作者主页:海拥
作者简介:CSDN全栈领域优质创作者、HDZ核心组成员、蝉联C站周榜前十
抽象类 vs 接口
import java.io.*;
abstract class Shape {
String objectName = " ";
Shape(String name) { this.objectName = name;
}
public void moveTo(int x, int y){
System.out.println(this.objectName + " "
+ "已移至"
+ " x = " + x + " and y = " + y);
}
abstract public double area();
abstract public void draw();
}
class Rectangle extends Shape {
int length, width;
Rectangle(int length, int width, String name){
super(name);
this.length = length;
this.width = width;
}
@Override public void draw(){
System.out.println("矩形已绘制");
}
@Override public double area(){
return (double)(length * width);
}
}
class Circle extends Shape {
double pi = 3.14;
int radius;
Circle(int radius, String name){
super(name);
this.radius = radius;
}
@Override public void draw(){
System.out.println("圆形已绘制");
}
@Override public double area(){
return (double)((pi * radius * radius) / 2);
}
}
class HY {
public static void main(String[] args){
Shape rect = new Rectangle(2, 3, "Rectangle");
System.out.println("矩形面积:"
+ rect.area());
rect.moveTo(1, 2);
System.out.println(" ");
Shape circle = new Circle(2, "Circle");
System.out.println("圆的面积:"
+ circle.area());
circle.moveTo(2, 4);
}
}
输出
矩形面积:6.0
矩形已移至 x = 1 和 y = 2
圆的面积:6.28
圆已移至 x = 2 和 y = 4
如果您在矩形和圆形之间没有任何通用代码,请使用界面。
import java.io.*;
interface Shape {
void draw();
double area();
}
class Rectangle implements Shape {
int length, width;
Rectangle(int length, int width){
this.length = length;
this.width = width;
}
@Override public void draw(){
System.out.println("矩形已绘制");
}
@Override public double area(){
return (double)(length * width);
}
}
class Circle implements Shape {
double pi = 3.14;
int radius;
Circle(int radius) { this.radius = radius; }
@Override public void draw(){
System.out.println("圆形已绘制");
}
@Override public double area(){
return (double)((pi * radius * radius) / 2);
}
}
class HY {
public static void main(String[] args){
Shape rect = new Rectangle(2, 3);
System.out.println("矩形面积:"
+ rect.area());
Shape circle = new Circle(2);
System.out.println("圆的面积:"
+ circle.area());
}
}
输出
矩形面积:6.0
圆的面积:6.28
什么时候用什么?
如果以下任何陈述适用于您的情况,请考虑使用抽象类:
如果以下任何陈述适用于您的情况,请考虑使用接口: