2014.10.20--Java基础课第五天学习总结

作业1：

package com.hechao;
/**
 * 输入游泳池半径，计算游泳池的周长
 * 绕游泳池修3米宽的路，在路边修围栏
 * 围栏8元每米，修路10元每平方米
 * 需要花费多少钱？
 */
import java.util.Scanner;

/**
 * 圆类
 * @author hechao
 *
 */
public class Circle {
	private double radius;
	/**
	 * 构造器
	 * @param radius
	 */
	public Circle(double radius) {
		this.radius = radius;
	}
	/**
	 * 求面积
	 * @param radius
	 * @return
	 */
	public double getArea(double radius){
		double area = 3.1416 * radius * radius;
		return(area);
	}
	/**
	 * 求周长
	 * @param radius
	 * @return
	 */
	public double getCircumference(double radius){
		double circ = 3.1416 * 2 * radius;
		return(circ);
	}
	/**
	 * 实例
	 * @param args
	 */
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double rad;
		do {
			System.out.print("请输入半径：");
			rad = sc.nextDouble();
		} while (rad < 0);
		Circle c = new Circle(rad);
		Circle s = new Circle(rad);
		double pay = 8 * c.getCircumference(rad+3) + 10 * (s.getArea(rad + 3) - s.getArea(rad));		
		System.out.printf("所需费用为%.2f元\n", pay);
		sc.close();
	}
}

作业2

package com.hechao;

import java.util.Calendar;

/**
 * 时钟
 * @author hechao
 *
 */
public class Clock {
	private int hour;
	private int minute;
	private int second;
	/**
	 * 构造器
	 * @param hour
	 * @param minute
	 * @param second
	 */
	public Clock() {
		Calendar cal = Calendar.getInstance();
		hour = cal.get(hour);
		minute = cal.get(minute);
		second = cal.get(second);
	}
	/**
	 * 走字
	 */
	public void go(){
		second++;
		if(second == 60){
			second = 0;
			minute++;
			if(minute == 60){
				hour++;
				if(hour == 24){
					hour = 0;
				}
			}
		}
	}
	/**
	 * 显示时间
	 */
	public String showTime(){
		String time = "";
		if(hour < 10){
			time += "0";
		}
		time += hour + ":";
		if(minute < 10) {
			time += "0";
		}
		time += minute + ":";
		if(second < 10) {
			time += "0";
		}
		time += second;
		return time;
	}
	public static void main(String[] args) throws Exception {
		Clock c = new Clock();
		while(true) {
			System.out.println(c.showTime());
			c.go();
			Thread.sleep(1000);	// 让当前程序休眠1秒钟
		}
	}
}

心得：类与对象的创建使用还不熟悉，需多花时间。周末玩得太累，上课没精神，累了， 还是早点休息。