Object oriented day 8:
Review:
-
Interface:
Reference data type, interface definition, can only contain constants and abstract methods
Cannot be instantiated, needs to be implemented, implementation class: all abstract methods must be overridden
A class can implement multiple interfaces, separated by commas. If it inherits and implements again, it should inherit first and then implement
Interfaces can inherit interfaces
Meaning: encapsulate the common attributes and behaviors of some derived classes -- realize multi inheritance
It is a standard and a specification
Notes:
1. Polymorphism:
Methods (behavior is method) are also polymorphic;
(1) Performance:
① When the same object is modeled into different types, it has different functions
-----Polymorphism of objects: I, you, water... All objects are polymorphic (experience tomorrow)
② Features: when a reference of the same type points to different objects, it has different implementations
-----Polymorphism of behavior: cut(), move(), getImage(), getScore() - all abstract methods are polymorphic
people p1 = new barber(); people p2 = new surgeon();
(2) Upward modeling / automatic type conversion: seaobject 0 = new Battleship();
① A reference to a supertype points to an object of a derived class
② What you can point out depends on the type of reference: P1 cut(); p2. cut();
③ There are two data types that can be modeled: superclass + implemented interface
(3) There are only two conditions for the success of forced type conversion:
① The object pointed to by the reference is the type
② Refers to the object that implements the interface or inherits the class
(4) If the above conditions are not met during forced conversion, ClassCastException type conversion exception occurs
Suggestion: before forced conversion, first judge whether the referenced object is of this type through instanceof
package ooday08;
public class MultiTypeDemo {
public static void main(String[] args){
/*
There are only two conditions for successful forced type conversion:
①The object (Boo()) pointed to by reference o is the type (Boo type)
"Data type reference type variable = new object "
Data type: Aoo Reference: refers to the object Boo from the reference type variable pointing to: equal sign = object: new
②Refers to the object that implements the interface or inherits the class
*/
Aoo o = new Boo(); //The object of o is Boo
Boo o1 = (Boo)o; //① The object to which reference o refers is of type Boo. [it is wrong to assign o to Boo, because o is Aoo. It needs to be forced to turn from large to small. Add (Boo) to the front of O]
Inter o2 = (Inter)o; //② Reference the object pointed to and implement the Inter interface
//Coo o3 = (Coo)o; //- Runtime ClassCastException type conversion exception
if(o instanceof Coo){ //false, judge first
Coo o4 = (Coo)o; //Re strong turn
}else{
System.out.println("o no Coo type");
}
/*
System.out.println(o instanceof Boo);//true
System.out.println(o instanceof Inter);//true
System.out.println(o instanceof Coo);//false
*/
}
}
interface Inter{}
class Aoo{}
class Boo extends Aoo implements Inter{}
class Coo extends Aoo{}
Supplement:
-
Interfaces can inherit multiple interfaces:
interface Inter1{ void show(); } interface Inter2{ void test(); } interface Inter3 extends Inter1,Inter2{ void say(); } -
When do I need a forced rotation?
----The attribute / behavior to be accessed does not exist in the superclass, so it must be forcibly converted. The instanceof judgment must be made before forcibly converting
-
ArrayIndexOutOfBoundsException: array subscript out of bounds exception
NullPointerException: null pointer exception
ClassCastException: type conversion exception
-
This picture will be used in operation 2. Collision between deep-water bomb and submarine:
Object oriented day 8 job:
1. Mine entry: second half
2. Collision between deep-water bomb and submarine
3. Drawing points and drawing life
1. Mine entry: the second half.. Reference code:
package cn.tedu.submarine;
import javax.swing.JFrame;
import javax.swing.JPanel; //1.
import java.awt.Graphics;
import java.util.Timer;
import java.util.TimerTask;
import java.util.Random;
import java.util.Arrays;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
/** The whole game world */
public class World extends JPanel { //2.
