冒泡

今天的笔试题，小小的记录一下

 

package com.example.demo;

import org.springframework.boot.autoconfigure.SpringBootApplication;

import java.io.*;
import java.util.*;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) throws IOException {
        Map<Integer, String> read = readTxtFile("D:\\data\\list.txt");
        final StringBuffer stringBuffer = new StringBuffer();
        final Iterator<Integer> iterator = read.keySet().iterator();//keySet()返回值，所有key；iterator()遍历
        //当在缓冲区内扫描到字符时，会返回true， 否则会发生阻塞，等待数据输入。
        //hasNext("World")匹配到对应字符返回true，
        while (iterator.hasNext()){
             Integer key = iterator.next();
             String s = read.get(key);
            stringBuffer.append(s+" ");
        }
        String read1 = read(stringBuffer.toString());
        writeTxtFile("D:\\data\\outputtxt",read1);


    }
    //冒泡排序
    public static String read(String s){
        List<String> strings = new ArrayList<>(1000);
        String[] split1 = s.split(" ");
        for (int i=0;i<split1.length-1;i++){
            for (int j=0;j<split1.length-1;j++){
                String temp="";
                if (split1[j].length()>split1[j+1].length()){
                    temp=split1[j];
                    split1[j]=split1[j+1];
                    split1[j+1]=temp;
                }
            }

        }
        String split=Arrays.toString(split1);

        String substring = split.substring(1, split.length() - 1);
        return substring;

    }
    private static Map<Integer,String> readTxtFile(String filePath){
        Map<Integer, String> txtMap = new HashMap<Integer,String>(1000);//<key,value>
        try(FileInputStream fileInputStream = new FileInputStream(filePath);//从文件系统中的某个文件中获得输入字节
            InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);//创建一个使用默认字符集的 InputStreamReader。字节转换为字符
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);)//缓存区 BufferReader类用来包装所有其 read() 操作可能开销很高的 Reader（如 FileReader 和InputStreamReader）。
        {
            String line = null;
            Integer i = 0;
            while ((line =bufferedReader.readLine())!=null){//readline() 方法用于从文件读取整行,包括 “\n” 字符
                i=i+1;
                txtMap.put(i,line);
            }
        }
        catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }return txtMap;

    }
    private static void writeTxtFile(String filePath,String textList)throws IOException{
        final File file = new File(filePath);//通过给定的父抽象路径名和子路径名字符串创建一个新的File实例
        file.createNewFile();
        try(FileWriter fileWriter =new FileWriter(file);//字符向流中写入数据
            final BufferedWriter bufferedWriter = new BufferedWriter(fileWriter)){//BufferedWriter加入了缓冲技术,将字符读取对象作为参数
            for (String text:textList.split(", ")){//循环textList赋值给text
                bufferedWriter.write(text);//text写入
                bufferedWriter.newLine();//使用自己的行分隔符概念
            }
            bufferedWriter.flush();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

}