Scala學習(九)練習

時間 2019-11-12

標籤 scala 學習練習欄目 Scala 简体版

原文原文鏈接

文件正則表達式&練習java

1. 編寫一小段Scala代碼，將某個文件中的行倒轉順序，將最後一行做爲第一行,依此類推正則表達式

程序代碼:數組

import scala.io.Source
import java.io.PrintWriter
object ReverseLines extends App {
val filename="File.txt"
val RefileName="ReverseFile.txt"
val source=Source.fromFile("src\\"+filename)
lazy val ReSource=Source.fromFile("src\\"+RefileName)
lazy val pw = new PrintWriter("src\\"+RefileName)
val linesIterator=source.getLines()
val linesRecord=linesIterator.toArray
val reverseRecord=linesRecord.reverse
reverseRecord.foreach {
line =>pw.write(line+"\n")
}
pw.close()
println(filename+" 文件內容以下: ")
linesRecord.foreach (line=>println(line))
println(RefileName+" 文件內容以下: ")
ReSource.getLines().foreach(line=>println(line))
}

運行結果:ide

File.txt文件內容以下: 測試

Inc said they plan to form a venture to manage the money market this

borrowing and investment activities of both companies. spa

BP North America is a subsidiary of British Petroleum Co scala

Plc <BP>, which also owns a 55 pct interest in Standard Oil. rest

The venture will be called BP/Standard Financial Trading orm

and will be operated by Standard Oil under the oversight of a

joint management committee.

ReverseFile.txt文件內容以下:

joint management committee.

and will be operated by Standard Oil under the oversight of a

The venture will be called BP/Standard Financial Trading

Plc <BP>, which also owns a 55 pct interest in Standard Oil.

BP North America is a subsidiary of British Petroleum Co

borrowing and investment activities of both companies.

Inc said they plan to form a venture to manage the money market

2. 編寫Scala程序，從一個帶有製表符的文件讀取內容，將每一個製表符替換成一組空格，使得製表符隔開的n列仍然保持縱向對齊，並將結果寫入同一個文件

程序代碼:

object TabSpace extends App{
val FileName="TabSpace"
val path="src\\"+FileName+".txt"
val linesIterator=Source.fromFile(path).getLines()
lazy val TabIterator=Source.fromFile(path).getLines()
val linesRecord=linesIterator.toArray
lazy val pw=new PrintWriter(path)
println(FileName+" 文件內容以下: ")
linesRecord.foreach(println)
linesRecord.foreach {
line =>pw.write(line.replaceAll("\t", "")+"\n")
}
pw.close
println(" 替換後 "+FileName+" 文件內容以下: ")
TabIterator.foreach(println)
}

運行結果:

TabSpace文件內容以下:

Inc    said    they    plan    to    form    a    venture    to    manage    the    money    market

Inc    ssss    adfs    sdjf    sd    dskl    s    jdakwus    sd    sdskkl    sds    sdsds    djslkl

Inc    said    they    plan    to    form    a    venture    to    manage    the    money    market

Inc    ssss    adfs    sdjf    sd    dskl    s    jdakwus    sd    sdskkl    sds    sdsds    djslkl

Inc    said    they    plan    to    form    a    venture    to    manage    the    money    market

替換後TabSpace文件內容以下:

Inc said they plan to form a venture to manage the money market

Inc ssss adfs sdjf sd dskl s jdakwus sd sdskkl sds sdsds djslkl

Inc said they plan to form a venture to manage the money market

Inc ssss adfs sdjf sd dskl s jdakwus sd sdskkl sds sdsds djslkl

Inc said they plan to form a venture to manage the money market

3. 編寫一小段Scala代碼，從一個文件讀取內容並把全部字符數大於12的單詞打印到控制檯。若是你能用單行代碼完成會有額外獎勵

程序代碼：

object CheckString extends App{
val FileName="CheckString"
val path="src\\"+FileName+".txt"
println(FileName+" 文件中長度大於12的字符串爲: ")
io.Source.fromFile(path).mkString.split("\\s+").foreach (str => if(str.length()>12) println(str))
}

