问题描述
我已经编写了insertBefore，insertAfter，insertAtHead和insertAtTail函数，我计划将所有这些函数合并到一个insert（）函数中，这些函数将在从文本文件中读取新值时执行插入排序。 / p>
主文件：
/*This program utilizes linked lists to keep track of all words in a text document. It produces a cross-reference,or a concordance.
It keeps track each of the words in a given file,the number of times it occurs,and which line numbers contain the word.*/
import java.util.Scanner;
import java.io.*;
public class Main
{
public static void main(String args[]) throws FileNotFoundException
{
//declare/initialize linkedlist,scanner,input string and file
LinkedList list = new LinkedList();
Scanner scan = new Scanner(system.in);
String line;
String[] lineWords;
File file;
int c = 0;
boolean done = false;
boolean ignore;
do
{
//ask for file name
System.out.println("Please enter the filename: ");
line = scan.next();
file = new File(line);
//check if file exists
if (!file.exists())
{
System.out.println("That file doesn't exist. Please try again.");
continue;
}
//read from file
scan = new Scanner(file);
//loop to display lines from file
while (scan.hasNextLine())
{
line = scan.nextLine();
c += 1;
System.out.println(c + " " + line);
//remove any unnecessary characters
line = helper.format(line);
//split line into array of words
lineWords = line.split(" ");
//insert words into linkedlist
for (int i = 0; i < lineWords.length; i++)
{
//check if word should be ignored
ignore = helper.shouldIgnore(lineWords[i]);
//check if the current string is a word that should be ignored
if (ignore) continue;
//check if line contains characters
else if (line.matches(".*\\w.*")) list.insert(lineWords[i],c);
//otherwise don't add to the list
else continue;
}
}
//close scanner and exit do-while loop
scan.close();
done = true;
} while (!done);
//print blank line
System.out.println("");
//display list
list.display();
}
}
Helper文件（仅格式化字符串并排除单词）
/*This file contains numerous helper functions for functionality*/
public class helper
{
//remove unnecessary characters
static public String format(String s)
{
s = s.replace(",","");
s = s.replace(".","");
s = s.replace(";","");
s = s.replace(":","");
s = s.replace("\"","");
s = s.replace("?","");
s = s.replace("(","");
s = s.replace(")","");
s = s.replace("!","");
s = s.replace("\r\n","").replace("\n","");
s = s.toLowerCase();
return s;
}
//function to ignore a,an,and the
static public boolean shouldIgnore(String s)
{
if (s.equals("the") || s.equals("The") || s.equals("a") || s.equals("A") || s.equals("an") || s.equals("An")) return true;
else return false;
}
}
罪魁祸首，我的LinkedList文件：
/*This file contains the functions and defining classes for linkedlists and nodes.*/
public class LinkedList
{
//declare LinkedList values
int size;
Node head;
Node tail;
private static class Node
{
//node data
String word;
int line;
Node next;
Node prev;
//constructor
public Node(String w,int l)
{
this.word = w;
this.line = l;
this.next = null;
}
}
//inserts node at head of list
public void insert(String s,int l)
{
//create node to traverse through list
Node current = head;
//assign arguments to new node
Node n = new Node(s,l);
//check if list is empty
if (head == null)
{
this.insertAtHead(n);
}
while (current != null)
{
if (current.word.compareto(n.word) > 0)
{
System.out.println("YOOOO");
this.insertBefore(current,n);
}
else
{
System.out.println("noooo");
System.out.println(current.word + " --> " + n.word);
this.display();
this.insertAfter(current,n);
}
current = current.next;
}
}
//insert a node before a specified node
public void insertBefore(Node a,Node n)
{
//make the prevIoUs of the new node the prevIoUs of the specified node
n.prev = a.prev;
//make the prevIoUs of the specified node the new node
a.prev = n;
//make the next of the new node the specified node
n.next = a;
//if the new node has a prevIoUs node,make the next of the prevIoUs node the new node
if(n.prev != null) n.prev.next = n;
}
//insert a node after a specified node
public void insertAfter(Node a,Node n)
{
//check if the prevIoUs node is null
if (a == null)
{
System.out.println("Error. You can't insert after a null node.");
return;
}
//make next of new node the next of prevIoUs node
n.next = a.next;
//make next of prevIoUs node the new node
a.next = n;
//make the prevIoUs of the new node the prevIoUs node
n.prev = a;
//make the prevIoUs of the new node's next node the new node
if (n.next != null) n.next.prev = n;
}
//insert node at head of list
public void insertAtHead(Node n)
{
//Assign the head to be the node after the new node
n.next = head;
//make the prevIoUs value of the new node null
n.prev = null;
//make the prevIoUs node of the head the new node
if (head != null) head.prev = n;
//make the head point to the new node
head = n;
}
//insert node at tail of list
public void insertAtTail(Node n)
{
//make a node to use to iterate through the list
Node last = head;
//the next of the tail must be null
n.next = null;
//check if the list is empty
if (head == null)
{
n.prev = null;
head = n;
return;
}
//else iterate through the list
while (last.next != null) last = last.next;
//make the next node of the current tail the
last.next = n;
/* 7. Make last node as prevIoUs of new node */
n.prev = last;
}
//displays list
public void display() {
//start at head
Node n = head;
//check if list is empty
if(head == null)
{
System.out.println("List is empty");
return;
}
//traverse through list
while(n != null)
{
System.out.println(n.word);
n = n.next;
}
}
}
解决方法
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