Class X (ICSE) Variables and Comments

CLASS - X (ICSE)

COMPUTER  APPLICATION

Variables

®     A named memory location, whose contains can be changed with in program execution is known as variable.

®     It is a combination of "vary + able" that means its value can be changed.

®     When you run any program, it consumes memory in RAM till its execution in process.

®     Examples:

Ø  int counter;

Ø  double temp;

Ø  String name;

Ø  int[] ages;

Ø  char letters[]

®     String is a predefined class not a primitive data type.

Types of Variable

There are three types of variables in java

1.      local variable

2.      instance variable

3.      static variable

1) Local Variable

®     A variable which is declared inside the method is called local variable.

2) Instance Variable or Object Variable

®     A variable which is declared inside the class but outside the method is called instance variable.

®     It is  not declared as static.

3) Static variable or Class Variable

®     A variable that is declared as static is called static variable.

®     It cannot be local.

    Example of types of variables

class TypesOfVariables{    

    

    int data=50;                                  //instance variable 

    static int m=100;                         //static variable 

    void method(){ 

    int n=90;                                     //local variable 

    } 

 }

Comments

1.     Block or multiple-line comment:

®     Begin with /* and terminate with */ that spans multiple lines.

2.     Line comment:

®     Begin with // and terminate at the end of the line.

3.     Documentation comment:

®     Begin with /** and terminate with */ that spans multiple lines.

®     They are generally created using the automatic documentation generation tool