運行結果：

CheckString文件中長度大於12的字符串爲:

Incsaidtheyplan

jdakwussdsdskkl

managethemoneymarket

dsklsjdakwussdsdskkl

venturetomanagethe

4. 編寫Scala程序，從包含浮點數的文本文件讀取內容，打印出文件中全部浮點數之和，平均值，最大值和最小值

程序代碼：

object ReadNumber extends App{
val pattern=" (\\d+[.]\\d+)".r
val pattern1=" ^\\d+(\\.\\d+)?".r
val pattern2=" [0-9]+(\\.\\d+)?".r
val FileName=" NumberFile"
val path = " src\\"+FileName+" .txt"
val FileStr=io.Source.fromFile(path).mkString
val StrArray=pattern2.findAllIn(FileStr).toArray
var total=0d
val len=StrArray.length
StrArray.foreach (total +=_.toDouble)
println(" 文本中浮點數總和: "+total)
println(" 文本中浮點數平均數: "+total/len+len)
println(" 文本中浮點數的最大值: "+StrArray.max)
println(" 文本中浮點數的最大值: "+StrArray.min)
}

測試數據：

joint    55    666.0    management    13.5    committee    12.5

joint    6.0    123.4    management    3.14    committee    170.5

joint    52    63.32    management    10.4    committee    12.5

運行結果：

文本中浮點數總和: 1188.26

文本中浮點數平均數: 99.0216666666666612

文本中浮點數的最大值: 666.0

文本中浮點數的最大值: 10.4

5. 編寫Scala程序，向文件中寫入2的n次方及其倒數，指數n從0到20。對齊各列:

1 1

2 0.5

4 0.25

... ...

程序代碼：

import java.io.PrintWriter
object index extends App{
val FileName="Index"
val path="src\\"+FileName+".txt"
val out=new PrintWriter(path)
for (i <- 0 to 20)
out.println(OutIndex(i))
out.close
def OutIndex(n:Int)={
val value=math.pow(2, n)
""*4+value.toInt+""*(11-value.toString().size)+math.pow(2, -n)
}
}

運行結果：

1 1.0

2 0.5

4 0.25

8 0.125

16 0.0625

32 0.03125

64 0.015625

128 0.0078125

256 0.00390625

512 0.001953125

1024 9.765625E-4

2048 4.8828125E-4

4096 2.44140625E-4

8192 1.220703125E-4

16384 6.103515625E-5

32768 3.0517578125E-5

65536 1.52587890625E-5

131072 7.62939453125E-6

262144 3.814697265625E-6

524288 1.9073486328125E-6

1048576 9.5367431640625E-7

6. 編寫正則表達式，匹配Java或C++程序代碼中相似"like this，maybe with \" or\\"這樣的帶引號的字符串。編寫Scala程序將某個源文件中全部相似的字符串打印出來

描述：沒看太懂，按本身意思來的

程序代碼：

import scala.io.Source
object regExp extends App{
val FileName="Regexp"
val path="src\\"+FileName+".txt"
val pat1=""""like this ， maybe with \\" or\\{2}"""".r
val pat2="""like this ， maybe with \\" or\\{2}""".r
val pat3="""\w+\s+\\"""".r
val linesIterator1=Source.fromFile(path).getLines()
val linesIterator2=Source.fromFile(path).getLines()
val linesIterator3=Source.fromFile(path).getLines()
println(" 文本中包含: "+""""like this ， maybe with \" or\\"""")
linesIterator1.foreach(line=>pat1.findAllIn(line).foreach (println))
println(" 文本中包含: "+"""like this ， maybe with \" or\\""")
linesIterator2.foreach(line=>pat2.findAllIn(line).foreach (println))
println(" 文本中包含: "+"\\w+\\s+\"")
linesIterator3.foreach(line=>pat3.findAllIn(line).foreach(println))
}

運行結果：

文本中包含:"like this，maybe with \" or\\"

"like this，maybe with \" or\\"

