IO流：将键盘录入的学生成绩进行排序写入文件中

小灰灰 2021-09-20 12:26 333阅读 0赞

【需求】：

有五个学生，每个学生有三门课的成绩  
从键盘输入以上数据（包括姓名，三门课的成绩）  
输入的格式如：zhangsan,30,40,50    计算出总成绩  
并把学会的信息和计算出的总分数高低顺序存放在磁盘文件"student.txt"

【代码】：

import java.io.*;
    import java.util.*;
    class Student implements Comparable<Student>
    {
    	private String name;
    	private double chinese;
    	private double math;
    	private double english;
    	private double sum;
    
    	public double getSum(){
    		return this.sum;
    	}
    	Student(String name,double chinese,double math,double english){
    		this.name=name;
    		this.chinese=chinese;
    		this.math=math;
    		this.english=english;
    		sum=chinese+math+english;
    	}
    
    	//重写hashCode()方法
    	public int hashCode(){
    		return name.hashCode();
    	}
    
    	//重写equals()方法
    	public boolean equals(Object o){
    		if(!(o instanceof Student)){
    			throw new RuntimeException("不是学生类对象");
    		}
    		Student s=(Student)o;
    		return this.name.equals(s.name)&&this.sum==s.sum;
    	}
    	public int compareTo(Student s){
    		int num=new Double(this.sum).compareTo(new Double(s.sum));
    		if(num==0){
    			return this.name.compareTo(s.name);
    		}
    		return num;
    	}
    	public String toString(){
    		return name+","+chinese+","+math+","+english;
    	}
    }
    class StudentInforTool
    {
    	public static Set<Student> getStudents()throws IOException{
    		return getStudents(null);
    	}
    	public static Set<Student> getStudents(Comparator<Student> comp) throws IOException{
    		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
    		String line=null;
    		Set<Student> stus=new TreeSet<Student>();
    		if(comp==null){
    			stus=new TreeSet<Student>();
    		}else{
    			stus=new TreeSet<Student>(comp);
    		}
    		while((line=br.readLine())!=null){
    			if("over".equals(line))  
    				break;
    			String[] info=line.split(",");
    			Student stu=new Student(info[0],Double.parseDouble(info[1]),
    				Double.parseDouble(info[2]),Double.parseDouble(info[3]));
    			stus.add(stu);
    
    		}
    		return stus;
    	}
    	public static void writeStudents(Set<Student> stus)throws IOException{
    		BufferedWriter bw=new BufferedWriter(new FileWriter("student.txt"));
    		
    		for(Student stu:stus){
    			bw.write(stu.toString()+"\t\t");
    			bw.write(stu.getSum()+"");
    			bw.newLine();
    			bw.flush();
    		}
    		bw.close();
    	}
    }
    class StuScore
    {
    	public static void main(String[] args) throws IOException
    	{
    		Comparator<Student> comp=Collections.reverseOrder();
    		Set<Student> stus=StudentInforTool.getStudents(comp);
    		StudentInforTool.writeStudents(stus);
    	}
    }

【输出截图】：

键盘录入：

![20190626194420924.png][]

文件输出：

![2019062619444292.png][]

[20190626194420924.png]: /images/20210811/9ee8463805cc4377b33ce2b7e7aeb259.png
[2019062619444292.png]: /images/20210811/c69e676e518448dd93391b1e2df7ad32.png