Java-第六章程序清单.docx

习题6.2（求一个整数各位数之和）import java.util.Scanner;public class sumIf public static void main(String args) / TODO Auto-generated method stubSystem.out.print(请输入一个整数：);Scanner input = new Scanner(System.in);long n = input.nextInt();System.out.print(输入的整数i= + n + 的各个数字的和是 + sumDigits(n);public static long sumDigits(long k)long sum = 0;while( k != 0) sum += k % 10;k /= 10;return sum;习题6.4（反向显示一个整数）import java.util.Scanner;public class reverse public static void main(String args) / TODO Auto-generated method stubSystem.out.print(请输入一个整数);Scanner input = new Scanner(System.in);int number1 = input.nextInt();reverse(number1);public static int reverse(int number) int i;while(number != 0)System.out.print(number%10);number /= 10;return 0;习题6.6（显示图案，此方法只能在10以内对其）import java.util.*;public class displayPattern1 public static void main(String args) / TODO Auto-generated method stubSystem.out.print(请输入一个整数);Scanner input = new Scanner(System.in);int n = input.nextInt();displayPattern(n);public static void displayPattern(int i) for(int j = 1; j = i; j+) for(int k = 0; k = 10)System.out.print( );for(int k = j; k 0; k-) System.out.print(k + );System.out.println();程序清单6-1（调用max方法）public class TestMax public static void main(String args) / TODO Auto-generated method stubint i = 5;int j = 2;int k = max(i, j);System.out.println(the maxinum of + i + and + j + is + k);public static int max(int num1, int num2) int result;if (num1 num2)result = num1;elseresult = num2;return result;程序清单6-2（void方法示例，打印给定分数的等级）public class TestVoidMethod public static void main(String args) / TODO Auto-generated method stubSystem.out.print(The grade is );printGrade(78.5);System.out.print(The grade is );printGrade(59.5);public static void printGrade(double score) if(score =90.0) System.out.println(A);else if(score =80.0) System.out.println(B);else if(score =70.0) System.out.println(C);else if(score =60.0) System.out.println(D);else System.out.println(F);程序清单6-3（void方法的示例，与程序清单做对比，打印一个分数的等级）public class TestReturnVoidMethod public static void main(String args) System.out.print(The frade is + getGrade(78.5);System.out.print(nThe frade is + getGrade(59.5);public static char getGrade(double score) if (score = 90)return A;else if (score = 80)return B;else if (score = 70)return C;else if (score = 60)return D;elsereturn F;程序清单6-4（通过传值进行参数传递）public class Increment public static void main(String args) / TODO Auto-generated method stubint x = 1;System.out.println(Before the call, x is + x);increment(x);System.out.println(After the call, x is + x);public static void increment(int n) n+;System.out.println(n inside the method is + n);程序清单6-5（按值传递参数）public class TestPassByValue public static void main(String args) / TODO Auto-generated method stubint num1 = 1;int num2 = 2;System.out.println(Before invoking the swap method, num1 is + num1 + and num2 is + num2);swap(num1,num2);System.out.println(After invoking the swap method, num1 is + num1 + and num2 + num2);public static void swap(int n1, int n2) System.out.println(tIside the method);System.out.println(ttBefore swapping, n1 is + n1 + and n2 is + n2);int temp = n1;n1 = n2;n2 = temp;System.out.println(ttAfter swapping, n1 is + n1 + and n2 is + n2);程序清单6-6（程序模块化_求最大公约数）import java.util.Scanner;public class GreatestCommonDivisorMethod public static void main(String args) / TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print(Enter first integer: );int n1 = input.nextInt();System.out.print(Enter scond integer: );int n2 = input.nextInt();System.out.println(The greatest common divisor for + n1 + and + n2 + is + gcd(n1, n2);public static int gcd(int n1, int n2) int gcd = 1;int k = 2;while (k = n1 & k = n2) if (n1 % k =0 & n2 % k = 0)gcd = k;k+;return gcd;程序清单6-7（程序模块化，打印50以内的素数，输出结果与书上不一致）public class PrimeNumberMethod public static void main(String args) / TODO Auto-generated method stubSystem.out.println(The first 50 prime numbers are n);printprimeNumbers(50);public static void printprimeNumbers(int numberOfPrimes) final int NUMBER_OF_PRIMES_PER_LINE = 10;int count = 0;int number = 2;while(count numberOfPrimes) if(isPrime(number) count+;if(count % NUMBER_OF_PRIMES_PER_LINE = 0) System.out.printf(%-5sn, number);elseSystem.out.printf(%-5s, number);number+;public static boolean isPrime (int number)for(int divisor = 2; divisor = number / 2 ; divisor+) if(number % divisor = 0) return false;return true;程序清单6-8（将16进制转换为十进制）import java.util.Scanner;public class Hex2Dec public static void main(String args) / TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print(Enter a hex number: );String hex = input.nextLine();/Sting是什么， input.nextLine又是什么System.out.println(The decimal value for hex number + hex + is + hexToDecimal(hex.toUpperCase();public static int hexToDecimal(String hex) int decimalValue = 0;for (int i = 0; i = A & ch num2)return num1;elsereturn num2;public static double max(double num1, double num2) if(num1 num2) return num1;elsereturn num2;public static double max(double num1, double num2, double num3) return max(max(num1, num2), num3);程序清单6-10（生成随机字符）public class RandomCharacter public static char getRandomCharacter(char ch1, char ch2) return (char)(ch1 + Math.random() * (ch2 - ch1 + 1);public static char getRandomLowerCaseLetter() return getRandomCharacter(a, z);public static char getRandomUpperCaseLetter() return getRandomCharacter(A, Z);public static char getRandomDigtCharacter() return getRandomCharacter(0, 9);public static char getRandimCharacter() return getRandomCharacter(u0000, uFFFF);程序清单6-11（生成随机数，调用了6-10的方法）public class TestRandomCharacter public static void main(String args) / TODO Auto-generated method stubfinal int NUMBER_OF_CHARS = 175;final int CHARS_PER_LINE = 25;for(int i = 0; i NUMBER_OF_CHARS; i+) char ch = RandomCharacter.getRandomLowerCaseLetter();if(i + 1) % CHARS_PER_LINE = 0)System.out.println(ch);elseSystem.out.print(ch);程序清单6-12（方法抽象，逐步求精）import java.util.Scanner;public class PrintCalendar public static void main(String args) / TODO Auto-generated method stubScanner input = new Scanner(System.in);System.out.print(Enter full yuer (e.g., 2012): );int year = input.nextInt();System.out.print(Enter month as a number between 1 and 12: );int month = input.nextInt();printMonth(year, month);public static void printMonth(int year, int month) printMonthTitle(year, month);printMonthBody(year, month);public static void printMonthTitle(int year, int month) System.out.println( + getMonthName(month) + + year);System.out.println(-);System.out.println( Sun Mon Tue Wed Tue Fri Sat);public static String getMonthName(int month) String monthName = ;switch (month) case 1: monthName = January; break;case 2: monthName = Fanuary; break;case 3: monthName = March; break;case 4: monthName = April; break;case 5: monthName = May; break;case 6: monthName = June; break;case 7: monthName = July; break;case 8: monthName = August; break;case 9: monthName = September; break;case 10: monthName = October; break;case 11: monthName = November; break;case 12: monthName = December; break;return monthName;public static void printMonthBody(int year, int month) int startDay = getStartDay(year, month);int numberOfDaysInMonth = getNumberOfDaysInMonth(year, month);int i = 0;for(i = 0; i startDay; i+) System.out.print( );for(i = 0; i = numberOfDaysInMonth; i+) System.out.printf(%4d, i);if(i + startDay) % 7 = 0)System.out.println();System.out.println();public s