文本中包含:like this，maybe with \" or\\

like this，maybe with \" or\\

like this，maybe with \" or\\

like this，maybe with \" or\\

文本中包含:\w+\s+"

with \"

with \"

with \"

7. 編寫Scala程序，從文本文件讀取內容，並打印出全部的非浮點數的詞法單位。要求使用正則表達式

程序代碼：

import io.Source
object NonFloat extends App{
val source = Source.fromFile("src\\NumberFile.txt").mkString
val pat1 = """[^((\d+\.){0,1}\d+)^\s+]+$""".r// 去掉 +試試
val pat2 = """^((?!^[-]?\d*\.\d+$).)+$""".r
println(" 模式1不包含整數: ")
for(token <- source.split("\\s+")){
for(word <- pat1.findAllIn(token))
if(!word.equals("")){
println(token)
}
}
println(" 模式2包含整數: ")
for(token <- source.split("\\s+")){
for(word <- pat2.findAllIn(token))
println(word)
}
}

測試數據：

joint    55    666.0    management    13.5    committee    12.5

joint    6.0    123.4    management    3.14    committee    170.5

joint    52    63.32    management    10.4    committee    12.5

0.12t    20    5.6ef    45.77ghjss    5.94    dfdxsccxz    7.9

運行結果：

模式1不包含整數:

joint

management

committee

joint

management

committee

joint

management

committee

0.12t

5.6ef

45.77ghjss

dfdxsccxz

模式2包含整數:

joint

55

management

committee

joint

management

committee

joint

52

management

committee

0.12t

20

5.6ef

45.77ghjss

dfdxsccxz

8. 編寫Scala程序打印出某個網頁中全部img標籤的src屬性。使用正則表達式和分組

程序代碼：

object WebSrc extends App{
val pat = """<img.*?src=[" '](.+?)["'].*?>""".r
for (pat(src) <-pat.findAllIn(io.Source.fromURL(" http://www.baidu.com").mkString)) {
println(src)
}
}

運行結果：

//www.baidu.com/img/bd_logo1.png

//www.baidu.com/img/baidu_jgylogo3.gif

9. 編寫Scala程序，盤點給定目錄及其子目錄中總共有多少以.class爲擴展名的文件

程序代碼：

import java.io.File
object NumDir extends App{
val path = " ."
val dir = new File(path)
def subdirs(dir:File):Iterator[File]={
val children = dir.listFiles().filter(_.getName.endsWith(" class"))
children.toIterator ++ dir.listFiles().filter(_.isDirectory).toIterator.flatMap(subdirs _)
}
val n = subdirs(dir).length
println(n)
}

運行結果：

52

10. 擴展那個可序列化的Person類，讓它能以一個集合保存某我的的朋友信息。構造出一些Person對象，讓他們中的一些人成爲朋友，而後將Array[Person]保存到文件。將這個數組從文件中從新讀出來，校驗朋友關係是否無缺注意,請在main中執行。腳本執行沒法序列化。

程序代碼：

import collection.mutable.ArrayBuffer
import java.io.{ObjectInputStream, FileOutputStream, FileInputStream, ObjectOutputStream}
class Person(var name:String) extends Serializable{
val friends = new ArrayBuffer[Person]()
def addFriend(friend : Person){
friends += friend
}
override def toString() = {
var str = "My name is " + name + " and my friends name is "
friends.foreach(str += _.name + ",")
str
}
}
object PersonTest extends App{
val p1 = new Person("JackChen")
val p2 = new Person("Jhon·D")
val p3 = new Person("Sunday")
p1.addFriend(p2)
p1.addFriend(p3)
println(p1)
val out = new ObjectOutputStream(new FileOutputStream("src\\Person.txt"))
out.writeObject(p1)
out.close()
val in = new ObjectInputStream(new FileInputStream("src\\Person.txt"))
val p = in.readObject().asInstanceOf[Person]
println(p)
}

運行結果：

My name is JackChen and my friends name is Jhon·D,Sunday,

My name is JackChen and my friends name is Jhon·D,Sunday,

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