Scala文件读写——成绩分析

根据文件解决下例问题

1.读入txt文件：按行读入

import scala.io.Sourceobject Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()it.next()//跳过第一行while (it.hasNext){println(it.next())}source.close()}
}

2.处理数据：

（1）计算每个同学的总分和平均分

import scala.collection.mutable.ListBuffer
import scala.io.Source
case class Student(name: String, yuwen: Double, shuxue: Double, yingyu: Double, total: Double, avg: Double)
//案例分析：统计成绩
object Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//可变List，保存索引的学生数据val studentList = ListBuffer[Student]()//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()//迭代器it.next()//跳过第一行while (it.hasNext){val arr = it.next().split(",")//中文的逗号val name = arr(0)val yuwen = arr(1).toDoubleval shuxue = arr(2).toDoubleval yingyu = arr(3).toDoubleval total = yuwen + shuxue +yingyu //计算总分val avg = total / 3  //计算平均分//println(name,yuwen,shuxue,yingyu,total,avg)val s = Student(name,yuwen,shuxue,yingyu,total,avg)studentList +=s}source.close()studentList.foreach(println)}
}

（2）每个科目的平均分

import scala.collection.mutable.ListBuffer
import scala.io.Source
case class Student(name: String, yuwen: Double, shuxue: Double, yingyu: Double, total: Double, avg: Double)
//案例分析：统计成绩
object Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//可变List，保存索引的学生数据val studentList = ListBuffer[Student]()//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()//迭代器it.next()//跳过第一行while (it.hasNext){val arr = it.next().split("，")//中文的逗号val name = arr(0)val yuwen = arr(1).toDoubleval shuxue = arr(2).toDoubleval yingyu = arr(3).toDoubleval total = yuwen + shuxue +yingyu //计算总分val avg = total / 3  //计算平均分//println(name,yuwen,shuxue,yingyu,total,avg)val s = Student(name,yuwen,shuxue,yingyu,total,avg)studentList +=s}source.close()//计算单科总分var avgYuwen:Double = 0var avgShuxue:Double = 0var avgYingyu:Double = 0studentList.foreach(s=>{avgYuwen += s.yuwenavgShuxue += s.shuxueavgYingyu +=s.yingyu})println("语文平均分",avgYuwen/studentList.length)println("数学平均分",avgShuxue/studentList.length)println("英语平均分",avgYingyu/studentList.length)}
}

（3）总分前三名

import scala.collection.mutable.ListBuffer
import scala.io.Source
case class Student(name: String, yuwen: Double, shuxue: Double, yingyu: Double, total: Double, avg: Double)
//案例分析：统计成绩
object Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//可变List，保存索引的学生数据val studentList = ListBuffer[Student]()//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()//迭代器it.next()//跳过第一行while (it.hasNext){val arr = it.next().split("，")//中文的逗号val name = arr(0)val yuwen = arr(1).toDoubleval shuxue = arr(2).toDoubleval yingyu = arr(3).toDoubleval total = yuwen + shuxue +yingyu //计算总分val avg = total / 3  //计算平均分//println(name,yuwen,shuxue,yingyu,total,avg)val s = Student(name,yuwen,shuxue,yingyu,total,avg)studentList +=s}source.close()//计算单科总分var avgYuwen:Double = 0var avgShuxue:Double = 0var avgYingyu:Double = 0studentList.foreach(s=>{avgYuwen += s.yuwenavgShuxue += s.shuxueavgYingyu +=s.yingyu})println("语文平均分",avgYuwen/studentList.length)println("数学平均分",avgShuxue/studentList.length)println("英语平均分",avgYingyu/studentList.length)//总分前三名//思路：1.对所有的同学按总分从高到低排名val list1 =studentList.sortWith((a,b)=>a.total > b.total).slice(0,3)println("总分从高到低排名前三：")list1.foreach(println)}
}

（4）单科的前三名

package scala_mianximport scala.collection.mutable.ListBuffer
import scala.io.Source
case class Student(name: String, yuwen: Double, shuxue: Double, yingyu: Double, total: Double, avg: Double)
//案例分析：统计成绩
object Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//可变List，保存索引的学生数据val studentList = ListBuffer[Student]()//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()//迭代器it.next()//跳过第一行while (it.hasNext){val arr = it.next().split("，")//中文的逗号val name = arr(0)val yuwen = arr(1).toDoubleval shuxue = arr(2).toDoubleval yingyu = arr(3).toDoubleval total = yuwen + shuxue +yingyu //计算总分val avg = total / 3  //计算平均分//println(name,yuwen,shuxue,yingyu,total,avg)val s = Student(name,yuwen,shuxue,yingyu,total,avg)studentList +=s}source.close()//计算单科总分var avgYuwen:Double = 0var avgShuxue:Double = 0var avgYingyu:Double = 0studentList.foreach(s=>{avgYuwen += s.yuwenavgShuxue += s.shuxueavgYingyu +=s.yingyu})println("语文平均分",avgYuwen/studentList.length)println("数学平均分",avgShuxue/studentList.length)println("英语平均分",avgYingyu/studentList.length)//总分前三名//思路：1.对所有的同学按总分从高到低排名val list1 =studentList.sortWith((a,b)=>a.total > b.total).slice(0,3)println("总分从高到低排名前三：")list1.foreach(println)//单科成绩前三名//语文成绩前三名val list2 = studentList.sortWith((a,b)=> a.yuwen>b.yuwen).slice(0,3)println("语文总分从高到低排名前三：")list2.foreach(println)//数学成绩前三名val list3 = studentList.sortWith((a,b)=> a.shuxue>b.shuxue).slice(0,3)println("数学总分从高到低排名前三：")list3.foreach(println)//英语成绩前三名val list4 = studentList.sortWith((a,b)=> a.yingyu>b.yingyu).slice(0,3)println("英语总分从高到低排名前三：")list4.foreach(println)}
}

