Java——流、文件与正则表达式

0. 字节流与二进制文件

我的代码

我的总结

1. 字符流与文本文件

我的代码

我的总结

2. 缓冲流(结合使用JUint进行测试)

我的代码

main函数：
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;

import javax.swing.text.AbstractDocument.BranchElement;

public class WriteFile {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String fileName = "e:/bigdata.txt";
        int n = 1000_0000;
        Random r = new Random(100);
        try (PrintWriter pWriter = new PrintWriter(fileName)){
            for (int i = 0; i < n; i++) {
                pWriter.println(r.nextInt(11));
            }
        } catch (FileNotFoundException e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        
        /*try (BufferedReader br = new BufferedReader(new FileReader(new File(fileName)))){
            String string = null;
            int count=0;
            long sum=0;
            double average = 0.0;
            while ((string=br.readLine())!=null) {
                int num = Integer.parseInt(string);
                sum+=num;
                count++;
            }
            average=1.0*sum/count;
            System.out.format("count = %d,sum = %d,averge = %.5f",count,sum,average);
        } catch (FileNotFoundException e) {
            // TODO: handle exception
            e.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }*/
    }

}

Junit：
package test;

import static org.junit.jupiter.api.Assertions.*;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;

import org.junit.jupiter.api.Test;

class testRead {
    String fileName = "e:/bigdata.txt";
    @Test
    void testB() {
        try (BufferedReader br = new BufferedReader(new FileReader(new File(fileName)))){
            String string = null;
            int count=0;
            long sum=0;
            double average = 0.0;
            while ((string=br.readLine())!=null) {
                int num = Integer.parseInt(string);
                sum+=num;
                count++;
            }
            average=1.0*sum/count;
            System.out.format("count = %d,sum = %d,averge = %.5f",count,sum,average);
        } catch (FileNotFoundException e) {
            // TODO: handle exception
            e.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
    }
    @Test
    void testS() {
        try (Scanner sc = new Scanner(new File(fileName))){
            String string = null;
            int count=0;
            long sum=0;
            double average = 0.0;
            while (sc.hasNextLine()) {
                string = sc.nextLine();
                int num = Integer.parseInt(string);
                sum+=num;
                count++;
            }
            average=1.0*sum/count;
            System.out.format("count = %d,sum = %d,averge = %.5f",count,sum,average);
        } catch (FileNotFoundException e) {
            // TODO: handle exception
            e.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
    }

}

我的总结

我的代码

我的总结

我的代码

我的总结

我的代码

我的总结