在Java中如何从文本文件中找到单词的最大出现次数？

已发表: 2021-09-13
在Java中如何从文本文件中找到单词的最大出现次数？

在本 Java 教程中，您将学习如何从给定的文本文件中查找单词的最大出现次数？

这是获取顶级元素的逻辑：

  1. 创建一个CrunchifyComparable类，它可以存储单词的 String 值和它出现的次数。
  2. 为此类实现 Comparable 接口，先按sort by occurrences first and then alphabetically
  3. crunchifyFindMaxOccurrence方法，您可以从原始地图创建一个新的CrunchifyComparable列表。 您将此条目添加到您的列表中
  4. 排序此列表
  5. 使用 subList 获取此列表的第 n 个项目
  6. 将字符串添加到List<String>并返回它

Another most read的文章：查找有关 equals() 和 hashcode() 的更多信息

Java 代码：

创建类 CrunchifyFindMaxOccurrence.java。 将以下代码放入文件中。

Java
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package crunchify . com . tutorials ;
 
import java . io . * ;
import java . util . * ;
 
public class CrunchifyFindMaxOccurrence {
/**
* @author Crunchify.com
* In Java How to Find Maximum Occurrence of Words from Text File?
*/
public static void main ( String [ ] args ) throws FileNotFoundException , IOException {
// File: An abstract representation of file and directory pathnames.
// User interfaces and operating systems use system-dependent pathname strings to name files and directories.
// This class presents an abstract, system-independent view of hierarchical pathnames.
File file = new File ( "/Users/app/Download/crunchify.txt" ) ;
// BufferedReader: Reads text from a character-input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines.
// The buffer size may be specified, or the default size may be used.
// The default is large enough for most purposes.
BufferedReader bufferedReader = null ;
bufferedReader = new BufferedReader ( new FileReader ( file ) ) ;
String inputLine = null ;
// Map: An object that maps keys to values. A map cannot contain duplicate keys; each key can map to at most one value.
Map < String , Integer > crunchifyMap = new HashMap < > ( ) ;
try {
while ( ( inputLine = bufferedReader . readLine ( ) ) ! = null ) {
// split(): Splits this string around matches of the given regular expression.
// This method works as if by invoking the two-argument split method with the given expression and a limit argument of zero.
// Trailing empty strings are therefore not included in the resulting array.
String [ ] words = inputLine . split ( "[ \n\t\r.,;:!?(){}]" ) ;
for ( String word : words ) {
String key = word . toLowerCase ( ) ; // remove .toLowerCase for Case Sensitive result.
if ( key . length ( ) > 0 ) {
if ( crunchifyMap . get ( key ) == null ) {
crunchifyMap . put ( key , 1 ) ;
} else {
int value = crunchifyMap . get ( key ) . intValue ( ) ;
value ++ ;
crunchifyMap . put ( key , value ) ;
}
}
}
}
// Set: A collection that contains no duplicate elements.
// More formally, sets contain no pair of elements e1 and e2 such that e1.equals(e2),
// and at most one null element. As implied by its name, this interface models the mathematical set abstraction.
Set < Map . Entry < String , Integer > > entrySet = crunchifyMap . entrySet ( ) ;
crunchifyPrint ( "Words" + "\t\t" + "# of Occurances" ) ;
for ( Map . Entry < String , Integer > entry : entrySet ) {
crunchifyPrint ( entry . getKey ( ) + "\t\t" + entry . getValue ( ) ) ;
}
List <String> myTopOccurrence = crunchifyFindMaxOccurrence ( crunchifyMap , 1 ) ;
crunchifyPrint ( "\nMaximum Occurrence of Word in file: " ) ;
for ( String result : myTopOccurrence ) {
crunchifyPrint ( "==> " + result ) ;
}
// IOException: Signals that an I/O exception of some sort has occurred.
// This class is the general class of exceptions produced by failed or interrupted I/O operations.
} catch ( IOException error ) {
crunchifyPrint ( "Invalid File" ) ;
} finally {
bufferedReader . close ( ) ;
}
}
private static void crunchifyPrint ( String s ) {
System . out . println ( s ) ;
}
/**
* @param map = All Words in map
* @param n   = How many top elements you want to print? If n=1 it will print the highest occurrence word. If n=2 it
*            will print top 2 highest occurrence words.
* @returns list of String
*/
public static List <String> crunchifyFindMaxOccurrence ( Map < String , Integer > map , int n ) {
List <CrunchifyComparable> l = new ArrayList < > ( ) ;
for ( Map . Entry < String , Integer > entry : map . entrySet ( ) )
l . add ( new CrunchifyComparable ( entry . getKey ( ) , entry . getValue ( ) ) ) ;
// sort(): Sorts the specified list into ascending order, according to the natural ordering of its elements.
// All elements in the list must implement the Comparable interface. Furthermore, all elements in the list must be mutually comparable
// (that is, e1.compareTo(e2) must not throw a ClassCastException for any elements e1 and e2 in the list).
Collections . sort ( l ) ;
List <String> list = new ArrayList < > ( ) ;
// subList(): Returns a view of the portion of this list between the specified fromIndex,
// inclusive, and toIndex, exclusive. (If fromIndex and toIndex are equal, the returned list is empty.)
// The returned list is backed by this list, so non-structural changes in the returned list are reflected in this list, and vice-versa.
// The returned list supports all of the optional list operations supported by this list.
for ( CrunchifyComparable w : l . subList ( 0 , n ) )
list . add ( w . wordFromFile + ":" + w . numberOfOccurrence ) ;
return list ;
}
}
 
