About Static and instance Method

public class SecondClass
{
int i;
public int sum()
{
int i=5;
return i+this.i;
}
}
---------------------
public class FirstClass
{
public static void main(String args[])
{
SecondClass m=new SecondClass();
m.i=7;
System.out.println("Sum="+m.sum());
}
}

----------------------------

Output:

Sum=12

=============================

public class SecondClass
{
int i;
 public static int sum()
{
int i=5;
return i;
}
}
---------------------
public class FirstClass
{
public static void main(String args[])
{
 SecondClass m=new SecondClass();
 m.i=7;
 System.out.println("Sum="+m.sum());
}
}

static methods are  very far from object instance.that are totaly link to a class.
an another point that static methods can never user non-static members.