按班级统计学生的平均成绩时，为了减少工作量，计划使用计算机来做这样的统计工作。
下面给出一个类Score用来表示每条考试成绩。
代码语言：javascript复制package com.test;
/**
* 学生成绩。
*/
class Score {
/**
* 学生姓名。
*/
public String stdName;
/**
* 班级号。
*/
public String classNumber;
/**
* 分数。
*/
public int mark;
public String getStdName() {
return stdName;
}
public void setStdName(String stdName) {
this.stdName = stdName;
}
public String getClassNumber() {
return classNumber;
}
public void setClassNumber(String classNumber) {
this.classNumber = classNumber;
}
public int getMark() {
return mark;
}
public void setMark(int mark) {
this.mark = mark;
}
}编写一个类ScoreStatistic，在类里实现以下方法：
代码语言：javascript复制package com.test;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class ScoreStatistic{
public ScoreStatistic(){
}
public Map<String,Integer> statistic1(List<Score> scores){
Map<String,Integer> classcountMap = new HashMap<String, Integer>();
Map<String,Integer> classsumMap = new HashMap<String, Integer>();
Iterator<Score> it = scores.iterator();
while (it.hasNext()) {
Score temp = it.next();
String cn = temp.classNumber;
int cm = temp.mark;
// System.out.println(it.next().classNumber " " it.next().mark);
if(classcountMap.get(cn)!=null){System.out.println("1");
classcountMap.put(cn, classcountMap.get(cn) 1);
classsumMap.put(cn, classsumMap.get(cn) cm);
}else{
classcountMap.put(cn, 1);
classsumMap.put(cn,cm);
}
}
Map<String, Integer> finalMap = new HashMap<String, Integer>();
Iterator it1=classcountMap.keySet().iterator();
while(it1.hasNext()){
String key;
Integer value;
Integer marksum;
key=it1.next().toString();
value=classcountMap.get(key);
marksum=classsumMap.get(key); System.out.println(value);
finalMap.put(key, marksum/value);
System.out.println(key ":" marksum/value);
}
return classsumMap;
}
public Map<String,Integer> statistic(List<Score> scores){
Map<String,Integer> map = new HashMap<String,Integer>();
Map<String,ClassRoom> roomMap = new HashMap<String,ClassRoom>();
int avg;
ClassRoom room = null;
for(Score score:scores){
String classNumber = score.getClassNumber();
int mark = score.getMark();
room = roomMap.get(classNumber);
if(room == null){
room = new ClassRoom(classNumber);
roomMap.put(classNumber, room);
}
room.setTotal(room.getTotal() mark);
room.getList().add(score);
//System.out.println(score.getClassNumber() ":" avg);
}
Set<Map.Entry<String,ClassRoom>> set = roomMap.entrySet();
Iterator<Map.Entry<String, ClassRoom>> it = set.iterator();
while(it.hasNext()){
Map.Entry<String, ClassRoom> entry = it.next();
ClassRoom ro = entry.getValue();
avg = ro.getTotal()/ro.getList().size();
map.put(ro.getClassNumber(), avg);
System.out.println(ro.getClassNumber() ":" avg);
}
return map;
}
class ClassRoom{
/**
* 班级号。
*/
public String classNumber;
/**
* 总分
*/
private int total;
private List<Score> list;
public ClassRoom(){
list = new ArrayList<Score>();
}
public ClassRoom(String classNumber){
this();
this.classNumber = classNumber;
}
public String getClassNumber() {
return classNumber;
}
public void setClassNumber(String classNumber) {
this.classNumber = classNumber;
}
public int getTotal() {
return total;
}
public void setTotal(int total) {
this.total = total;
}
public List<Score> getList() {
return list;
}
public void setList(List<Score> list) {
this.list = list;
}
}
}
