java语言程序设计(基础篇)第二章程序练习题答案

2.1（将摄氏温度转化为华氏温度）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter a degree in celsius: ");double Celsius = input.nextDouble();double Fahrenheit;Fahrenheit = (9.0/5) * Celsius + 32;System.out.println(Celsius+ " Celsius is"+ Fahrenheit + " Fahrenheit");}}2.2（计算圆柱体的体积）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the radius and length of a cylinder: ");double radius = input.nextDouble();double length =input.nextDouble();double area = radius * radius * Math.PI;double volume = area * length;System.out.println("The area is " + area);System.out.println("The volume is " + volume);}}2.3（将英尺转换为米）import java.util.Scanner;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter a value for feet: ");double feet = input.nextDouble();double meters = feet * 0.305;System.out.println(feet+ " feet is " + meters + " meters");}}2.4（将磅转换为千克）import java.util.Scanner;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter a number in pounds: ");double pounds = input.nextDouble();double kilograms = pounds * 0.454;System.out.println(pounds + " pounds is " + kilograms+ " kilograms");}}2.5（财务应用程序：计算消费）import java.util.Scanner;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the subtotal and gratuity rate: ");double subtotal = input.nextDouble();double Gratuity = input.nextDouble();double gratuity = subtotal * Gratuity * 0.01;double total = gratuity + subtotal;System.out.println("The gratuity is $" + gratuity + " and total is " + total);}}2.6（求一个整数个位数的和）import java.util.Scanner;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter a number between 0 and 1000: ");int number = input.nextInt();int sum = number % 10 + (number / 10) % 10 + (number / 100) % 10;System.out.println("The sum of the digits is " + sum);}}2.7（求出年数）import java.util.Scanner;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the number of minutes: ");double minutes = input.nextDouble();int years = (int)minutes / (60*24*365);int days = (int)minutes / (60*24) - ((int)minutes / (60*24*365)) * 365;System.out.println(minutes+ "minutes is approximately " + years + " years and " + days + " days");}}2.8（当前时间）import java.util.*;public class ShowXureentTime {public static void main(String[] args) {// TODO Auto-generated method stublong totalMilliseconds= System.currentTimeMillis();//得到1970年1月1日到现在的毫秒数long totalSeconds = totalMilliseconds / 1000;//将总毫秒转化为总秒long currentSecond = totalSeconds % 60;//当前的秒数long totalMinutes = totalSeconds / 60;//得到总的分钟long currentMinute = totalMinutes % 60;//当前的分钟数long totalHours = totalMinutes / 60;//得到总小时Scanner input = new Scanner(System.in);System.out.print("Enter the time zone offset to GMT: ");long zone = input.nextInt();long currentHour = totalHours % 24 + zone;//当前的小时数if(currentHour <0) {currentHour = currentHour + 24;}System.out.println("Current time is " + currentHour + ":" + currentMinute + ":" + currentSecond + " GMT");}//GMT世界时}2.9（物理：加速度）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter v0, v1 and t: ");double v0 = input.nextDouble();double v1 = input.nextDouble();double t = input.nextDouble();double acceleration = (v1 - v0) / t;System.out.println("The average acceleration is " + String.format("%.4f", acceleration));}}2.10（科学：计算能量）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the amount of water in kilograms: ");double M = input.nextDouble();System.out.print("Enter the initial temperature: ");double temperature1 = input.nextDouble();System.out.print("Enter the final temperature: ");double temperature2 = input.nextDouble();double energy= M* (temperature2- temperature1) * 4184;System.out.println("The energy needed is " + energy);}}2.1（人口统计）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the number of years: ");int year = input.nextInt();int population = 312032486;int temp =(365*12*60*60/7)-(365*12*60*60/13)+(365*12*60*60/45);//j = 诞生-死亡+移民迁入;for(int i = 1 ;i <= year ;i ++ ) {population = temp + population ;}System.out.println("The population in "+ year+ " years is " + population);}}2.12（物理：求出跑道的长度）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter speed and acceleration: ");double speed = input.nextDouble();double acceleration = input.nextDouble();double length = speed * speed / (2 * acceleration);System.out.println("The minimum runway length for this airplane is " + String.format("%.3f", length));}}2.13（财务应用程序：复利值）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the monthly saving aomunt: ");double monthly = input.nextDouble();double money = 0;for(int i = 1; i <= 6; i++) {money = (monthly + money) * (1 + 0.00417);}System.out.println("After the sixth month, the account value is " + String.format("%.2f", money));}}2.14（医疗应用程序：计算BMI）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter