1. CLASS DEFINITION (FIELDS)
public class Point {
public int x;
public int y; }
Point p1 = new Point(); // currently x = 0, y = 0
Point p2 = new Point(); // currently x = 0, y = 0
p1.x = 16;
p1.y = 32;
p2.x = 25;
p2.y = 50;
System.out.println("(" + p1.x + ", " + p1.y + ")"); // (16, 32) System.out.println("(" + p2.x + ", " + p2.y + ")"); // (25, 50)
Again, every instance has a distinct copy of fields

2. CLASS DEFINITION (FIELDS)
package java.util;
public class Point {
int x; // Is protected by default (can only be read by java.util.*) int y; // Is protected by default (can only be read by java.util.*) }
// Meanwhile, in another package
package edu.just.cpe.MyNeatProject;
Point p1 = new Point();
Point p2 = new Point();
p1.x = 16; // NOP. Compile error.
p1.y = 32; // NOP. Compile error.
p2.x = 25; // NOP. Compile error.
p2.y = 50; // NOP. Compile error.
System.out.println("(" + p1.x + ", " + p1.y + ")"); // ERROR. System.out.println("(" + p2.x + ", " + p2.y + ")"); // ERROR.
Non-private fields can be read from an instance outside of the defining class, at a program point with field access

3. Constructors When you say new you allocate space for an object’s data.
The result is an instance of your class, which has a unique personal copy of variables and shares the same behaviors (methods)
-Implicitly, this also calls the class’s constructor

4. CLASS DEFINITION (CONSTRUCTOR)
public class Point {
private int x;
private int y;
public Point(int mx, int my) {
x = mx; // assign parameter to field
y = my; // assign parameter to field }
Point p1 = new Point(3, 4); // currently, x = 3, y = 4
Point p2 = new Point(4, 8); // currently, x = 4, y = 8
Point p3; // p3 = null, no object constructed
Constructors are special methods which are invoked after object creation (after new)
By the time the constructor executes, the fields already have their default values (never uninitialized)