Java 1020

package com.pm;/** * 游泳池费用计算，面向对象； * @author 周博 */import java.util.Scanner;public class Round {public static void main(String[] args) {Scanner sc = new Scanner(System.in);System.out.printf("请输入半径：");double a = sc.nextDouble();Roundnoe y = new Roundnoe(a);System.out.println("过道的费用：" + y.road());System.out.println("围墙的费用：" + y.wall());}}

package com.pm;public class Roundnoe{private double r;public Roundnoe(double r) {this.r = r;}/** * 路 */public double road(){double aprice = 10 * (Math.PI * (this.r + 3) * (this.r + 3) - Math.PI* this.r * this.r);return aprice;}/** * 围墙 */public double wall(){double bprice = (Math.PI * 2 * (this.r + 3)) * 8;return bprice;}}<pre name="code" class="java">package com.pm;/** * 钟 * @author 周博 */public class Test03 {public static void main(String[] args) throws Exception {Clock c = new Clock();while (true) {System.out.println(c.showTime());c.go();Thread.sleep(1000);}}}

package com.pm;import java.util.Calendar;public class Clock {private int hour;private int min;private int second;public Clock(){Calendar Cal = Calendar.getInstance();hour = Cal.get(11);min = Cal.get(12);second = Cal.get(13);}public void go() {second++;if (second == 60) {min++;if (min == 60) {hour++;if (hour == 24) {hour = 0;}}}}public String showTime() {String time = "";if (hour < 10) {time += "0";}time += hour + ":";if (min < 10) {time += "0";}time += min + ":";if (second < 10) {time += "0";}time += second;return time;}}

Java类的学习总结：（思维导图）