class CrunchifyComparable implements Comparable <CrunchifyComparable> {
public String wordFromFile ;
public int numberOfOccurrence ;
public CrunchifyComparable ( String wordFromFile , int numberOfOccurrence ) {
super ( ) ;
this . wordFromFile = wordFromFile ;
this . numberOfOccurrence = numberOfOccurrence ;
}
@Override
public int compareTo ( CrunchifyComparable arg0 ) {
int crunchifyCompare = Integer . compare ( arg0 . numberOfOccurrence , this . numberOfOccurrence ) ;
return crunchifyCompare ! = 0 ? crunchifyCompare : wordFromFile . compareTo ( arg0 . wordFromFile ) ;
}
@Override
public int hashCode ( ) {
final int uniqueNumber = 19 ;
int crunchifyResult = 9 ;
crunchifyResult = uniqueNumber * crunchifyResult + numberOfOccurrence ;
// hasCode(): Returns a hash code for this string. The hash code for a String object is computed as
//       s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
//
// using int arithmetic, where s[i] is the ith character of the string, n is the length of the string,
// and ^ indicates exponentiation. (The hash value of the empty string is zero.)
crunchifyResult = uniqueNumber * crunchifyResult + ( ( wordFromFile == null ) ? 0 : wordFromFile . hashCode ( ) ) ;
return crunchifyResult ;
}
// Override: Indicates that a method declaration is intended to override a method declaration in a supertype.
// If a method is annotated with this annotation type compilers are required
// to generate an error message unless at least one of the following conditions hold:
// The method does override or implement a method declared in a supertype.
// The method has a signature that is override-equivalent to that of any public method declared in Object.
@Override
public boolean equals ( Object crunchifyObj ) {
if ( this == crunchifyObj )
return true ;
if ( crunchifyObj == null )
return false ;
if ( getClass ( ) ! = crunchifyObj . getClass ( ) )
return false ;
CrunchifyComparable other = ( CrunchifyComparable ) crunchifyObj ;
if ( numberOfOccurrence ! = other . numberOfOccurrence )
return false ;
if ( wordFromFile == null ) {
if ( other . wordFromFile ! = null )
return false ;
} else if ( ! wordFromFile . equals ( other . wordFromFile ) )
return false ;
return true ;
}
}

示例 1 文件：

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Crunchify is the largest free , premium , technical & blogging resource site for beginners , who are passionate & have the desire to excel in the online world . Attracting over 16 million monthly users , we are leading & trusted tech + blogging resource for all . We also help clients transform their great ideas into reality !
 
