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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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