java之 ------ 类的封装、继承和多态（四）

问题：

声明颜色类Color。一种颜色由（红、绿、蓝）三元色值组成，称为RGB值。一个int整数可表示一种颜色，结构为：最高字节全1，其后3字节分别存储“红、绿、蓝”单色值，单色值范围是0～255。例如，0xff00ff00表示绿色，RGB值为(0,255,0)。

声明Color颜色类

RGB颜色值说明见教材实验3，RGB整数结构如图3.4所示，常用颜色及其RGB值如表3-1所示。

图1.1 颜色RGB整数结构图

表1-1 颜色及其RGB值

Color颜色类主要成员声明如下，再声明表示红、绿、蓝、黑、白等颜色的常量。

public class Color {                           //颜色类
    private int value;                         //颜色值

    public Color(int red, int green, int blue)       //以三元色构造颜色对象
    public Color(int rgb)                      //以三元色构造颜色对象
    public int getRGB()                      //返回颜色对象的RGB值
    public int getRed()                       //返回颜色对象的红色值
    public int getGreen()                     //返回颜色对象的绿色值
    public int getBlue()                      //返回颜色对象的蓝色值
    public String toString()                   //返回颜色对象的字符串描述
}

代码实现：

import java.util.*;
public class Color{
	private int value;
	int red,green,blue;
	public Color(int red,int green,int blue){
		this.set(red,green,blue);
		this.value=blue+(green<<8)+(red<<16)+(255<<24);
	}
	public Color(int rgb){
		this.value=rgb;
		this.set(rgb);
	}
	public void set(int rgb){
		this.blue=this.value&255;
		this.green=(this.value&(255<<8))>>8;
		this.red=(this.value&(255<<16))>>16;
	}
	public void set(int red,int green,int blue){
		this.red=red;
		this.green=green;
		this.blue=blue;
	}
	public String getRGB(){
		return Integer.toHexString(this.value);
	}
	public int getRed(){
		return this.red;
	}
	public int getGreen(){
		return this.green;
	}
	public int getBlue(){
		return this.blue;
	}
	public String toString(){
		return "( red , green , blue ) === ( "+this.red+" , "+this.green+" , "+this.blue+" )";
	}
}
class Main{
	public static void main(String[] args){
		final int MIN=-16777216;
		Scanner sc=new Scanner(System.in);
		int a=(255<<24)+(255<<16)+(255<<8)+255;
		//System.out.println("Please input n ( "+a+"<=a<="+(255<<24)+")");
		System.out.println("Please input red ,green and blue`s single color value");
		System.out.println("( 0<=value <=255 ) :");
		while(sc.hasNext()){
			Color c=new Color(sc.nextInt(),sc.nextInt(),sc.nextInt());
			System.out.println(c);
			System.out.println("RGB = 0x"+c.getRGB());
			System.out.println("Red = "+c.getRed());
			System.out.println("Green = "+c.getGreen());
			System.out.println("Blue = "+c.getBlue());
			System.out.println("-----------------");
			System.out.println("Please input n ( "+MIN+" <= n <= -1) : ");
			c=new Color(sc.nextInt());
			System.out.println(c);
			System.out.println("RGB = 0x"+c.getRGB());
			System.out.println("Red = "+c.getRed());
			System.out.println("Green "+c.getGreen());
			System.out.println("Blue = "+c.getBlue());
			System.out.println();
			System.out.println("Please input red ,green and blue`s single color value :");
		}

	}
}