如何解决如何将字符串数组扫描和处理为另一个没有重复的多维数组？
| 抱歉，标题有点混乱。我需要做的是读取一个文本文件，其中包含许多城市和州，它们位于不同的行，如下所示：Salem,Oregon
St. George,Utah
Augusta,Maine
Portland,Maine
Jefferson City,Missouri
Kansas City,Missouri
Portland,Oregon
Salt Lake City,Utah
Maine: Augusta,Portland
Missouri: Jefferson City,Kansas City
Oregon: Portland,Salem
Utah: Salt Lake City,St. George
import java.io.File;
import java.util.Scanner;
import java.util.Formatter;
import java.io.FileNotFoundException;
import java.util.Arrays;
public class munge
{
private String inFileName,outFileName;
private Scanner inFile;
private Formatter outFile;
private int line = 0;
private String[] data;
public munge(String inFileName,String outFileName)
{
this.inFileName = inFileName;
this.outFileName = outFileName;
data = new String[100];
}
public void openFiles()
{
try
{
inFile = new Scanner(new File(inFileName));
}
catch(FileNotFoundException exception)
{
System.err.println(\"File not found.\");
System.exit(1);
}
catch(SecurityException exception)
{
System.err.println(\"You do not have access to this file.\");
System.exit(1);
}
try
{
outFile = new Formatter(outFileName);
}
catch(FileNotFoundException exception)
{
System.err.println(\"File not found.\");
System.exit(1);
}
catch(SecurityException exception)
{
System.err.println(\"You do not have access to this file.\");
System.exit(1);
}
}
public void readRecords()
{
while(inFile.hasNext())
{
data[line] = inFile.nextLine();
System.out.println(data[line]);
line++;
}
}
public void writeRecords()
{
for(int i = 0; i < line; i++)
{
String tokens[] = data[i].split(\",\");
Arrays.sort(tokens);
for(int j = 0; j < tokens.length; j++)
outFile.format(\"%s\\r\\n\",tokens[j]);
}
}
public void closeFiles()
{
if(inFile != null)
inFile.close();
if(outFile != null)
outFile.close();
}
}
解决方法
这是一些带有注释的代码，希望对您有所帮助：
// your input file with city,state values
File file = new File(\"states.txt\");
// data structure to hold mapping of state to list of cities,sorted by state
SortedMap<String,List<String>> map = new TreeMap<String,List<String>>();
// scan file by line and populate data structure
Scanner scanner = new Scanner(file).useDelimiter(\"\\\\n\");
while (scanner.hasNext()) {
String line = scanner.next();
// only process lines with a comma
if (line.contains(\",\")) {
// split the line on the comma and extract the city and state
// note this won\'t work properly if the city has a comma in it
String[] parts = line.split(\",\");
String city = parts[0].trim();
String state = parts[1].trim();
// if the state doesn\'t exist in the map yet,create it
List<String> cities = map.get(state);
if (cities == null) {
cities = new ArrayList<String>();
map.put(state,cities);
}
// add the city to the list for the state if it\'s not in it yet
if (!cities.contains(city)) {
cities.add(city);
}
}
}
// iterate over the states for output
for (String state : map.keySet()) {
// build up a string for each state with the list of cities
StringBuilder sb = new StringBuilder();
// start with the state
sb.append(state + \": \");
// now append the cities
List<String> cities = map.get(state);
for (String city : cities) {
sb.append(city + \",\");
}
// remove the last comma
sb.delete(sb.length() - 2,sb.length());
// print out the finished line
String output = sb.toString();
System.out.println(output);
}
Map<String,List<String>>
/*
Store each State as a key in the HashMap.
For each State assign an arraylist of cities.
We use StringTokenizer to split the state and the city.
*/
HashMap<String,ArrayList<String>> hmStateCity = new HashMap<String,ArrayList<String>>();
public void readRecords()
{
while(inFile.hasNext())
{
String sInputLine = inFile.nextLine();
StringTokenizer stInput = new StringTokenizer(sInputLine,\",true);
int i = 0; //when i is 0 = State,1 = city
ArrayList<String> arrCity = new ArrayList<String>();
while (stInput.hasMoreElements())
{
String sToken = stInput.nextElement();
if( i == 0)
{
arrCity = hmStateCity.get( sToken );
if(arrCity == null)
{ // this indicates that this particular State was never created.
// so assign a new ArrayList to the State.
arrCity = new ArrayList<String>();
hmStateCity.put( token,arrCity );
}
}
else if( i == 1 )
{
arrCity.add( sToken );
}
i++;
}
}
}
/* Iterate through HashMAp. The Map\'s key is the State name.
Retrieve the List of cities using the \"State\".
The String sStateCityLine will have each line that can be written one at a time.
*/
public void writeRecords()
{
if(hmStateCity !=null)
{
Set<String> setStateName = hmStateCity.keySet();
for(String sState : setStateName )
{
String sStateCityLine = sState + \":\" ;
ArrayList<String> arrCity = hmStateCity.get( sState );
if( arrCity!=null && !arrCity.isEmpty() )
{
boolean isFirstCity = true;
for(String sCity : arrCity )
{
if( !isFirstCity )
{
sStateCityLine = sStateCityLine + \",\";
}
sStateCityLine = sStateCityLine + \" \" + sCity;
isFirstCity = false;
}
}
//Insert code here to write the String sStateCityLine line by line
}
}
}
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 dio@foxmail.com 举报，一经查实，本站将立刻删除。
