黑马程序员——IO流中的练习

来源：互联网发布：文华财经看盘软件编辑：程序博客网时间：2024/05/16 17:13

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需求：从键盘输入学生成绩信息，并将信息按照总分高低存入文件中

1、首先建立一个描述学生对象的类 Student，这个学生信息存储方式，按照需要覆写toString()、comperTo()、hashCode()、equals()等基本方法，另外一个学生类一般具备set()、get()方法，用来设置和获取学生信息，这个主要是集合章节的使用

2、键盘录入信息，键盘读取流；将信息先存到一个集合中以实现排序

3、录入完毕后，遍历集合并将集合中的数据使用输出流存入文件中

4、关闭资源，完成整个需求

代码实现如下：
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class Studentimplements Comparable<Student>{
     
    private String name;
    private float chinese;
    private float math;
    private float english;
    public Student(String name,float chinese,float math,float english){
        this.name = name;
        this.chinese = chinese;
        this.math = math;
        this.english = english;
    }
    public int compareTo(Student s){
        float t = s.getTotal();
        int num = new Float(this.getTotal()).compareTo(new Float(t));          //this.name.compareTo(s.name);
        return num;   //比较器的反转？
    }
    public String toString(){
        return "name:"+name+" chinese:"+chinese+" math:"+math+" english:"+english+" -->Total"+this.getTotal();
    }
    public void setName(String name){
        this.name = name ;
    }
    public void setChinese(float chinese){
        this.chinese = chinese;
    }
    public void setMath(float math){
        this.math = math;
    }
    public void setEnglish(float english){
        this.english = english;
    }
    public float getTotal(){
        return chinese + math + english;
    }
    public int hashCode(){
        return name.hashCode() + (int)getTotal()*39;
    }
    public boolean equals(Object obj){
        if(objinstanceof Student)
            throw new ClassCastException("类型不匹配！");
        Student s = (Student)obj;
        return this.name.equals(s.name) &&
            this.getTotal() == s.getTotal(); 
    }
}

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import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Iterator;
import java.util.TreeSet;
 
public class Storage {
 
    public static void main(String args[]){
     
        stor();
         
         
    }
    public static void stor(){ 
        TreeSet<Student> ts = new TreeSet<Student>();
        BufferedReader bufr= new BufferedReader(new InputStreamReader(System.in));
        try {
            String line = null;
            while((line = bufr.readLine()) != null){
                String[] ss = line.split(" ");
                 
                if(judge(line))//判断合法
                {
                    ts.add(new Student(ss[0], Float.parseFloat(ss[1]), Float.parseFloat(ss[2]),new Float(ss[3])));
                     
                }
                else
                {
                    if("over".equals(line))
                        break;
                    else
                        sop("输入数据非法，请重新输入");
                }
                 
            }
        }catch (IOException e) {
            sop("读取信息失败");
            e.printStackTrace();
        }finally{
            try {
                bufr.close();
            }catch (IOException e) {
                new  RuntimeException("读取信息关闭失败!");
                e.printStackTrace();
            }
             
        }
        //将信息存入文件中
        printts(ts);
    }
    public static void printts(TreeSet<Student> ts){
        BufferedWriter bufw = null;
        try {
            bufw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("stud.txt")));
            Iterator<Student> it = ts.iterator();
            while(it.hasNext()){
                Student s = it.next();
                String s0 = s.toString();
                try {
                    bufw.write(s0);
                    bufw.newLine();
                    bufw.flush();
                }catch (IOException e) {
                    sop("信息写入失败！！");
                    e.printStackTrace();
                }
            }
            try {
                bufw.close();
            }catch (IOException e) {
                sop("关闭写入流失败！");
                e.printStackTrace();
            }
             
        }catch (FileNotFoundException e1) {
            sop("信息写入失败！");
            e1.printStackTrace();
        }
    }
    public static boolean judge(String s){
        String[] ss = s.split(" ");
        if(ss.length == 4)
            return true;
        else
            return false;
    }
    public static void sop(Object obj){
        System.out.println(obj);
    }
}

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