Crunchify , Crunchify , Crunchify . com

输出：

这是一个 IntelliJ IDEA 控制台结果。 将上述程序作为 Java 应用程序运行，您将看到如下结果。

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/ Library / Java / JavaVirtualMachines / jdk - 15.jdk / Contents / Home / bin / java - javaagent : / Applications / IntelliJ IDEA . app / Contents / lib / idea_rt . jar = 50339 : / Applications / IntelliJ IDEA . app / Contents / bin - Dfile . encoding = UTF - 8
- classpath / Users / app / crunchify / github / CrunchifyTutorials / target / classes : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / zxing - 2.1.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - logging - 1.1.2.jar
: / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - collections - 3.2.1.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / javax . mail . jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - io - 2.4.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - lang - 2.6.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - configuration - 1.9.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / log4j - 1.2.17.jar : / Users / app / crunchify / github / CrunchifyTutorials / WebContent / WEB - INF / lib / commons - beanutils - 1.8.3.jar
: / Users / app / Library / Application Support / JetBrains / IntelliJIdea2021 . 2 / javascript / extLibs / http_code . jquery . com_jquery - 3.6.0.js : / Users / app / . m2 / repository / org / glassfish / javax . json / 1.1.4 / javax . json - 1.1.4.jar : / Users / app / . m2 / repository / com / github / wnameless / json - flattener / 0.2.2 / json - flattener - 0.2.2.jar : / Users / app / . m2 / repository / com / eclipsesource / minimal - json / minimal - json / 0.9.4 / minimal - json - 0.9.4.jar : / Users / app / . m2 / repository / com / github / wnameless / json / json - flattener / 0.12.0 / json - flattener - 0.12.0.jar
: / Users / app / . m2 / repository / com / fasterxml / jackson / core / jackson - databind / 2.12.0 / jackson - databind - 2.12.0.jar : / Users / app / . m2 / repository / com / fasterxml / jackson / core / jackson - annotations / 2.12.0 / jackson - annotations - 2.12.0.jar : / Users / app / . m2 / repository / com / fasterxml / jackson / core / jackson - core / 2.12.0 / jackson - core - 2.12.0.jar
: / Users / app / . m2 / repository / org / apache / commons / commons - text / 1.9 / commons - text - 1.9.jar : / Users / app / . m2 / repository / com / github / wnameless / json / json - base / 2.0.0 / json - base - 2.0.0.jar : / Users / app / . m2 / repository / commons - io / commons - io / 2.10.0 / commons - io - 2.10.0.jar
: / Users / app / . m2 / repository / com / google / code / gson / gson / 2.8.7 / gson - 2.8.7.jar : / Users / app / . m2 / repository / net / jodah / expiringmap / 0.5.9 / expiringmap - 0.5.9.jar : / Users / app / . m2 / repository / org / apache / httpcomponents / httpclient / 4.5.13 / httpclient - 4.5.13.jar : / Users / app / . m2 / repository / org / apache / httpcomponents / httpcore / 4.4.13 / httpcore - 4.4.13.jar
: / Users / app / . m2 / repository / commons - codec / commons - codec / 1.11 / commons - codec - 1.11.jar : / Users / app / . m2 / repository / org / json / json / 20210307 / json - 20210307.jar : / Users / app / . m2 / repository / net / spy / spymemcached / 2.12.3 / spymemcached - 2.12.3.jar : / Users / app / . m2 / repository / com / whalin / Memcached - Java - Client / 3.0.2 / Memcached - Java - Client - 3.0.2.jar
: / Users / app / . m2 / repository / commons - pool / commons - pool / 1.5.6 / commons - pool - 1.5.6.jar : / Users / app / . m2 / repository / com / googlecode / xmemcached / xmemcached / 2.4.7 / xmemcached - 2.4.7.jar : / Users / app / . m2 / repository / com / paypal / sdk / rest - api - sdk / 1.14.0 / rest - api - sdk - 1.14.0.jar