weight in pounds: ");double pounds = input.nextDouble();double kilogram = pounds * 0.45359237;System.out.print("Enter height in inches: ");double inches = input.nextDouble();double meter = inches * 0.0254;double BMI = (kilogram / (meter * meter)) ;System.out.println("BMI is " + String.format("%.4f", BMI));}}2.15（几何：两点间距离）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter x1 and y1: ");double x1 = input.nextDouble();double y1 = input.nextDouble();System.out.print("Enter x2 and y2: ");double x2 = input.nextDouble();double y2 = input.nextDouble();double distance = (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1);System.out.println("The distance between the two points is " + Math.pow(distance, 0.5));}}2.16（几何：六边形面积）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the side: ");double side = input.nextDouble();double area = 3 * Math.sqrt(3) / 2 * side * side;System.out.println("The area of the hexagon is " + area);}}2.17（科学：风寒温度）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the temperature in Fahrenheit between -58°F and 41°F: ");double Fahrenheit = input.nextDouble();System.out.print("Enter the wind speed (>=2) in miles per hour: ");double speed = input.nextDouble();double t = 35.74 + 0.6215 * Fahrenheit - 35.75 * Math.pow(speed, 0.16) + 0.4275 * Fahrenheit* Math.pow(speed, 0.16);System.out.println("The win chill index is " + String.format("%.5f", t));}}2.18（打印表格）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubSystem.out.println("a\t" + "b\t" + "pow(a, b)");System.out.println("1\t" + "2\t" + (int)Math.pow(1, 2));System.out.println("2\t" + "3\t" + (int)Math.pow(2, 3));System.out.println("3\t" + "4\t" + (int)Math.pow(3, 4));System.out.println("4\t" + "5\t" + (int)Math.pow(4,5));System.out.println("5\t" + "6\t" + (int)Math.pow(5, 6));}}2.19（几何：三角形的面积）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter three points fir a trinangle: ");double x1 = input.nextDouble();double y1 = input.nextDouble();double x2 = input.nextDouble();double y2 = input.nextDouble();double x3 = input.nextDouble();double y3 = input.nextDouble();double edge1= Math.pow((x2- x1) * (x2- x1) + (y2- y1) * (y2 - y1), 0.5);double edge2= Math.pow((x3- x2) * (x3- x2) + (y3- y2) * (y3 - y2), 0.5);double edge3= Math.pow((x3- x1) * (x3- x1) + (y3- y1) * (y3 - y1), 0.5);double s =(edge1 + edge2 + edge3) / 2;double area = Math.pow(s * (s - edge1) * (s - edge2) * (s - edge3), 0.5);System.out.println("The area of the tringle is " + String.format("%.1f", area));}}2.20（财务应用程序：计算利息）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter balance and interst rate (e.g, 3 for 3%): ");double balance = input.nextDouble();double annual = input.nextDouble();double interst = balance * ( annual / 1200);System.out.println("The interst is " +String.format("%.5f", interst));}}2.21（财务应用：计算未来投资值）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter investment amount: ");double investment = input.nextDouble();System.out.print("Enter annual interest rate in percentage: ");double interest = input.nextDouble();interest = interest / 100 / 12;System.out.print("Enternumber of yuears: ");double years = input.nextDouble();double value = investment * Math.pow((1 + interest), (years * 12));System.out.println("Accumulated value is $" + String.format("%.2f", value));}}2.22（财务应用：货币单位）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter an amount in int, for example 1156: ");int amount = input.nextInt();int remainingAmount = amount;int numberOfOneDollars = remainingAmount / 100;remainingAmount = remainingAmount % 100;int numbersOfQuarters = remainingAmount / 25;remainingAmount = remainingAmount % 25;int numberOfDimes = remainingAmount / 10;remainingAmount = remainingAmount % 10;int numberOfNickels = remainingAmount / 5;remainingAmount = remainingAmount % 5;int numberOfPennies = remainingAmount;System.out.println("Your amount "+ amount+ " consosts of");System.out.println(" " + numberOfOneDollars + " dollars");System.out.println(" " + numbersOfQuarters + "quarters");System.out.println(" " + numberOfDimes + " dimes");System.out.println(" " + numberOfNickels + " nickels");System.out.println(" " + numberOfPennies + " pennies");}}2.23（驾驶费用）import java.util.*;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print("Enter the driving distance: ");double drivingDistance = input.nextDouble();System.out.print("Enter miles per gallon: ");double milesPerGallon = input.nextDouble();System.out.print("Enter price per gallon: ");double pricePerGallon = input.nextDouble();double costOfDriving= drivingDistance/ milesPerGallon * pricePerGallon;System.out.print("The cost of driving is $" + String.format("%.2f", costOfDriving));}}。