feat: Add notes on static keyword usage and restrictions in Java

WHAT the doc covers:
- **Purpose of static**:
  - Used for memory management by creating class-level members.
  - Belongs to the class itself, not tied to any particular object instance.
  - Shared across all instances, reducing redundant copies of data.

- **Where static can be applied**:
  - Methods → can be called without creating an object.
  - Blocks → executed once during class loading for initialization.
  - Nested classes → static nested classes don’t need an outer class instance.

- **Restrictions of static methods**:
  - Cannot access non-static (instance) variables or methods directly, since they belong to objects.
  - Cannot use `this` or `super`, because no specific object context exists in a static context.
  - Can only:
    - Access static members directly.
    - Work with non-static members if an object reference is explicitly provided.

- **Concept summary**:
  - Static members are directly attached to the class itself.
  - Useful for utility functions, constants, shared resources, and singleton implementations.

WHY this matters:
- Clarifies why static is critical for efficient memory usage and consistent shared state.
- Helps avoid common beginner mistakes (e.g., trying to use `this` in a static method).
- Prepares for designing utility classes (`Math`, `Collections`) and managing application-wide data.

Short key: java static keyword memory-management restrictions no-this-or-super.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section16StaticFinal/src/StaticByED.java

@@ -1,19 +1,8 @@
-//It is used for memory management.
-//It can applied on methods, blocks, and nested classes.
-//main concpt behind static is that it belongs to the class rather than instances of the class.
-
-//Static method can not use non-static data members or call non-static method directly.
-
-//this and super cannot be used here.
-//Static is Direct attached to class.
-
 public class StaticByED {
-
     public static int count =0; //Count kar raha hai StaticByED
-    //My aim is not access via instance, but Access via Class. Goal Class se directly access karna hai.
+    //My aim is not access via instance, but Access via Class. Goal Class se directly accesses karna hai.
 
-    public StaticByED()
-    {
+    public StaticByED() {
         count++;
     }
 
@@ -48,20 +37,17 @@ private void setName(String name) {
         Name = name;
     }
 
-    public static void getCount()
-    {
+    public static void getCount() {
         System.out.println("Total conunts: " + count);
     }
 
-    public static void main(String[] args)
-    {
+    public static void main(String[] args) {
        /*
        Classs ka Object bana kar access kar pa raha hu.
 
        StaticByED ED = new StaticByED();
        ED.setAge(14);
        System.out.println(ED.Age);
-
        */
 
         StaticByED ED = new StaticByED();
@@ -72,4 +58,15 @@ public static void main(String[] args)
 
         StaticByED.getCount();
     }
-}
+}
+
+/*
+It is used for memory management.
+It can apply on methods, blocks, and nested classes.
+the main concept behind static is that it belongs to the class rather than instances of the class.
+
+Static methods cannot use non-static data members or call non-static method directly.
+
+this and supper cannot be used here.
+Static is Direct attached to class.
+*/