meaning of at over riding in java code example

Example 1: overriding in java

class Animal {
   public void move() {
      System.out.println("Animals can move");
   }
}

class Dog extends Animal {
   public void move() {
      System.out.println("Dogs can walk and run");
   }
}

public class TestDog {

   public static void main(String args[]) {
      Animal a = new Animal();   // Animal reference and object
      Animal b = new Dog();   // Animal reference but Dog object

      a.move();   // runs the method in Animal class
      b.move();   // runs the method in Dog class
   }
}

Example 2: method override

using method-override in your index.js
1. npm install method-override --save
2. var methodOverride = require("method-override");
3. app.use(methodOverride("_method"));
//'_method' is what methodOverride will look for
method override in your UPDATE route: 
* <form action = "/campgrounds/<%=campground._id%>/edit?_method=PUT" 
	method = "POST">
and EDIT routes: