mixed expression

Arithmetical expression:- Expression having only arithmetical operator is called as an arithmetical expression
a + b, a * b * c etc.

Relational expression:- Expression having only relational operator is called a relational expression.
a > b, a < b, a = b etc.

Logical expression:- Expression having only logical operators is called a logical expression.
a && b, a|| b

Mixed expression:- Expression having different types of an operator is called as a mixed expression.
a + b > c, a – b > c && d < f etc.

a) Simple expression
b) Compound expression

Simple expression:- Expression in which all the statement are independent of one another is called as a simple expression.
a = b + c, d = m * n, g = h / k

Compound expression:- Expression in which one or more statement depends on a particular statement is called as a compound expression. It is also called as a block. It is always written the braces {}.
a = b + c
d = m * n
g = h / k

Precedence of the operator:- In Java there are multiple types of an operator and in each type, there are multiple numbers of the operator. Then it is necessary to inform the weights to the operator called as precedence or priority. Priority specified the order in which operator will be evaluated. Higher precedence operator is evaluated first and lower precedence operator is evaluated after it.

Precedence level is as:-
1) Arithmetical
a) *, /, %
b) +, –
2) Relational
>, <, >=, <=, !=, ==
3) Logical
!, &&, ||

a) Higher precedence operator will be evaluated first and lower precedence operator will be evaluated after it.
b) If multiple operators of the same precedence come them they must be evaluated from left to right.
c) To change the precedence of the operator we use parathesis (U);
2 + 3 * 5 ( 2 + 3 ) * 5
2 + 15 5 * 5
17 25


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