public static final int WIDTH = 641; /** Width of window */
public static final int HEIGHT = 479; /** Window height */
//The following pile is the objects displayed in the window
private Battleship ship = new Battleship(); //warship
private SeaObject[] submarines = {}; //Submarine (reconnaissance submarine, torpedo submarine, mine submarine) array
private Mine[] mines = {}; //Mine array
private Bomb[] bombs = {}; //Deep water bomb array
/** Generate submarine (reconnaissance submarine, torpedo submarine, mine submarine) objects */
public SeaObject nextSubmarine(){
Random rand = new Random(); //Random number object
int type = rand.nextInt(20); //0 to 19
if(type<10){ //From 0 to 9, the reconnaissance submarine object is returned
return new ObserveSubmarine();
}else if(type<15){ //10 to 14, return to the torpedo submarine object
return new TorpedoSubmarine();
}else{ //At 15 to 19, return to the mine submarine object
return new MineSubmarine();
}
}
private int subEnterIndex = 0; //Submarine admission count
/** Submarines (reconnaissance submarines, torpedo submarines and mine submarines) enter the site */
public void submarineEnterAction(){ //Walk every 10 milliseconds
subEnterIndex++; //Increase by 1 every 10 milliseconds
if(subEnterIndex%40==0) { //Walk every 400 (40 * 10) milliseconds
SeaObject obj = nextSubmarine(); //Get submarine object
submarines = Arrays.copyOf(submarines,submarines.length+1); //Capacity expansion
submarines[submarines.length-1] = obj; //Add obj to the last element of submarines
}
}
private int mineEnterIndex = 0; //Mine admission count
/** Mine entry */
public void mineEnterAction(){ //Walk every 10 milliseconds
mineEnterIndex++; //Increase by 1 every 10 milliseconds
if(mineEnterIndex%100==0){ //Walk every 1 second (100 * 10)
for(int i=0;i<submarines.length;i++){ //Traverse all submarines
if(submarines[i] instanceof MineSubmarine){ //If the submarine is a mine submarine
MineSubmarine ms = (MineSubmarine)submarines[i]; //Converting submarines to mine submarines
Mine obj = ms.shootMine(); //Acquire mine object
mines = Arrays.copyOf(mines,mines.length+1); //Capacity expansion
mines[mines.length-1] = obj; //Add obj to the last element
}
}
}
}
/** Ocean object movement */
public void moveAction(){ //Walk every 10 milliseconds
for(int i=0;i<submarines.length;i++){ //Traverse all submarines
submarines[i].move(); //Submarine movement
}
for(int i=0;i<mines.length;i++){ //Traverse all mines
mines[i].move(); //Mine movement
}
for(int i=0;i<bombs.length;i++){ //Traverse all deep-water bombs
bombs[i].move(); //Deep water bomb movement
}
}
/** Delete out of bounds ocean objects */
public void outOfBoundsAction(){ //Walk every 10 milliseconds
for(int i=0;i<submarines.length;i++){ //Traverse all submarines
if(submarines[i].isOutOfBounds()){ //It's out of bounds
submarines[i] = submarines[submarines.length-1]; //Replace the cross-border submarine with the last element
submarines = Arrays.copyOf(submarines,submarines.length-1); //Shrink volume (shrink the last element)
}
}
for(int i=0;i<mines.length;i++){ //Traverse all mines
if(mines[i].isOutOfBounds()){ //It's out of bounds
mines[i] = mines[mines.length-1]; //Replace the transboundary mine with the last element
mines = Arrays.copyOf(mines,mines.length-1); //Shrink volume (shrink the last element)
}
}
for(int i=0;i<bombs.length;i++){ //Traverse all deep-water bombs
if(bombs[i].isOutOfBounds()){ //It's out of bounds
bombs[i] = bombs[bombs.length-1]; //Replace the cross-border bomb with the last element
