【Java】实验七

1. 编写程序，在控制台窗口提示输入两个整数，然后接收这两个整数，并输出它们的和。（要求：键盘输入通过流封装System.in获取，不要使用Scanner类）

 

package com.ly.stream;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class InputStreamTest {
    public static void main(String[] args) {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String line=null;
        try{
            System.out.print("请输入第一个正整数a：");
            line = in.readLine();
            int a = Integer.parseInt(line);
            System.out.print("请输入第二个正整数b：");
            line = in.readLine();
            int b = Integer.parseInt(line);
            System.out.println("a+b=" + String.valueOf(a+b));
        }catch(Exception e){
            System.out.println("输入错误！");
            System.exit(0);
        }
    }
}

 

2. 设计学生类Student，属性：编号（整型）；姓名（字符串），成绩（整型）。编写一个程序：要求：（1）输入3个学生的姓名和成绩，将其姓名和成绩保存到data.txt中；（2）然后从该文件中读取数据，求得这五个学生的平均成绩。

package com.ly.file;

public class Student {
    int id;
    String name;
    int score;
    
    Student(){}
    public void setId(int id){
        this.id = id;
    }
    
    public void setName(String name){
        this.name = name;
    }
    
    public void setScore(int score){
        this.score = score;
    }
    
    public String toString(){
        return this.id + "\t" + this.name + "\t" + this.score + "\n";
    }
}

package com.ly.file;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        try{
            DataOutputStream out = new DataOutputStream(new FileOutputStream("D:\\student.txt"));
            String line;
            for(int i=0;i<3;i++){
                Student stu = new Student();
                
                System.out.print("学号：");
                line = in.readLine();
                int id = Integer.parseInt(line);
                stu.setId(id);
                
                System.out.print("姓名：");
                String name = in.readLine();
                stu.setName(name);
                
                System.out.print("成绩：");
                line = in.readLine();
                int score = Integer.parseInt(line);
                stu.setScore(score);
                
                out.writeBytes(stu.toString());
            }
            out.close();
        }catch(IOException e){
            System.out.println("文件写入失败！");
            System.exit(0);
        }
        
        try{
            DataInputStream din = new DataInputStream(new FileInputStream("D:\\student.txt"));
            int ScoreSum = 0;
            String line;
            for(int i=0;i<3;i++){
                line = din.readLine();
                int score = Integer.parseInt(line.trim().split("\t")[2]);
                ScoreSum += score;
            }
            System.out.println("平均成绩：" + ScoreSum/3);
        }catch(FileNotFoundException e){
            System.out.println("文件不存在！");
            System.exit(0);
        }catch(IOException e){
            System.out.println("文件读取失败！");
            System.exit(0);
        }
    }
}