@杰斯2009 你说的也只有第一点而已，第二点是为了让我们知道普通方法和静态方法调用同类变量时的不同，我觉得有这点会让我们思路更清晰。第三点可以知道同类中静态方法的调用可以用方法名()和类名.方法名()以及创建对象然后对象名.方法名()这三种形式来调用，不是同类只能用后两者。
2017-07-10
最新回答 / 盛夏Zzz
个人见解：Demo01 p2 = new Demo01(5.0f); //调用构造方法Demo01(float S)此时，p2.screen = 5.0 ,输出screen=5.0;然后，你给p2.screen重新赋值：p2.screen = 8.5f;是已经在上一句程序执行之后，你又重新赋值，如果楼主可以的话，试一下在这条语句之后，再重新输出一下看看现在的结果是什么。
2017-07-09
public class Initial {
public static void main(String[] args) {
Shape circle = new Circle();
circle.r = 2;
circle.getArea();
circle.getPerimeter();
Shape rectangle = new Rectangle();
rectangle.length = 2;
rectangle.width = 4;
rectangle.getArea();
rectangle.getPerimeter();
}
}
public static void main(String[] args) {
Shape circle = new Circle();
circle.r = 2;
circle.getArea();
circle.getPerimeter();
Shape rectangle = new Rectangle();
rectangle.length = 2;
rectangle.width = 4;
rectangle.getArea();
rectangle.getPerimeter();
}
}
2017-07-09
public class Rectangle extends Shape {
public void getArea() {
area = width * length;
System.out.println("矩形的面积是："+area);
}
public void getPerimeter() {
perimeter = 2 * width *length;
System.out.println("矩形的周长是："+perimeter);
}
}
public void getArea() {
area = width * length;
System.out.println("矩形的面积是："+area);
}
public void getPerimeter() {
perimeter = 2 * width *length;
System.out.println("矩形的周长是："+perimeter);
}
}
2017-07-09
public class Circle extends Shape {
public void getArea() {
// TODO Auto-generated method stub
area = pi*r*r;
System.out.println("圆的面积是："+area);
}
public void getPerimeter() {
// TODO Auto-generated method stub
perimeter = 2*pi*r;
System.out.println("圆的周长是："+perimeter);
}
}
public void getArea() {
// TODO Auto-generated method stub
area = pi*r*r;
System.out.println("圆的面积是："+area);
}
public void getPerimeter() {
// TODO Auto-generated method stub
perimeter = 2*pi*r;
System.out.println("圆的周长是："+perimeter);
}
}
2017-07-09
package wang;
public abstract class Shape {
int r;
int length;
int width;
float pi =3.14f;
double area;
double perimeter;
public abstract void getArea();
public abstract void getPerimeter();
}
public abstract class Shape {
int r;
int length;
int width;
float pi =3.14f;
double area;
double perimeter;
public abstract void getArea();
public abstract void getPerimeter();
}
2017-07-09