09上--FizzBuzz和基本IO语句.ppt

1、FizzBuzz和基本的IO语句,主讲：曲美霞,FizzBuzz 和基本的IO语句,FizzBuzz 基本的IO语句,FizzBuzz:,1 问题来源 2 问题描述 3 解决方案 4 新FizzBuzz,? FizzBuzz,Using FizzBuzz to Find Developers who GrokCoding The programmers Stairway to Heaven 用最简单的方法测试出来谁会编程 谁不会编程,1 问题来源:,Author: Imran Reasons: Imran discover that people who struggle to code do

2、nt just struggle on big problems,or even smallish problems ,they struggle with tiny problems. So I set out to develop questions that can identify this kind of developer and came up with a class of questions I call “FizzBuzz Questions” named after a game children often play (or are made to play) in s

3、chools in the UK. 来自:,2 问题描述:,English:,Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”.,FizzBuzz 问题(Imran)总结：,问题描述:

4、 1100的整数, 如果是3的倍数则用Fizz替换输出; 如果是5的倍数则用Buzz替换输出; 既是3又是5的倍数则用FizzBuzz替换输出. 其余正常输出,2 解决方案:,1100 整数,被3整除,被5整除,3和5整除,问题抽象：,解决方案1： -if嵌套,for(int i=1;i=100;i+) if(i%15=0) System.out.print (“FizzBuzz”); else if(i%3=0) System.out.print (“Fizz”); else if(i%5=0) System.out.print (“Buzz”); else System.out.print

5、 (i); ,解决方案2 if和continue,for(int i=1;i=100;i+) if(i%15=0) System.out.print (“FizzBuzz”); continue; if(i%3=0) System.out.print (“Fizz”); continue; if(i%5=0) System.out.print (“Buzz”);continue; System.out.print (i); ,解决方案3switch和break,for(int i=1;i=100;i+) int k=1; if(i%3= =0) k+; if(i%5= =0) k+=2; sw

6、itch(k) case 1: System.out.println(i); break; case 2: System.out.println(“Fizz”); break; case 3: System.out.println(“Buzz”); break; case 4: System.out.println(“FizzBuzz”); break; ,解决方案4使用递归,public class FizzBuzz public static String fizzbuzz(int i) if(i=0) return “”; if(i%15=0) return fizzbuzz(i-1)+

7、”FizzBuzzzn”; if(i%3=0) return fizzbuzz(i-1)+”Fizzn”; if(i%5=0) return fizzbuzz(i-1)+”Buzzn”; return fizzbuzz(i-1)+i+”n”; public static void main(String args) System.out.println(fizzbuzz(100); ,解决方案5 OO,public class FizzBuzz public void printfizzbuzz( ) for(int i=1;i=100;i+) if(i%15=0) System.out.pr

8、intln(FizzBuzz); else if(i%3=0) System.out.println(Fizz); else if(i%5=0) System.out.println(Buzz); else System.out.println(i); ,public class TestFizz public static void main(String args) FizzBuzz fizz=new FizzBuzz(); fizz.printfizzbuzz(); ,问题深入：,如果此应用中，要求提供人机交互，从用户的输入中直接判断输入数是否能被3，被5或者被3和5整除呢？该如何解决？

9、,4 新FizzBuzz问题,接受用户从键盘的输入, 如果是3的倍数则用Fizz替换输出; 如果是5的倍数则用Buzz替换输出; 既是3又是5的倍数则用FizzBuzz替换输出. 其余则输出”你输入的数是XXX,不能被3也不能被5整除”,补充：java基本的输入输出语句,控制台输出(Console)： (1) Java 风格 (2) C风格（JDK5）,控制台输出,Java风格 -直接输出字符串，非字符串类型会自动转化为字符串。 System.out.println(y); System.out.print(y);,控制台输出,C风格(JDK5以后) -使用指定格式字符串和参数将格式化的字符串

10、写入此输出流的便捷方法 System.out.printf(“%,d”,1200000); System.out.printf(“%x”,42);,控制台键盘输入：,使用BufferedReader类(java.io包) 使用main方法传参 使用Scanner文本扫描器(java.util包),BufferedReader类,-从键盘输入流读入字符串，再转化为相应的类型。 import java.io.*; public class BufferIn public static void main(String args) throws IOException InputStreamRead

11、er ins = new InputStreamReader(System.in); BufferedReader br = new BufferedReader(ins); String str = br.readLine(); ,(2) 使用args字符串数组参数传参输入,public class ArgsInput public static void main(String args) for(int i=0;iargs.length;i+) System.out.println(“您的输入是:”+argsi); ,import java.util.Scanner; public class ScannerInput public static