Tutorial :what is shared variable in java



Question:

is there any concept of shared variable in java and if it is what is it?


Solution:1

It depends on what you mean as you can "share variables" or rather "share data" in various ways. I take it that you're a beginner, so I'll make it brief. The short answer is yes, you can share variables and below are a couple of ways to do it.

Share data as arguments for parameters in functions

void funcB(int x) {      System.out.println(x);       // funcB prints out whatever it gets in its x parameter  }    void funcA() {      int myX = 123;      // declare myX and assign it with 123      funcB(myX);      // funcA calls funcB and gives it myX       // as an argument to funcB's x parameter  }    public static void main(String... args) {      funcA();  }    // Program will output: "123"  

Share data as attributes in a class

You can define a class with attributes, when you instantiate the class to an object (i.e. you "new" it) you can set the object's attributes and pass it around. Simple example is to have a parameter class:

class Point {      public int x; // this is integer attribute x      public int y; // this is integer attribute y  }  

You can use it in the following way:

private Point createPoint() {      Point p = new Point();      p.x = 1;      p.y = 2;      return p;  }    public static void main(String... args)  {      Point myP = createPoint();      System.out.println(myP.x + ", " + myP.y);  }    // Program will output: "1, 2"  


Solution:2

If you want to share variables between 2 functions, you can use global variables or pass them with pointers.

Example with pointers:

public void start() {      ArrayList a = new ArrayList();      func(a);  }    private void func(ArrayList a)  {      a.add(new Object());  }  


Solution:3

Not sure what this question means. All public classes are shared, all variables can be shared if they accessible through public methods, etc.


Solution:4

In the VB sense, a static field in Java is shared by all instances of the class.

In the classical sense, Java has various RPC, service and database access mechanisms.


Solution:5

use static keyword eg:

private static int count = 1;  public int getCount() {          return count ++;      }  

everytime u call method getCount(), count will continue +1


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