3.把结果写入文件

package scala_mianximport java.io.PrintWriter
import scala.collection.mutable.ListBuffer
import scala.io.Source
case class Student(name: String, yuwen: Double, shuxue: Double, yingyu: Double, total: Double, avg: Double)
//案例分析：统计成绩
object Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//可变List，保存索引的学生数据val studentList = ListBuffer[Student]()//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()//迭代器it.next()//跳过第一行while (it.hasNext){val arr = it.next().split("，")//中文的逗号val name = arr(0)val yuwen = arr(1).toDoubleval shuxue = arr(2).toDoubleval yingyu = arr(3).toDoubleval total = yuwen + shuxue +yingyu //计算总分val avg = total / 3  //计算平均分//println(name,yuwen,shuxue,yingyu,total,avg)val s = Student(name,yuwen,shuxue,yingyu,total,avg)studentList +=s}source.close()//计算单科总分var avgYuwen:Double = 0var avgShuxue:Double = 0var avgYingyu:Double = 0studentList.foreach(s=>{avgYuwen += s.yuwenavgShuxue += s.shuxueavgYingyu +=s.yingyu})println("语文平均分",avgYuwen/studentList.length)println("数学平均分",avgShuxue/studentList.length)println("英语平均分",avgYingyu/studentList.length)//总分前三名//思路：1.对所有的同学按总分从高到低排名val list1 =studentList.sortWith((a,b)=>a.total > b.total).slice(0,3)println("总分从高到低排名前三：")list1.foreach(println)//单科成绩前三名//语文成绩前三名val list2 = studentList.sortWith((a,b)=> a.yuwen>b.yuwen).slice(0,3)println("语文总分从高到低排名前三：")list2.foreach(println)//数学成绩前三名val list3 = studentList.sortWith((a,b)=> a.shuxue>b.shuxue).slice(0,3)println("数学总分从高到低排名前三：")list3.foreach(println)//英语成绩前三名val list4 = studentList.sortWith((a,b)=> a.yingyu>b.yingyu).slice(0,3)println("英语总分从高到低排名前三：")list4.foreach(println)//写入文件val writer=new PrintWriter("统计成绩的结果")writer.println("姓名，语文，数学，英语，总分，平均分")studentList.foreach(s =>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.total},${avg}")})writer.println("-"*40)writer.close()  //关闭文件}
}

代码整合

import java.io.PrintWriter
import scala.collection.mutable.ListBuffer
import scala.io.Sourcecase class Student(name: String, yuwen: Double, shuxue: Double, yingyu: Double, total: Double, avg: Double)//案例分析：统计成绩
object Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//可变List，保存索引的学生数据val studentList = ListBuffer[Student]()//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()//迭代器it.next()//跳过第一行while (it.hasNext){val arr = it.next().split("，")//中文的逗号val name = arr(0)val yuwen = arr(1).toDoubleval shuxue = arr(2).toDoubleval yingyu = arr(3).toDoubleval total = yuwen + shuxue +yingyu //计算总分val avg = total / 3  //计算平均分//println(name,yuwen,shuxue,yingyu,total,avg)val s = Student(name,yuwen,shuxue,yingyu,total,avg)studentList +=s}source.close()//计算单科总分var avgYuwen:Double = 0var avgShuxue:Double = 0var avgYingyu:Double = 0studentList.foreach(s=>{avgYuwen += s.yuwenavgShuxue += s.shuxueavgYingyu +=s.yingyu})println("语文平均分",avgYuwen/studentList.length)println("数学平均分",avgShuxue/studentList.length)println("英语平均分",avgYingyu/studentList.length)//总分前三名//思路：1.对所有的同学按总分从高到低排名val list1 =studentList.sortWith((a,b)=>a.total > b.total).slice(0,3)println("总分从高到低排名前三：")list1.foreach(println)//单科成绩前三名//语文成绩前三名val list2 = studentList.sortWith((a,b)=> a.yuwen>b.yuwen).slice(0,3)println("语文总分从高到低排名前三：")list2.foreach(println)//数学成绩前三名val list3 = studentList.sortWith((a,b)=> a.shuxue>b.shuxue).slice(0,3)println("数学总分从高到低排名前三：")list3.foreach(println)//英语成绩前三名val list4 = studentList.sortWith((a,b)=> a.yingyu>b.yingyu).slice(0,3)println("英语总分从高到低排名前三：")list4.foreach(println)//写入文件val writer=new PrintWriter("统计成绩的结果")writer.println("姓名，语文，数学，英语，总分，平均分")studentList.foreach(s =>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.total},${avg}")})writer.println("-"*40)//总分前三名list1.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.total},${avg}")})writer.println("-"*40)//语文前三名list2.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.total},${avg}")})writer.println("-"*40)//数学前三名list3.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.total},${avg}")})writer.println("-"*40)//英语前三名list4.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.total},${avg}")})writer.println("-"*40)writer.close()  //关闭文件}
}