bombs = Arrays.copyOf(bombs,bombs.length-1); //Shrink volume (shrink the last element)
}
}
}
/** Start program execution */
public void action(){
KeyAdapter k = new KeyAdapter() { //Not required
/** Override keyReleased() key lift event */
public void keyReleased(KeyEvent e) { //When the key is lifted, it will be triggered automatically - it is not required to master
if(e.getKeyCode()==KeyEvent.VK_SPACE){ //If the space bar is raised -- it is not required to master
Bomb obj = ship.shoot(); //Get depth bomb object
bombs = Arrays.copyOf(bombs,bombs.length+1); //Capacity expansion
bombs[bombs.length-1] = obj; //Add obj to the last element of the bombs
}
if(e.getKeyCode()==KeyEvent.VK_LEFT){ //If the left button head is raised -- it is not required to master
ship.moveLeft(); //The warship moved left
}
if(e.getKeyCode()==KeyEvent.VK_RIGHT){ //If the right button head is raised -- it is not required to master
ship.moveRight(); //Warship shift right
}
}
};
this.addKeyListener(k); //Not required
Timer timer = new Timer(); //Timer Objects
int interval = 10; //Timing interval (in milliseconds)
timer.schedule(new TimerTask() {
public void run() { //Something done regularly (occurs automatically every 10 milliseconds)
submarineEnterAction(); //Submarines (reconnaissance submarines, torpedo submarines and mine submarines) enter the site
mineEnterAction(); //Mine entry
moveAction(); //Ocean object movement
outOfBoundsAction(); //Delete out of bounds ocean objects
repaint(); //Redraw (call paint() again)
}
}, interval, interval); //Timing plan
}
/** Rewrite paint() g: Brush */
public void paint(Graphics g){ //Walk every 10 milliseconds
Images.sea.paintIcon(null,g,0,0); //Draw an ocean map
ship.paintImage(g); //Painted warship
for(int i=0;i<submarines.length;i++){ //Traverse submarine array
submarines[i].paintImage(g); //Draw submarine
}
for(int i=0;i<mines.length;i++){
mines[i].paintImage(g);
}
for(int i=0;i<bombs.length;i++){
bombs[i].paintImage(g);
}
}
public static void main(String[] args) {
JFrame frame = new JFrame(); //3.
World world = new World();
world.setFocusable(true);
frame.add(world);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(WIDTH+16, HEIGHT+39);
frame.setLocationRelativeTo(null);
frame.setVisible(true); //1) Set the window visible 2) call the paint() method as soon as possible
world.action(); //Start program execution
}
}
//Note: there are no changes in other categories, which are omitted here
2. The collision between a deep-water bomb and a submarine.. Reference code:
package day08;
import javax.swing.ImageIcon;
import java.awt.Graphics;
import java.util.Random;
//Ocean object
public abstract class SeaObject {
public static final int LIVE = 0;
public static final int DEAD = 1;
protected int state = LIVE; //current state
protected int width;
protected int height;
protected int x;
protected int y;
protected int speed;
public SeaObject(int width,int height){
this.width = width;
this.height = height;
x = -width;
Random rand = new Random();
y = rand.nextInt(World.HEIGHT-height-150)+150;
speed = rand.nextInt(3)+1;
}
public SeaObject(int width,int height,int x,int y,int speed){
this.width = width;
this.height = height;
this.x = x;
this.y = y;
this.speed = speed;
}
public abstract void move();
public abstract ImageIcon getImage();
public boolean isLive(){
return state==LIVE;
}
public boolean isDead(){
return state==DEAD;
}
public void paintImage(Graphics g){
if(isLive()){
this.getImage().paintIcon(null,g,x,y);
}
}
/** Detect submarine crossing */
public boolean isOutOfBounds(){
return x>= World.WIDTH; //x> = window width, that is, it is out of bounds
}
/** Collision detection */
public boolean isHit(SeaObject other){
//Suppose this refers to a submarine and other refers to a bomb
int x1 = this.x-other.width; //x1: submarine x-bomb width
int x2 = this.x+this.width; //x2: submarine x + submarine width
int y1 = this.y-other.height; //y1: submarine y-bomb height
int y2 = this.y+this.height; //y2: submarine y + submarine height
int x = other.x; //x: Bomb x
int y = other.y; //y: Bomb y
return x>=x1 && x<=x2
&&
y>=y1 && y<=y2; //If x is between x1 and x2, and y is between y1 and y2, it means collision
}
/** Ocean objects die */
public void goDead(){
state = DEAD; //Change the status to DEAD
}
}
package day08;
import javax.swing.ImageIcon;
//warship
public class Battleship extends SeaObject {
private int life;
public Battleship(){
super(66,26,270,124,20);
life = 5;
}
public void step(){
System.out.println("Warship movement");
}
public ImageIcon getImage(){
return Images.battleship;
}
public Bomb shoot(){
return new Bomb(this.x,this.y);
}
public void moveLeft(){
x-=speed;
}
public void moveRight(){
x+=speed;
}
public void addLife(int num){
life += num;
}
}
package day08;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Graphics;
import java.util.Arrays;
import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
//The whole game world
public class World extends JPanel {
public static final int WIDTH = 641;
public static final int HEIGHT = 479;
private Battleship ship = new Battleship(); //warship
private SeaObject[] submarines = {}; //Submarine (reconnaissance submarine, torpedo submarine, mine submarine)
private Mine[] mines = {}; //mine
private Bomb[] bombs = {}; //Deep water bomb
/** Randomly generated submarine */
public SeaObject nextSubmarine(){
Random rand = new Random();
int type = rand.nextInt(20);
if(type<10){
return new ObserveSubmarine();
}else if(type<15){
return new TorpedoSubmarine();
}else{
return new MineSubmarine();
}
}
private int subEnterIndex = 0;
/** Submarine admission */
public void submarineEnterAction(){ //Walk every 10 milliseconds
subEnterIndex++;
if(subEnterIndex%40==0){ //Every 40 milliseconds
SeaObject obj = nextSubmarine();
submarines = Arrays.copyOf(submarines,submarines.length+1);
submarines[submarines.length-1] = obj;
}
}
private int mineEnterIndex = 0;
/** Mine (torpedo, mine) entry */
public void MineEnterAction(){
mineEnterIndex++;
if(mineEnterIndex%100==0){
for(int i=0;i<submarines.length;i++){
if(submarines[i] instanceof MineSubmarine){
MineSubmarine ms = (MineSubmarine)submarines[i];
Mine obj = ms.shootMine();
mines = Arrays.copyOf(mines,mines.length+1);
mines[mines.length-1] = obj;
}
}
}
}
/** Ocean object movement */
public void moveAction(){
for(int i=0;i<submarines.length;i++){
submarines[i].move();
}
for(int i=0;i<mines.length;i++){
mines[i].move();
}
for(int i=0;i<bombs.length;i++){
bombs[i].move();
}
}
/** Delete out of bounds objects */
public void outOfBoundsAction(){
for(int i=0;i<submarines.length;i++){
if(submarines[i].isOutOfBounds() || submarines[i].isDead()){
submarines[i] = submarines[submarines.length-1];
submarines = Arrays.copyOf(submarines,submarines.length-1);
}
}
for(int i=0;i<mines.length;i++){
if(mines[i].isOutOfBounds() || mines[i].isDead()){
mines[i] = mines[mines.length-1];
mines = Arrays.copyOf(mines,mines.length-1);
}
}
for(int i=0;i<bombs.length;i++){
if(bombs[i].isOutOfBounds() || bombs[i].isDead()){
bombs[i] = bombs[bombs.length-1];
bombs = Arrays.copyOf(bombs,bombs.length-1);
}
}
}
private int score = 0; //Player score
//Collision between deep-water bomb and submarine
public void bombBangAction(){
for(int i=0;i<bombs.length;i++){
Bomb b = bombs[i];
for(int j=0;j<submarines.length;j++){
SeaObject s = submarines[j];
if(b.isLive() && s.isLive() && s.isHit(b)){
b.goDead();
s.goDead();
if(s instanceof EnemyScore){
EnemyScore es = (EnemyScore)s;
score += es.getScore();
}
if(s instanceof EnemyLife){
EnemyLife ea = (EnemyLife)s;
int num = ea.getLife();
ship.addLife(num);
}
}
}
}
}
/** Start the operation of the program */
public void action(){
KeyAdapter k = new KeyAdapter(){
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_SPACE){
Bomb obj = ship.shoot(); //Deep water bomb admission
bombs = Arrays.copyOf(bombs,bombs.length+1);
bombs[bombs.length-1] = obj;
}
if(e.getKeyCode() == KeyEvent.VK_LEFT){
ship.moveLeft();
}
if(e.getKeyCode() == KeyEvent.VK_RIGHT){
ship.moveRight();
}
}
};
this.addKeyListener(k);
Timer timer = new Timer();
int interval = 10;
timer.schedule(new TimerTask() {
public void run() {
submarineEnterAction(); //Submarines (reconnaissance, mines, torpedoes) enter the site
MineEnterAction(); //Mine entry
moveAction(); //Ocean object movement
outOfBoundsAction(); //Delete out of bounds objects
bombBangAction(); //Collision between deep-water bomb and submarine
repaint();
}
}, interval, interval);
}
public void paint(Graphics g){
Images.sea.paintIcon(null,g,0,0); //Draw an ocean map
ship.paintImage(g);
for(int i=0;i<submarines.length;i++){
submarines[i].paintImage(g);
}
for(int i=0;i<mines.length;i++){
mines[i].paintImage(g);
}
for(int i=0;i<bombs.length;i++){
bombs[i].paintImage(g);
}
}
public static void main(String[] args) {
JFrame frame = new JFrame();
World world = new World();
world.setFocusable(true);
frame.add(world);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(WIDTH+16, HEIGHT+39);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
world.action();
}
}
//Note: there are no changes in other categories, which are omitted here
3. Draw points and draw life.. Reference code:
package day08;
import javax.swing.ImageIcon;
//warship
public class Battleship extends SeaObject {
private int life;
public Battleship(){
super(66,26,270,124,20);
life = 5;
}
public void step(){
System.out.println("Warship movement");
}
public ImageIcon getImage(){
return Images.battleship;
}
public Bomb shoot(){
return new Bomb(this.x,this.y);
}
public void moveLeft(){
x-=speed;
}
public void moveRight(){
x+=speed;
}
public void addLife(int num){
life += num;
}
public int getLife(){
return life;
}
}
package day08;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Graphics;
import java.util.Arrays;
import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
//The whole game world
public class World extends JPanel {
public static final int WIDTH = 641;
public static final int HEIGHT = 479;
private Battleship ship = new Battleship(); //warship
private SeaObject[] submarines = {}; //Submarine (reconnaissance submarine, torpedo submarine, mine submarine)
private Mine[] mines = {}; //mine
private Bomb[] bombs = {}; //Deep water bomb
/** Randomly generated submarine */
public SeaObject nextSubmarine(){
Random rand = new Random();
int type = rand.nextInt(20);
if(type<10){
return new ObserveSubmarine();
}else if(type<15){
return new TorpedoSubmarine();
}else{
return new MineSubmarine();
}
}
private int subEnterIndex = 0;
/** Submarine admission */
public void submarineEnterAction(){ //Walk every 10 milliseconds
subEnterIndex++;
if(subEnterIndex%40==0){ //Every 40 milliseconds
SeaObject obj = nextSubmarine();
submarines = Arrays.copyOf(submarines,submarines.length+1);
submarines[submarines.length-1] = obj;
}
}
private int mineEnterIndex = 0;
/** Mine (torpedo, mine) entry */
public void MineEnterAction(){
mineEnterIndex++;
if(mineEnterIndex%100==0){
for(int i=0;i<submarines.length;i++){
if(submarines[i] instanceof MineSubmarine){
MineSubmarine ms = (MineSubmarine)submarines[i];
Mine obj = ms.shootMine();
mines = Arrays.copyOf(mines,mines.length+1);
mines[mines.length-1] = obj;
}
}
}
}
/** Ocean object movement */
public void moveAction(){
for(int i=0;i<submarines.length;i++){
submarines[i].move();
}
for(int i=0;i<mines.length;i++){
mines[i].move();
}
for(int i=0;i<bombs.length;i++){
bombs[i].move();
}
}
/** Delete out of bounds objects */
public void outOfBoundsAction(){
for(int i=0;i<submarines.length;i++){
if(submarines[i].isOutOfBounds() || submarines[i].isDead()){
submarines[i] = submarines[submarines.length-1];
submarines = Arrays.copyOf(submarines,submarines.length-1);
}
}
for(int i=0;i<mines.length;i++){
if(mines[i].isOutOfBounds() || mines[i].isDead()){
mines[i] = mines[mines.length-1];
mines = Arrays.copyOf(mines,mines.length-1);
}
}
for(int i=0;i<bombs.length;i++){
if(bombs[i].isOutOfBounds() || bombs[i].isDead()){
bombs[i] = bombs[bombs.length-1];
bombs = Arrays.copyOf(bombs,bombs.length-1);
}
}
}
private int score = 0; //Player score
//Collision between deep-water bomb and submarine
public void bombBangAction(){
for(int i=0;i<bombs.length;i++){
Bomb b = bombs[i];
for(int j=0;j<submarines.length;j++){
SeaObject s = submarines[j];
if(b.isLive() && s.isLive() && s.isHit(b)){
b.goDead();
s.goDead();
if(s instanceof EnemyScore){
EnemyScore es = (EnemyScore)s;
score += es.getScore();
}
if(s instanceof EnemyLife){
EnemyLife ea = (EnemyLife)s;
int num = ea.getLife();
ship.addLife(num);
}
}
}
}
}
/** Start the operation of the program */
public void action(){
KeyAdapter k = new KeyAdapter(){
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_SPACE){
Bomb obj = ship.shoot(); //Deep water bomb admission
bombs = Arrays.copyOf(bombs,bombs.length+1);
bombs[bombs.length-1] = obj;
}
if(e.getKeyCode() == KeyEvent.VK_LEFT){
ship.moveLeft();
}
if(e.getKeyCode() == KeyEvent.VK_RIGHT){
ship.moveRight();
}
}
};
this.addKeyListener(k);
Timer timer = new Timer();
int interval = 10;
timer.schedule(new TimerTask() {
public void run() {
submarineEnterAction(); //Submarines (reconnaissance, mines, torpedoes) enter the site
MineEnterAction(); //Mine entry
moveAction(); //Ocean object movement
outOfBoundsAction(); //Delete out of bounds objects
bombBangAction(); //Collision between deep-water bomb and submarine
repaint();
}
}, interval, interval);
}
public void paint(Graphics g){
Images.sea.paintIcon(null,g,0,0); //Draw an ocean map
ship.paintImage(g);
for(int i=0;i<submarines.length;i++){
submarines[i].paintImage(g);
}
for(int i=0;i<mines.length;i++){
mines[i].paintImage(g);
}
for(int i=0;i<bombs.length;i++){
bombs[i].paintImage(g);
}
g.drawString("SCORE: "+score,200,50);
g.drawString("LIFE: "+ship.getLife(),400,50);
}
public static void main(String[] args) {
JFrame frame = new JFrame();
World world = new World();
world.setFocusable(true);
frame.add(world);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(WIDTH+16, HEIGHT+39);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
world.action();
}
}
//Note: there are no changes in other categories, which are omitted here