Question

java的构造方法

声明一个矩形类Rectangle,其中有多个构造方法。用不同的构造方法创建对象，并输出矩形的周长和面积。
我想尽快要这份程序，希望人才们给做份答案，本人先谢谢了

Answer 1

可以运行，源代码如下：
public class Rectangle
{
private double length;
private double width;

public Rectangle()
{

}

public Rectangle(double length, double width)
{
this.length=length;
this.width=width;
}

public void setLength(double length)
{
this.length=length;
}
public double getLength()
{
return length;
}

public void setWidth(double width)
{
this.width=width;
}
public double getWidth()
{
return width;
}

public String getValue()
{
String str="长方形的面积为:"+getLength()*getWidth()+";周长为："+2*(getLength()+getWidth())+";";
return str;
}

public static void main(String[] args)
{
Rectangle r1=new Rectangle(2.0,3.0);
System.out.println(r1.getValue());
Rectangle r2=new Rectangle();
r2.setLength(4.0);
r2.setWidth(2.0);
System.out.println(r2.getValue());
}
}

Answer 2

两个构造方法就够了把...
一个是无参构造：
public Rectangle(){}
另一个是有参构造：
public Rectangle(int height, int width){
System.out.println("矩形的周长是：" + (height + width) * 2) ;
System.out.println("矩形的面积是：" + height * width) ;
}

你创建对象的时候传入不同参数就行了...

Answer 3

public class Rectangle {

private int girth = 0;
private int space = 0;
private int length = 0;
private int width = 0;

public Rectangle()
{
this.length = 3;
this.width = 4;
}
public Rectangle(int length,int width)
{
this.length = length ;
this.width = width ;
}

public int calGirth()
{
return 2*(length+width);
}
public int calSpace()
{
return length*width;
}

public static void main(String args[])
{
Rectangle tRectangle = new Rectangle();
System.out.println("调用构造方法Rectangle()的到的周长和面积分别为："+tRectangle.calGirth()+","+tRectangle.calSpace());
Rectangle mRectangle = new Rectangle(3,4);
System.out.println("调用构造方法Rectangle(int length,int width)的到的周长和面积分别为："+mRectangle.calGirth()+","+mRectangle.calSpace());
}
}