运行结果：

任务说明

在本课内容的基础上，补充两门新课（Java，scala）的成绩，并完成

1.总分和平均分的计算

2.单科成绩的前5名排名

3.每个学生的在班级的整体排名

import java.io.PrintWriter
import scala.collection.mutable.ListBuffer
import scala.io.Source
case class Student(name: String, yuwen: Double, shuxue: Double, yingyu: Double,java:Double,scala:Double, total: Double, avg: Double)
//案例分析：统计成绩
object Test文件读写_成绩分析 {def main(args: Array[String]): Unit = {//可变List，保存索引的学生数据val studentList = ListBuffer[Student]()//1.按行读入val source = Source.fromFile("score.txt")val it = source.getLines()//迭代器it.next()//跳过第一行while (it.hasNext){val arr = it.next().split("，")//中文的逗号val name = arr(0)val yuwen = arr(1).toDoubleval shuxue = arr(2).toDoubleval yingyu = arr(3).toDoubleval java = arr(4).toDoubleval scala = arr(5).toDoubleval total = yuwen + shuxue +yingyu //计算总分val avg = total / 5  //计算平均分//println(name,yuwen,shuxue,yingyu,total,avg)val s = Student(name,yuwen,shuxue,yingyu,java,scala,total,avg)studentList +=s}source.close()//计算单科总分var avgYuwen:Double = 0var avgShuxue:Double = 0var avgYingyu:Double = 0var avgJava:Double = 0var avgScala:Double = 0studentList.foreach(s=>{avgYuwen += s.yuwenavgShuxue += s.shuxueavgYingyu +=s.yingyuavgJava +=s.javaavgScala +=s.scala})println("语文平均分",avgYuwen/studentList.length)println("数学平均分",avgShuxue/studentList.length)println("英语平均分",avgYingyu/studentList.length)println("java平均分",avgJava/studentList.length)println("scala平均分",avgScala/studentList.length)//总分前三名//思路：1.对所有的同学按总分从高到低排名val list1 =studentList.sortWith((a,b)=>a.total > b.total).slice(0,3)println("总分从高到低排名前三：")list1.foreach(println)//单科成绩前三名//语文成绩前三名val list2 = studentList.sortWith((a,b)=> a.yuwen>b.yuwen).slice(0,3)println("语文总分从高到低排名前3：")list2.foreach(println)//数学成绩前三名val list3 = studentList.sortWith((a,b)=> a.shuxue>b.shuxue).slice(0,3)println("数学总分从高到低排名前三：")list3.foreach(println)//英语成绩前三名val list4 = studentList.sortWith((a,b)=> a.yingyu>b.yingyu).slice(0,3)println("英语总分从高到低排名前三：")list4.foreach(println)//java成绩前5名val list5 = studentList.sortWith((a,b)=> a.java>b.java).slice(0,5)println("英语总分从高到低排名前三：")list4.foreach(println)//scala成绩前5名val list6 = studentList.sortWith((a,b)=> a.scala>b.scala).slice(0,5)println("英语总分从高到低排名前三：")list4.foreach(println)//写入文件val writer=new PrintWriter("统计成绩的结果")writer.println("姓名，语文，数学，英语，java,scala总分，平均分")studentList.foreach(s =>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.java},${s.scala},${s.total},${avg}")})writer.println("-"*40)//总分前三名list1.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.java},${s.scala},${s.total},${avg}")})writer.println("-"*40)//语文前三名list2.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.java},${s.scala},${s.total},${avg}")})writer.println("-"*40)//数学前三名list3.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.java},${s.scala},${s.total},${avg}")})writer.println("-"*40)//英语前三名list4.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.java},${s.scala},${s.total},${avg}")})writer.println("-"*40)//java前三名list5.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.java},${s.scala},${s.total},${avg}")})writer.println("-"*40)//scala前三名list6.foreach(s=>{val avg =String.format("%.1f",s.avg)  //只保留一位有效数字writer.println(s"${s.name},${s.yuwen},${s.shuxue},${s.yingyu},${s.java},${s.scala},${s.total},${avg}")})writer.println("-"*40)writer.close()  //关闭文件}
}