AIDE_JAVA教程答案_第十七课(方法)

第十七课,学习定义方法。一个对象包含3种最常见的成员:构造器(参考上一课)、数据和方法。数据用于定义状态,而方法是行为特征的抽象。看看这个程序,该Rectangle类有width字段和height字段以及构造函数,在main()方法中创建一个对象rect。

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
}

我们在Rectangle类中增加方法getWidth(),该方法返回width字段的值。

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// The method
	int getWidth()
	{
		return this.width;
	}
}

在main()方法中通过创建Rectangle对象对getWidth()方法进行调用,该对象被隐含地作为参数传递,在getWidth()方法中可以通过关键字this访问。

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// The method
	int getWidth()
	{
		return this.width;
	}
}

现在,添加一个方法getHeight(),返回矩形的高度。

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// The method
	int getWidth()
	{
		return this.width;
	}
    
    int getHeight(){
        return this.height;
    }
}

在main()方法中调用getHeight()方法并打印结果。

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// The method
	int getWidth()
	{
		return this.width;
	}
    
    int getHeight(){
        return this.height;
    }
}

添加方法getArea()计算并返回矩形区域面积。

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// The method
	int getWidth()
	{
		return this.width;
	}
    
    int getHeight(){
        return this.height;
    }
    
    int getArea(){
        return this.width*this.height;
    }
}

在main()方法中调用getArea()方法并打印结果。

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
        System.out.println(rect.getArea());
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// The method
	int getWidth()
	{
		return this.width;
	}
    
    int getHeight(){
        return this.height;
    }
    
    int getArea(){
        return this.width*this.height;
    }
}

检查下面的方法void setWidth(int width),它设置一个Rectangle对象

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
		System.out.println(rect.getArea());
		
		rect.setWidth(10);
		System.out.println(rect.getArea());
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// A setter method
	void setWidth(int width)
	{
		this.width = width;
	}
	
	int getWidth()
	{
		return this.width;
	}
	
	int getHeight()
	{
		return this.height;
	}
	
	int getArea()
	{
		return this.width * this.height;
	}
}

在main()方法中,我们以10作为参数调用setWidth()方法

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
		System.out.println(rect.getArea());
		
		rect.setWidth(10);
		System.out.println(rect.getArea());
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
	// A setter method
	void setWidth(int width)
	{
		this.width = width;
	}
	
	int getWidth()
	{
		return this.width;
	}
	
	int getHeight()
	{
		return this.height;
	}
	
	int getArea()
	{
		return this.width * this.height;
	}
}

现在添加方法setHeight(),设置矩形的高度

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
		System.out.println(rect.getArea());
		
		rect.setWidth(10);
		rect.setHeight(20);
		System.out.println(rect.getArea());
		
		
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
	
    void setHeight(int height){
        this.height=height;
    }
	void setWidth(int width)
	{
		this.width = width;
	}
	
	int getWidth()
	{
		return this.width;
	}
	
	int getHeight()
	{
		return this.height;
	}
	
	int getArea()
	{
		return this.width * this.height;
	}
}

添加方法void scale(int factor),通过参数factor对矩形进行等比例缩放

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
		System.out.println(rect.getArea());
		
		rect.setWidth(10);
		rect.setHeight(20);
		System.out.println(rect.getArea());
		
		
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
    
    void scale(int factor){
        this.width=this.width*factor;
        this.height=this.height*factor;
    }
	
    void setHeight(int height){
        this.height=height;
    }
	void setWidth(int width)
	{
		this.width = width;
	}
	
	int getWidth()
	{
		return this.width;
	}
	
	int getHeight()
	{
		return this.height;
	}
	
	int getArea()
	{
		return this.width * this.height;
	}
}

在main()方法中调用rect的scale()方法,以10作为比例因子,然后打印矩形的面积

public class Main
{
	public static void main(String[] args)
	{
		Rectangle rect = new Rectangle(100, 200);
		System.out.println(rect.getWidth());
		System.out.println(rect.getHeight());
		System.out.println(rect.getArea());
		
		rect.setWidth(10);
		rect.setHeight(20);
		System.out.println(rect.getArea());
		
		rect.scale(10);
        System.out.println(rect.getArea());
	}
}

class Rectangle
{
	int width;
	int height;
	
	Rectangle(int width, int height) 
	{
		this.width = width;
		this.height = height;
	}
    
    void scale(int factor){
        this.width=this.width*factor;
        this.height=this.height*factor;
    }
	
    void setHeight(int height){
        this.height=height;
    }
	void setWidth(int width)
	{
		this.width = width;
	}
	
	int getWidth()
	{
		return this.width;
	}
	
	int getHeight()
	{
		return this.height;
	}
	
	int getArea()
	{
		return this.width * this.height;
	}
}

 

版权声明:本文为AIDE教程网原创文章,转载请附上原文出处链接和本声明。
本文链接:https://www.aidemx.cn/1591.html

版权声明:本文为AIDE教程网原创文章,转载请附上原文出处链接和本声明
本文链接: https://www.aidemx.cn/1591.html

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