有两道java编程题，因为我是学数据库的，很多java没接触过，求答案

public class Circle {

protected double r

public Circle(double r){

this.r=r

}

public Circle(){

this.r=10

}

public double area(){

double area=0

double r=this.r

area=3.14*r*r

return area

}

public double perimeter(){

double per=0

double r=this.r

per=3.14*2*r

return per

}

}

public class PlainCircle extends Circle

{

double cX,cY

public PlainCircle(double cX,double cY,double r) {

this.r=r

this.cX=cX

this.cY=cY

}

public PlainCircle() {

this.cX=0

this.cY=0

this.r=10

}

public boolean isInside(double x,double y){

if((x-cX)*(x-cX)+(y-cY)*(y-cY)<=r*r ){

return true

}

else

return false

}

}

//把你的那个表作成test3.txt放到D盘根，跑程序就好了

import java.io.BufferedReader

import java.io.FileInputStream

import java.io.InputStreamReader

import java.util.ArrayList

import java.util.Collections

import java.util.Iterator

import java.util.List

public class MyTest3 {

List stuInfoList = new ArrayList()

public MyTest3(){

printResult()

}

public void readFile() {

try {

BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("d:\\test3.txt")))

String line = ""

int i=0

while ((line = br.readLine()) != null) {

if(i++>0){ //略过头上的汉字行

StudentInfo student = new StudentInfo(line.split(" "))

stuInfoList.add(student)

}

}

} catch (Exception e) {

e.printStackTrace()

}

}

class StudentInfo implements Comparable{

public int stuId

public double pings

public double qizhong

public double qimo

public double bishi

public double zhongFeng

public StudentInfo(){}

public StudentInfo(String[] info){

this.stuId = Integer.parseInt(info[0])

this.pings = Integer.parseInt(info[1])

this.qizhong = Integer.parseInt(info[2])

this.qimo = Integer.parseInt(info[3])

this.bishi = Integer.parseInt(info[4])

this.zhongFeng = pings*0.1+qizhong*0.25+qimo*0.15+bishi*0.5

}

public String getPingJunFeng(int size){

return pings/size +" "+qizhong/size+" "+qimo/size+" "+bishi/size+" "+zhongFeng/size

}

public String toString(){

return stuId + " " +pings + " "+qizhong+" "+qimo+" "+bishi+" "+zhongFeng

}

public int compareTo(Object arg0) {

StudentInfo info = (StudentInfo)arg0

return (int)(info.zhongFeng-this.zhongFeng)

}

}

public void printResult(){

readFile()

System.out.println("学号 平时 期中 期末 笔试 总评分")

for(Iterator it=stuInfoList.iterator()it.hasNext()){

System.out.println(it.next())

}

System.out.println("-----------80分以上---------------\r\n学号 总评分")

for(Iterator it=stuInfoList.iterator()it.hasNext()){

StudentInfo info = (StudentInfo)it.next()

if(info.zhongFeng>=80)

System.out.println(info.stuId + " "+info.zhongFeng)

}

System.out.println("-----------没有及格---------------\r\n学号 总评分")

for(Iterator it=stuInfoList.iterator()it.hasNext()){

StudentInfo info = (StudentInfo)it.next()

if(info.zhongFeng<60)

System.out.println(info.stuId + " "+info.zhongFeng)

}

Collections.sort(stuInfoList)

System.out.println("-----------排序之后---------------\r\n学号 平时 期中 期末 笔试 总评分")

for(Iterator it=stuInfoList.iterator()it.hasNext()){

System.out.println(it.next())

}

StudentInfo pinjunfeng = new StudentInfo()

for(Iterator it=stuInfoList.iterator()it.hasNext()){

StudentInfo info = (StudentInfo)it.next()

pinjunfeng.bishi+=info.bishi

pinjunfeng.pings+=info.pings

pinjunfeng.qimo+=info.qimo

pinjunfeng.qizhong+=info.qizhong

pinjunfeng.zhongFeng+=info.zhongFeng

}

System.out.println("-----------平均分---------------\r\n平时 期中 期末 笔试 总评分")

System.out.println(pinjunfeng.getPingJunFeng(stuInfoList.size()))

}

public static void main(String[] args) throws Exception {

new MyTest3()

}

}

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