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Variables in java

Tuesday, 29 May 2012

Variables: There can be three types of variables in java.

      1. Instance Variables : These are Non-Static Fields. Individual states of objects are stored in Instance variables. These
        are declared without the static keyword. For number of objects created from a class all objects use same copy of instance
        variable. 

    Example:

import java.io.*;

class Student{

   // this instance variable is visible for any child class.

   public String name;  

   // percentage variable is visible in Student class only.

   private double percentage;  

   // The name variable is assigned in the constructor.

   public Student (String StudName){

      name = StudName;

   }

   // The percentage variable is assigned a value.

   public void setPercentage(double StudPercent){

      percentage = StudPercent;

   }  

   // This method prints the Student details.

   public void PrintStudentDetails(){

      System.out.println("name  : " + name );

      System.out.println("Percentage :" + percentage);

   }

   public static void main(String args[]){

      Student S1 = new Student("karana");

      S1.setPercentage(14.32);

      S1.PrintStudentDetails();

   }

}



      2.Class Variables : These are Static Fields. These are declared using static modifier. There will be only one copy of each
        class variable per class for all the objects created from that class. 

import java.io.*;

class Student{

   // marks  variable is a private static variable

   private static int marks;

   // Course is a constant

   public static final String Course = "IT";

   public static void main(String args[]){

      marks = 36;

      System.out.println(Course +"marks:"+marks);

   }

}

      3. Local Variables : The syntax for declaring a local variable is similar to declaring a field (for example, int count = 0;).
        These are created when a method, block or constructors are entered and destroyed when it exits. There are no default
        vales for local variables and internally these are maintained at stack level.

public class LocalVar{

   public void GetTotal(){

      int total = 0;

      total = total + 3;

      System.out.println("Total is : " + total)

   }  

   public static void main(String args[]){

      LocalVar L1 = new LocalVar();

      L1.GetTotal();

   }

}

 

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