java instance method code example

Example 1: instance variable java

A variable declared inside the class is called instance variable. Value of 
instance variable are instance specific.
public class InstanceVariableDemo
{
   // instance variable declared inside the class and outside the method
   int c;
   public void subtract()
   {
      int x = 100;
      int y = 50;
      c = x - y;
      System.out.println("Subtraction: " + c);
   }
   public void multiply()
   {
      int m = 10;
      int n = 5;
      c = m * n;
      System.out.println("Multiplication: " + c);
   }
   public static void main(String[] args)
   {
      InstanceVariableDemo obj = new InstanceVariableDemo();
      obj.subtract();
      obj.multiply();
   }
}

Example 2: static method vs instance method

static or class method
1) A method that is declared as static is known as the static method
2) We don't need to create the objects to call the static methods
3) Non-static (instance) members cannot be accessed in static context 
(static method, static block and static nested class) directly.
4) For example: public static int cube(int n){
return n*n*n*; (multiply *) }

Instance method
1) A method that is not declared as static is known as the instance method.
2) The object is required to call the instance method.
3) Static and non-static variables both can be accessed in instance methods.
4) For example: public void msg() {
...}.

Example 3: Explain about instanceof operator in java

An instanceof in Java is a comparison operator which, given an object instance, 
checks whether that instance is of a specified type (class/sub-class/interface) 
or not. Just like other comparison operators, it returns true or false.

Comparing any object instance with a null type through instanceof operator 
returns a false.
  
Instanceof operator is used to test the object is of which type.

Syntax : <reference expression> instanceof <destination type>
Instanceof returns true if reference expression is subtype of destination type.
Instanceof returns false if reference expression is null.