What is local member and class variable

What is local member and class variable

Answer : Java variable is basically use as unit of storage in program. A variable is defined by the combination of type, identifier and an optional initializer. When we define the variables the they all have a scope, which defines their visibility, and a lifetime.

Local variable : In java local variable is a variable that is given local scope. Only the method where the parameter appears can access these variables. These variables are used to store intermediate results. Please see example below:

public class LocalVariableScope {

	public static void main(String[] args) {

	int x; // known to all code within main
	x = 10;
	if (x == 10) { // start new scope
		int y = 20; // known only to this block
		// x and y both known here.
		System.out.println("x and y: " + x + " " + y);
		x = y * 2;
	}
	// y = 100; // Error! y not known here
	// x is still known here.
	System.out.println("x is " + x);

	}

}

Output:

instance variable (Member variable) : In java an instance variable is a variable defined inside a class (i.e. a member variable), for which each object of the class has a separate copy, or instance. For see example below:

public class InstatnceVariable {

	// member variable - a new instance
	// of this variable will be created for each
	// new instance of InstatnceVariable class.
	// The lifespan of this variable is equal
	// to the lifespan of "this" instance of InstatnceVariable.
	int i;

}

Static variable (Class variable) : Static member also called class member and to create it precede its declaration with the keyword static.When a member is declared static, it can be accessed before any objects of its class are created and without reference to any object. Good example of a static member is main( ). main( ) is declared as static because it must be called before any objects exist. Instance declared as static are also callled global variables When objects of class are created no copy of a static variable is made. Instead, all instances of the class share the same static variable. Please see example below:

package com.javahonk.staticTest;

public class StaticVariableTest {

    static int a = 20;
    static int b;

    static void methodStaticForTest(int x) {
	System.out.println("x = " + x);
	System.out.println("a = " + a);
	System.out.println("b = " + b);
    }

    static {
	System.out.println("Static block initialized.");
	b = a * 5;
    }

    public static void main(String[] args) {
	methodStaticForTest(10);

    }

}

Output: