图形形状
package day0803;
import java.util.Random;
import java.util.Scanner;
public class Test1 {
public static void main(String[] args) {
System.out.println("按回车继续");
while(true)
{
int i = new Random().nextInt(4);
switch (i)
{
case 0: f(new Shape());break;
case 1: f(new Line());break;
case 2: f(new Square());break;
case 3: f(new Circle());break;
}
}
}
private static void f(Shape o) {
o.draw();
//对line类型特殊处理
if(o instanceof Line)
{
Line l = (Line) o;
l.length();
}
new Scanner(System.in).nextLine();
o.clear();
}
}
package day0803;
public class Shape {
public void draw()
{
System.out.println("图形形状");
}
public void clear()
{
System.out.println("\n\n\n\n\n\n\n\n");
}
}
package day0803;
public class Line extends Shape {
@Override
public void draw()
{
System.out.println("-");
}
public void length()
{
System.out.println("线段的长度");
}
}
package day0803;
public class Square extends Shape {
@Override
public void draw() {
System.out.println("▲");
}
}
package day0803;
public class Circle extends Shape {
@Override
public void draw() {
System.out.println("O");
}
}
什么是面向对象
封装/继承/多态
抽象类
没有写完的类,半成品类
抽象类不能创建对象
抽象方法:只有方法定义没有方法体
Abstract
抽象方法的作用:
作为通用方法,在父类中定义
要求具体子类,必须实现这个方法
猜游戏
已经随机产生了5个不重复的大写字符
猜这5个字母
package day0804;
import java.util.Scanner;
public class Test1 {
public static void main(String[] args) {
System.out.println("1.猜数字");
System.out.println("2.猜字母");
System.out.print("选择:");
int i = new Scanner(System.in).nextInt();
GuessGame game;
if(i == 1) game = new GuessNumberGame();
else game = new GuessLetterGame();
game.start();
}
}
package day0804;
import java.util.Scanner;
abstract public class GuessGame {
public void start()
{
String r = suiji();
tishi();
while (true)
{
System.out.print("猜:");
String s = new Scanner(System.in).nextLine();
String result = bijiao(r,s);
System.out.println(result);
if(caidui(result)) break;
}
}
public abstract String suiji();
public abstract void tishi();
public abstract String bijiao(String a,String b);
public abstract boolean caidui(String result);
}
package day0804;
import java.util.Random;
public class GuessNumberGame extends GuessGame {
@Override
public String suiji() {
int r = 1 + new Random().nextInt(1000);
return String.valueOf(r);
}
@Override
public void tishi() {
System.out.println("已经随机产生了一个[1,1001)范围内的数字");
}
@Override
public String bijiao(String a, String b) {
//字符串解析为int
int intA = Integer.parseInt(a);
int intB = Integer.parseInt(b);
if(intA>intB) return "小";
else if(intA < intB) return "大";
else return "对";
}
@Override
public boolean caidui(String result) {
return result.equals("对");
}
}
package day0804;
public class GuessLetterGame extends GuessGame {
@Override
public String suiji() {
return null;
}
@Override
public void tishi() {
System.out.println("已经产生了5个不同的大写字母");
}
@Override
public String bijiao(String a, String b) {
return null;
}
@Override
public boolean caidui(String result) {
return result.equals("5A0B");
}
}