JAVA学习笔记——JAVA语言程序设计第十版第二章习题

2019-11-08 02:04:54

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import java.math.BigDecimal;import java.math.RoundingMode;import java.text.DecimalFormat;import java.text.NumberFormat;import java.util.Formatter;import java.util.Scanner;public class ExerciseTwo { public static void main(String[] args) { // TODO Auto-generated method stub //创建并初始化Scanner实例 Scanner input = new Scanner(System.in); System.out.PRintln("2.1题目"); //提示用户输入摄氏温度 System.out.println("请输入温度："); int centigrade1 = input.nextInt(); //代入公式转化为华氏温度 double fahrenheit1 = (9 / 5.0) * centigrade1 + 32; System.out.println("Enter a degree in Centigrade : " + centigrade1); System.out.println(centigrade1 + " centigrade is " + fahrenheit1 + " Fahrenheit"); System.out.println("========================================================="); System.out.println("2.2题目"); //提示用户输入半径 System.out.println("请输入半径："); double radius2 = input.nextDouble();// //提示用户输入高 System.out.println("请输入高："); double length2 = input.nextDouble(); //代入公式计算面积 double area2 = radius2 * radius2 * Math.PI; //代入公式计算体积 double volume2 = area2 * length2; System.out.println("Enter th radius and length of a cylinder : " + radius2 + " " + length2 + "/n" + "The area is " + (float) area2 + "The volume is " + (float) volume2); System.out.println("========================================================="); System.out.println("2.3题目"); //提示用户输入英尺 System.out.println("请输入英尺数："); double feet3 = input.nextDouble(); //转换米 double meter3 = feet3 * 0.305; System.out.println("Enter a value for feet : " + feet3 + "/n" + feet3 + " feet is " + meter3 + " meters"); System.out.println("========================================================="); System.out.println("2.4题目"); //提示用户输入磅数 System.out.println("请输入重量：（磅）"); double pounds4 = input.nextDouble(); //转换千克 double kilogram4 = pounds4 * 0.454; System.out.println("Enter a number in pounds : " + pounds4 + "/n" + pounds4 + " pounds is " + kilogram4 + " kilograms"); System.out.println("========================================================="); System.out.println("2.5题目"); System.out.println("请输入一笔费用："); int subtotal5 = input.nextInt(); System.out.println("请输入酬金率："); int gratuityRate5 = input.nextInt(); float gratuity5 = subtotal5 * (float)gratuityRate5 / 100; float total5 = subtotal5 + gratuity5; System.out.println("Enter the subtotal and a gratuity rate : " + subtotal5 + " " + gratuityRate5 + "/n" + "The gratuity is $" + gratuity5 + " and total is $" + total5); System.out.println("========================================================="); System.out.println("2.6题目"); //死板式衔套if式 System.out.println("请输入0-1000的任意整数："); System.out.println("2.6使用死板方法"); int number6 = input.nextInt(); int sum6 = 0; int bit6; int ten6; int hundred6; System.out.println("Enter a number between 0 and 1000: " + number6); if (number6 == 1000) { sum6 = 1; } else { if (number6 >= 100 && number6 <= 999) { //如果输入的数是百位数 //对十求余取得个位 bit6 = number6 % 10; //利用int类型会截断小数点的特性 //把输入的数变为十位数 number6 = number6 / 10; ten6 = number6 % 10; //同理取得百位数 number6 = number6 / 10; hundred6 = number6 % 10; sum6 = bit6 + ten6 + hundred6; System.out.println("The sum of the digits is " + sum6); } else { //当输入的数是十位数时的情况 if (number6 >= 10 && number6 <= 99) { bit6 = number6 % 10; number6 = number6 / 10; ten6 = number6 % 10; sum6 = bit6 + ten6; System.out.println("The sum of the digits is " + sum6); } else { //当输入的数是个位数的情况 if(number6 >= 1 && number6 <= 9) { System.out.println("Enter a number between 0 and 1000: " + number6); } else { sum6 = 0; System.out.println("The sum of the digits is " + sum6); } } } } System.out.println("========================================================="); System.out.println("2.6应用while循环方法"); System.out.println("Enter a number between 0 and 1000: " + number6); /*利用int类型不存储小数点的特性获得非十位以上的数 * 再将输入的数除以10 * 缩减末尾数 * 再相加 * */ while(number6 / 10 != 0) { sum6 = sum6 + number6 % 10; number6 = number6 / 10; } //输入的数为个位数 sum6 = sum6 + number6 % 10; System.out.println("The sum of the digits is " + sum6); System.out.println("========================================================="); System.out.println("2.7题目"); System.out.println("输入分钟数："); long minutes7 = input.nextLong(); //输入的小时数 long hours7 = minutes7 / 60; //输入的天数 long day7 = hours7 / 24; //输入的年数 long years7 = day7 / 365; //多出多少天 long days7 = day7 - years7 * 365; System.out.println("Enter the number of minutes: " + minutes7 + "/n" + minutes7 + " minutes is approximately " + years7 + " years and " + days7 + " days"); System.out.println("========================================================="); System.out.println("2.9题目"); System.out.println("请输入初始速度：(米/秒)"); float v0 = input.nextFloat(); System.out.println("请输入终止速度：(米/秒)"); float v = input.nextFloat(); System.out.println("请输入时间段：(秒)"); float t = input.nextFloat(); System.out.println("Enter v0, v1, and t: " + v0 + " " + v + " " + t); float a9 = (v - v0) / t; //创建BigDecimal实例，并传入加速度的值 BigDecimal bd = new BigDecimal(a9); //设置BigDecimal的取舍模式 bd = bd.setScale(4, RoundingMode.HALF_DOWN); //创建新的变量存储BigDecimal取舍后加速度的值 String lastA = bd.toString(); System.out.println("The average acceleration is " + lastA); System.out.println("========================================================="); System.out.println("2.10题目"); System.out.println("请输入重量：(千克，kg)"); double waterKilograms = input.nextDouble(); System.out.println("请输入初温：(摄氏度，°C)"); double temperature = input.nextDouble(); System.out.println("请输入最终温度：(摄氏度，°C)"); double finalTemperature = input.nextDouble(); System.out.println("Enter the amount of water in kilograms: " + waterKilograms + "Enter the initial temperature: " + temperature + "Enter the final temperature: " + finalTemperature); double energy = waterKilograms * (finalTemperature - temperature) * 4184; System.out.println("The energy needed is " + energy); System.out.println("========================================================="); System.out.println("2.11题目"); System.out.println("输入年数："); int numberOfYears = input.nextInt(); //计算输入的年数等于多少秒 long secondsOfYear = numberOfYears * 365 * 24 * 60 * 60; /*算法公式 * 人口变化数 = 时间 / 诞生时间 - 时间 / 死亡时间 + 时间 / 迁入时间 */ long population = 312032486 + secondsOfYear / 7 - secondsOfYear / 13 + secondsOfYear / 45; System.out.println("Enter the number of years：" + numberOfYears + "/n" + "The population in " + numberOfYears + " years is " + population); System.out.println("========================================================="); System.out.println("2.12题目"); System.out.println("请输入速度：（米/秒）"); float v12 = input.nextFloat(); System.out.println("请输入加速度：（米/平方秒）"); float a12 = input.nextFloat(); double runwayLength = Math.pow(v12, 2) / 2* a9; DecimalFormat df9 = new DecimalFormat("0.000"); df9.setRoundingMode(RoundingMode.HALF_UP); System.out.println("Enter speed and acceleration：" + v12 + " " + a12 +"/n" + "The minimum runway length for this airplane is " + df9.format(runwayLength)); System.out.println("========================================================="); System.out.println("2.13题目"); System.out.println("请输入存入金额："); int monthlySave = input.nextInt(); double monthlyRate = 0.05 / 12; System.out.println("请输入定期时间：（月）"); int monthly = input.nextInt(); double accountValue = 0; for(int i = 1; i <= monthly; i++) { accountValue = (monthlySave + accountValue) * (1 + monthlyRate); } NumberFormat nFormat = NumberFormat.getNumberInstance(); nFormat.setMaximumFractionDigits(2); nFormat.setMinimumFractionDigits(2); nFormat.setRoundingMode(RoundingMode.HALF_UP); System.out.println("Enter the monthly saving amount: " + monthlySave + "/n" + "After the " + monthlySave + " months, the account value is $" + nFormat.format(accountValue)); System.out.println("========================================================="); System.out.println("2.14题目"); System.out.println("请输入体重：（磅）"); double pounds14 = input.nextDouble(); double kilogram14 = pounds14 * 0.45359237; System.out.println("请输入身高：（英寸）"); double inches = input.nextDouble(); double meters = inches * 0.0254; double bmi = kilogram14 / Math.pow(meters, 2); DecimalFormat dFormat = new DecimalFormat("0.0000"); dFormat.setRoundingMode(RoundingMode.HALF_UP); System.out.println("Enter weight in piunds: " + pounds14 + "/n" + "Enter height in inches: " + inches + "/n" +"BMI is " + dFormat.format(bmi)); System.out.println("========================================================="); System.out.println("2.15题目"); System.out.println("请输入x1："); double xOne = input.nextDouble(); System.out.println("请输入y1："); double yOne = input.nextDouble(); System.out.println("请输入x2："); double xTwo = input.nextDouble(); System.out.println("请输入y2："); double yTwo = input.nextDouble(); double firstDistance = Math.pow((xTwo - xOne), 2); double secondDistance = Math.pow((yTwo - yOne), 2); double distance = Math.sqrt(firstDistance + secondDistance); System.out.println("Enter x1 and y1: " + xOne + " " + yOne + "/n" + "Enter x2 and y2: " + xTwo + " " + yTwo + "/n" + "The distance between the two points is " + distance); System.out.println("========================================================="); System.out.println("2.16题目"); System.out.println("请输入六边形的边长："); double side1 = input.nextDouble(); double s1 = Math.pow(side1, 2) * Math.sqrt(3) * 3 / 2; DecimalFormat df1 = new DecimalFormat("0.0000"); df1.setRoundingMode(RoundingMode.HALF_UP); System.out.println("Enter the side: " + side1 +"/n" + "The area of hexagon is " + df1.format(s1)); System.out.println("========================================================="); System.out.println("2.17题目"); System.out.println("Please enter the temperature in Fahrenheit between 58°F and 41°F: "); double temperature1 = input.nextDouble(); System.out.println("Please enter the speed(>=)2 in miles per hour: "); double speed1 = input.nextDouble(); //代入公式 double temperatureWindChill = 35.74 + 0.6215 * temperature1 - 35.75 * Math.pow(speed1, 0.16) + 0.4275 * temperature1 * Math.pow(speed1, 0.16); DecimalFormat dFormat2 = new DecimalFormat("0.00000"); dFormat2.setRoundingMode(RoundingMode.HALF_UP); System.out.println("The wind chill index is " + dFormat2.format(temperatureWindChill)); System.out.println("========================================================="); System.out.println("2.18题目"); System.out.printf("%-5s%-5s%-5s%n", "a", "b", "pow(a, b)"); for(int i = 1; i < 6; i++) { int s = (int)Math.pow(i, i + 1); System.out.printf("%-5s%-5s%-5s%n", i, i + 1, s); } System.out.println("========================================================="); System.out.println("2.19题目"); System.out.println("Enter three point for a triangle: "); 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 sideTri1 = Math.sqrt( Math.pow((x2 - x1), 2) + Math.pow((y2 - y1), 2)); double sideTri2 = Math.sqrt( Math.pow((x3 - x2), 2) + Math.pow((y3 - y2), 2)); double sideTri3 = Math.sqrt( Math.pow((x3 - x1), 2) + Math.pow((y3 - y1), 2)); double s = (sideTri1 + sideTri2 + sideTri3) / 2; double area21 = Math.sqrt(s * (s - sideTri1) * (s - sideTri2) * (s - sideTri3)); DecimalFormat df19 = new DecimalFormat("0.0"); df19.setRoundingMode(RoundingMode.HALF_UP); System.out.println("The area of the triangle is " + df19.format(area21)); System.out.println("============================================================"); System.out.println("2.20题目"); System.out.println("Enter balance and interest rate (e.g., 3 for 3%): "); double balance = input.nextDouble(); double rateOfYear = input.nextDouble(); double interestRate = balance * (rateOfYear / 1200); DecimalFormat dFormat3 = new DecimalFormat("0.00000"); dFormat3.setRoundingMode(RoundingMode.HALF_UP); System.out.println("The interest is " + dFormat3.format(interestRate)); System.out.println("============================================================"); System.out.println("2.21题目"); System.out.println("Enter investment amount: "); double investment = input.nextDouble(); System.out.println("Enter annual interest rate in percentage: "); double annualRate = input.nextDouble(); System.out.println("Enter number of years: "); double numberOfYear2 = input.nextDouble(); double accumulatedValue = investment * Math.pow((1 + annualRate / 12), (numberOfYear2 * 12)); DecimalFormat df21 = new DecimalFormat("0.00"); df21.setRoundingMode(RoundingMode.HALF_UP); System.out.println("Accumulation value is $" + df21.format(accumulatedValue)); System.out.println("============================================================"); System.out.println("2.22题目"); System.out.println("Enter an amount:"); int amount = input.nextInt(); int dolar = amount / 100; int cent = amount % 100; System.out.println("The amount is " + dolar + "美元" + cent + "美分"); System.out.println("============================================================"); System.out.println("2.23题目"); System.out.println("Enter the driving distance: "); double distance23 = input.nextDouble(); System.out.println("Enter miles per gallon: "); double milesPerGallon = input.nextDouble(); System.out.println("Enter price per gallon: "); double price = input.nextDouble(); double cost = distance23 / milesPerGallon * price; DecimalFormat df23 = new DecimalFormat("0.00"); df23.setRoundingMode(RoundingMode.HALF_UP); System.out.println("The cost of driving is $" + df23.format(cost)); }}

以上代码，有关DecimalFormate等数字格式化类的知识：http://blog.csdn.net/vinfai/article/details/55517660 以上，有关printf的知识：http://blog.csdn.net/vinfai/article/details/56009415

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