: / Users / app / . m2 / repository / org / apache / commons / commons - dbcp2 / 2.8.0 / commons - dbcp2 - 2.8.0.jar : / Users / app / . m2 / repository / org / apache / commons / commons - pool2 / 2.8.1 / commons - pool2 - 2.8.1.jar : / Users / app / . m2 / repository / commons - dbcp / commons - dbcp / 20030825.184428 / commons - dbcp - 20030825.184428.jar : / Users / app / . m2 / repository / javax / ws / rs / javax . ws . rs - api / 2.1.1 / javax . ws . rs - api - 2.1.1.jar : / Users / app / . m2 / repository / org / hamcrest / hamcrest - all / 1.3 / hamcrest - all - 1.3.jar : / Users / app / . m2 / repository / org / apache / logging / log4j / log4j - core / 2.14.1 / log4j - core - 2.14.1.jar : / Users / app / . m2 / repository / org / apache / logging / log4j / log4j - api / 2.14.1 / log4j - api - 2.14.1.jar
: / Users / app / . m2 / repository / com / google / guava / guava / 30.1.1 - jre / guava - 30.1.1 - jre . jar : / Users / app / . m2 / repository / com / google / guava / failureaccess / 1.0.1 / failureaccess - 1.0.1.jar : / Users / app / . m2 / repository / com / google / guava / listenablefuture / 9999.0 - empty - to - avoid - conflict - with - guava / listenablefuture - 9999.0 - empty - to - avoid - conflict - with - guava . jar : / Users / app / . m2 / repository / com / google / code / findbugs / jsr305 / 3.0.2 / jsr305 - 3.0.2.jar
: / Users / app / . m2 / repository / org / checkerframework / checker - qual / 3.8.0 / checker - qual - 3.8.0.jar : / Users / app / . m2 / repository / com / google / errorprone / error_prone_annotations / 2.5.1 / error_prone_annotations - 2.5.1.jar : / Users / app / . m2 / repository / com / google / j2objc / j2objc - annotations / 1.3 / j2objc - annotations - 1.3.jar : / Users / app / . m2 / repository / com / googlecode / json - simple / json - simple / 1.1.1 / json - simple - 1.1.1.jar : / Users / app / . m2 / repository / junit / junit / 4.10 / junit - 4.10.jar : / Users / app / . m2 / repository / org / hamcrest / hamcrest - core / 1.1 / hamcrest - core - 1.1.jar : / Users / app / . m2 / repository / commons - net / commons - net / 3.8.0 / commons - net - 3.8.0.jar : / Users / app / . m2 / repository / org / ow2 / asm / asm / 9.1 / asm - 9.1.jar : / Users / app / . m2 / repository / axis / axis / 1.4 / axis - 1.4.jar : / Users / app / . m2 / repository / org / apache / axis / axis - jaxrpc / 1.4 / axis - jaxrpc - 1.4.jar : / Users / app / . m2 / repository / axis / axis - wsdl4j / 1.5.1 / axis - wsdl4j - 1.5.1.jar : / Users / app / . m2 / repository / commons - beanutils / commons - beanutils / 1.9.4 / commons - beanutils - 1.9.4.jar : / Users / app / . m2 / repository / commons - collections / commons - collections / 3.2.2 / commons - collections - 3.2.2.jar : / Users / app / . m2 / repository / org / apache / commons / commons - collections4 / 4.4 / commons - collections4 - 4.4.jar : / Users / app / . m2 / repository / org / apache / commons / commons - configuration2 / 2.7 / commons - configuration2 - 2.7.jar
: / Users / app / . m2 / repository / commons - discovery / commons - discovery / 0.5 / commons - discovery - 0.5.jar : / Users / app / . m2 / repository / org / apache / commons / commons - lang3 / 3.12.0 / commons - lang3 - 3.12.0.jar : / Users / app / . m2 / repository / commons - logging / commons - logging / 1.2 / commons - logging - 1.2.jar : / Users / app / . m2 / repository / commons - logging / commons - logging - api / 1.1 / commons - logging - api - 1.1.jar : / Users / app / . m2 / repository / javax / mail / javax . mail - api / 1.6.2 / javax . mail - api - 1.6.2.jar : / Users / app / . m2 / repository / javax / mail / mail / 1.4.7 / mail - 1.4.7.jar : / Users / app / . m2 / repository / javax / activation / activation / 1.1 / activation - 1.1.jar : / Users / app / . m2 / repository / javax / xml / jaxrpc - api / 1.1 / jaxrpc - api - 1.1.jar : / Users / app / . m2 / repository / org / apache / axis / axis - saaj / 1.4 / axis - saaj - 1.4.jar : / Users / app / . m2 / repository / wsdl4j / wsdl4j / 1.6.3 / wsdl4j - 1.6.3.jar : / Users / app / . m2 / repository / com / google / zxing / core / 3.4.1 / core - 3.4.1.jar : / Users / app / . m2 / repository / org / apache / commons / commons - compress / 1.20 / commons - compress - 1.20.jar : / Users / app / . m2 / repository / mysql / mysql - connector - java / 8.0.25 / mysql - connector - java - 8.0.25.jar : / Users / app / . m2 / repository / com / google / protobuf / protobuf - java / 3.11.4 / protobuf - java - 3.11.4.jar
: / Users / app / . m2 / repository / ch / qos / logback / logback - classic / 1.3.0 - alpha5 / logback - classic - 1.3.0 - alpha5 . jar : / Users / app / . m2 / repository / ch / qos / logback / logback - core / 1.3.0 - alpha5 / logback - core - 1.3.0 - alpha5 . jar : / Users / app / . m2 / repository / com / sun / mail / javax . mail / 1.6.2 / javax . mail - 1.6.2.jar : / Users / app / . m2 / repository / edu / washington / cs / types / checker / checker - framework / 1.7.0 / checker - framework - 1.7.0.jar : / Users / app / . m2 / repository / commons - validator / commons - validator / 1.7 / commons - validator - 1.7.jar : / Users / app / . m2 / repository / commons - digester / commons - digester / 2.1 / commons - digester - 2.1.jar : / Users / app / . m2 / repository / org / springframework / spring - context / 5.3.8 / spring - context - 5.3.8.jar : / Users / app / . m2 / repository / org / springframework / spring - aop / 5.3.8 / spring - aop - 5.3.8.jar : / Users / app / . m2 / repository / org / springframework / spring - beans / 5.3.8 / spring - beans - 5.3.8.jar
: / Users / app / . m2 / repository / org / springframework / spring - core / 5.3.8 / spring - core - 5.3.8.jar : / Users / app / . m2 / repository / org / springframework / spring - jcl / 5.3.8 / spring - jcl - 5.3.8.jar : / Users / app / . m2 / repository / org / springframework / spring - expression / 5.3.8 / spring - expression - 5.3.8.jar : / Users / app / . m2 / repository / org / springframework / spring - context - support / 5.3.8 / spring - context - support - 5.3.8.jar : / Users / app / . m2 / repository / org / slf4j / slf4j - api / 1.7.31 / slf4j - api - 1.7.31.jar : / Users / app / . m2 / repository / org / slf4j / jul - to - slf4j / 1.7.31 / jul - to - slf4j - 1.7.31.jar : / Users / app / . m2 / repository / org / slf4j / jcl - over - slf4j / 1.7.31 / jcl - over - slf4j - 1.7.31.jar : / Users / app / . m2 / repository / org / slf4j / log4j - over - slf4j / 1.7.31 / log4j - over - slf4j - 1.7.31.jar crunchify . com . tutorials . CrunchifyFindMaxOccurrence
 
 
Words # of Occurances
com 1
largest 1
clients 1
technical 1
passionate 1
leading 1
for 2
their 1
we 2
into 1
transform 1
premium 1
world 1
are 2
attracting 1
have 1
free 1
crunchify 4
over 1
tech 1
all 1
desire 1
blogging 2
resource 2
in 1
16 1
& 3
is 1
also 1
ideas 1
+ 1
great 1
users 1
the 3
excel 1
help 1
site 1
million 1
trusted 1
beginners 1
monthly 1
online 1
reality 1
to 1
who 1
 
Maximum Occurrence of Word in file :
== > crunchify : 4
 
Process finished with exit code 0

示例 2 文件：

1
this and and and then and this
输出：
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3
4
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7
Words # of Occurances
and 4
this 2
then 1
 
Maixmum Occurance of Word in file :
== > and : 4

您在寻找更多的 Java 教程吗？ 看看这个集合。