将本班学生的信息（每个学生至少包括学号、姓名、科目成绩（至少两门）、学分、平均分），存放于文件stduent.txt中。
A．要求编写函数fun1对10个学生按某科成绩升序或降序（可选择）排序，并将结果（包括名次、学号、姓名、成绩、学分、平均分）存放于文件score.txt中。
B．编写函数fun2，用二分法查找score.txt中某科某个成绩，并将结果打印出来。-------->以上是要求，可是我学得不好，处理名字啊，成绩啊什么的总是空指针错误或者其他错误，而且文件也不会啊，哪位高手能帮帮我呢？期末要交了！
A．要求编写函数fun1对10个学生按某科成绩升序或降序（可选择）排序，并将结果（包括名次、学号、姓名、成绩、学分、平均分）存放于文件score.txt中。
B．编写函数fun2，用二分法查找score.txt中某科某个成绩，并将结果打印出来。-------->以上是要求，可是我学得不好，处理名字啊，成绩啊什么的总是空指针错误或者其他错误，而且文件也不会啊，哪位高手能帮帮我呢？期末要交了！
先readline,再对每行的数据进行分析。用stringtokenizer去做
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
public class TextClass {
public static void main(String[] args) {
fun1();
Student student = fun2(98);
System.out.println(student.getName());
}
public static void fun1(){
List<Student> studentList = new ArrayList<Student>();
try {
BufferedReader in = new BufferedReader(
new InputStreamReader(
new FileInputStream("student.txt"),"utf-8"));
String str;
while((str = in.readLine())!=null){
if(str.startsWith("#")){
continue;
}
System.out.println(str);
String[] strs = str.split(":");
//这里不习惯用数组来做，所以定义了一个学生信息类,在下面。
Student student = new Student();
student.setId(strs[0]);
student.setName(strs[1]);
student.setScore1(Integer.parseInt(strs[2]));
student.setScore2(Integer.parseInt(strs[3]));
student.setCredit(Integer.parseInt(strs[4]));
student.setAvgScore(Double.parseDouble(strs[5]));
studentList.add(student);
}
Collections.sort(studentList, new Comparator<Student>() {
@Override
public int compare(Student o1, Student o2) {
return o1.getScore1()-o2.getScore1();
//用语文成绩进行比较。
}
});
PrintWriter out = new PrintWriter(
new OutputStreamWriter(
new BufferedOutputStream(
new FileOutputStream("score.txt")), "utf-8"));
for(Student student:studentList){
int i = 1;
String scoreStr = "第"+ i++ + "名"+ ":"+student.getId()+":"
+student.getName()+":"+student.getScore1()+":"+student.getScore2()
+":"+student.getCredit()+":"+student.getAvgScore();
out.println(scoreStr);
out.flush();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
//des 为要查找的分数 找到之后你要干嘛你自己做写吧
public static Student fun2(int des){
//从score.txt中读取成绩等信息以便进行二分查找****************
List<Student> studentList = new ArrayList<Student>();
try {
BufferedReader in = new BufferedReader(
new InputStreamReader(
new FileInputStream("score.txt"),"utf-8"));
String str;
while((str = in.readLine())!=null){
if(str.startsWith("#")){
continue;
}
String[] strs = str.split(":");
Student student = new Student();
student.setId(strs[1]);
student.setName(strs[2]);
student.setScore1(Integer.parseInt(strs[3]));
student.setScore2(Integer.parseInt(strs[4]));
student.setCredit(Integer.parseInt(strs[5]));
student.setAvgScore(Double.parseDouble(strs[6]));
studentList.add(student);
}
//开始进行二分查找**************************
int low = 0;
int high = studentList.size()-1;
while(low <= high) {
int middle = (low + high)/2;
if(des == studentList.get(middle).getScore1()) {
return studentList.get(middle);
}else if(des <studentList.get(middle).getScore1()) {
high = middle - 1;
}else {
low = middle + 1;
}
}
return null;
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}class Student{
private String id;
private String name;
private int score1;//语文成绩
private int score2;//数学成绩
private int credit;//学分
private double avgScore;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getScore1() {
return score1;
}
public void setScore1(int score1) {
this.score1 = score1;
}
public int getScore2() {
return score2;
}
public void setScore2(int score2) {
this.score2 = score2;
}
public int getCredit() {
return credit;
}
public void setCredit(int credit) {
this.credit = credit;
}
public double getAvgScore() {
return avgScore;
}
public void setAvgScore(double avgScore) {
this.avgScore = avgScore;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((id == null) ? 0 : id.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Student other = (Student) obj;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
return true;
}
}