         1 LẬP TRINH HƯỚ NG ĐÔ ́ I TƯỢNG TRONG JAVA phần 2 IV.    A 1. Khai ba ́ o kế thư ̀ a               .   ,                                            -          (SuperClass : ) -          (SubClass)                     p cha class ClassName extends SuperClass { //Member Variables Declarations, Methods } -   ,                -                       .              ,                . 2. Viết chồ ng ha ̀ m hay che khuấ t ha ̀ m (Overriding Methods)    ,            ,                       ,           . Khi                              ( ) v     . V d :               . L toString,  .                                        2 3. Tư ̀ khoa ́ super                   .        ,         .             a      .       : - 1 :  .                       ,                cha c: classname() : super(Parameter-List) Parameter-      . super()  con : class MyPoint { int x, y; MyPoint(int x, int y) { this.x = x; this.y = y; } void display() { \ } } class MyPoint2 extends MyPoint { int z; String name; MyPoint2(int x, int y, int z, String name) { super(x,y); // Kh2  ,     this.z = z; //    this.name = name;          3 } void display() { // Vi           \ } } - 2 : : super.Member              :   () trong class MyPoint2, c: void display() { super.display(); \ } V.  , PH                                  .                             .   ,  .       ,    abs        abstract [Type] MethodName(Parameter-List) ;                         ,              .               ,  .   ,  .                                V d :      ,  ,  ,   ,               (, )  nh vi (  ,      , ).  Graphic.                       , nên              ,           ,           4 abstract class GraphicObject { int x, y; . . . void moveTo(int newX, int newY) { . . . } abstract void draw(); }          ircle,     class Circle extends GraphicObject { void draw() { . . . } } class Rectangle extends GraphicObject { void draw() { . . . } } VI.    (   ), (K      ) 1. Sư ̉ dụng tư ̀ khoa ́ final cấ m sự chồ ng lắ p                 Java,           .           ,   : class Box { double width; double height; double depth;  final double volume() {          5 return width * height * depth; } . . . } 2. Sư ̉ dụng tư ̀ khoa ́ final cấ m sự kế thư ̀ a               , .     , .                                        V d : final class Box { . . . } VII.      .         (Nested Class) : class EnclosingClass{ //      . . . static class StaticNestedClass { //       . . . } class InnerClass { //         . . . } }                .   .                 ,  . Tuy nhiên,                 . : . L (static nested class)        .                         6 bao, .  . H L (nonstatic nested class )        ,       (inner class).     . class Outer { int outer_x = 100; void test() { Inner inner = new Inner(); inner.display_x(); } class Inner { // uter int inner_y = 10; void display_x() {  } } void display_y() { // không th  } } class InnerClassDemo { public static void main(String args[]) { Outer outer = new Outer(); outer.test(); } } .          1 LẬP TRINH HƯỚ NG ĐÔ ́ I TƯỢNG TRONG JAVA phần 2 IV.    A 1. Khai ba ́ o kế thư ̀ a         .              :   () trong class MyPoint2, c: void display() { super.display(); .                 Java,           .         