[英]Associating values with keys in a HashMap from text file [Java]
I have a text file that has a printer followed by a print job associated with that printer: 我有一个文本文件,其中包含一个打印机,后跟与该打印机关联的打印作业:
LaserJet This assignment involves . . .
LaserJet Budget for November . . .
Lexmark Invoice Number 334222: . . .
Samsung Class schedule for 2013/01/06 . . .
Lexmark Production schedule . . .
Samsung Class schedule for 2013/02/06 . . .
LaserJet Memo to Bobby Hill . . .
Lexmark Meeting in 20 minutes . . .
Lexmark Conference call transcript . . .
Lexmark Production schedule is off time . . .
Lexmark Last Production schedule . . .
LaserJet Print a crapload of pages . . .
I want to read the text file into my program and create a HashMap with the printer name as the key and associate the printjob with its corresponding printer. 我想将文本文件读入我的程序并创建一个以打印机名称为键的HashMap,并将printjob与其相应的打印机相关联。 so i will end up with something like:
所以我最终会得到类似的东西:
LaserJet
This assignment involves . . .
udget for November . . .
Memo to Bobby Hill . . .
Print a crapload of pages . . .
Samsung
Class schedule for 2013/01/06 . . .
Class schedule for 2013/02/06 . . .
Lexmark
Invoice Number 334222: . . .
etc. ( the file could contain 1000's of jobs with many different printers ). 等(该文件可能包含1000个具有许多不同打印机的作业)。 I am struggling with associating a printjob with its printer though.
我正在努力将printjob与其打印机相关联。 this is my code so far:
到目前为止这是我的代码:
import java.util.*;
public class Printers {
private String sPrinterName;
private String sContent;
private Map<String, ArrayList<String>> mapOfJobs = new HashMap<String, ArrayList<String>>();
private ArrayList<String> collectionContent = new ArrayList<String>();
private ArrayList<String> collectionPrinters = new ArrayList<String>();
public Printers() { }
public void loadCollections( Scanner input ) {
while ( input.hasNext() ) {
sPrinterName = input.next(); // get printer name
sContent = input.nextLine(); // get string ( print job )
if ( !collectionPrinters.contains(sPrinterName))
collectionPrinters.add(sPrinterName);
collectionContent.add(this.sContent);
}
}
public void buildMap() { // the process of creating the HashMap
for ( int i = 0; i < collectionPrinters.size(); i++ ) {
String refToPrinter = collectionPrinters.get(i);
String refToContent = collectionContent.get(i);
if ( !mapOfJobs.containsKey( refToPrinter ) ) {
ArrayList<String> tmp = new ArrayList<String>();
tmp.add( refToContent );
mapOfJobs.put( refToPrinter, tmp );
}
else if ( !mapOfJobs.get( refToPrinter ).contains( refToContent ) )
mapOfJobs.get( refToPrinter ).add( refToContent );
}
}
public void displayAll() { // print everything
Iterator iterator = mapOfJobs.keySet().iterator();
while (iterator.hasNext()) {
String key = iterator.next().toString();
String value = mapOfJobs.get(key).toString();
System.out.println(key + " " + value);
}
}
public String toString() {
return String.format("Printer: %s Job: %s", sPrinterName, sContent );
}
}
i have another class with main that creates a Printers object to call the methods. 我有另一个使用main的类,它创建一个Printers对象来调用方法。 Anyway the code only outputs:
无论如何代码只输出:
LaserJet [ This assignment involves . . .]
Lexmark [ Budget for November . . .]
Samsung [ Invoice Number 334222: . . .]
help is appreciated.. 帮助表示赞赏..
If I have understood properly, your issue is you want to read the jobs from a file and send that to a printer for printings. 如果我已正确理解,您的问题是您想要从文件中读取作业并将其发送到打印机进行打印。
Till now you are done with the Map creation and you are facing issue with the print job. 到目前为止,您已完成地图创建,并且您将面临打印作业的问题。
Please let me know if I have missed any point here. 如果我错过了任何一点,请告诉我。
I think while populating the HashMap you can use Map> so that you can maintain a queue for each printer. 我认为在填充HashMap时,您可以使用Map>,这样您就可以为每台打印机维护一个队列。 If you want the content of a printer to be unique ie same content can not be printed twice you can use Map>.
如果您希望打印机的内容是唯一的,即相同的内容无法打印两次,您可以使用Map>。
Not sure if it helps you. 不确定它是否对你有所帮助。 Let me know if you have any specific questions.
如果您有任何具体问题,请与我们联系。
You don't need so many Collections
, only mapOfJobs
HashMap is enough, 你不需要那么多
Collections
,只有mapOfJobs
HashMap就足够了,
public void loadResult( Scanner input ) {
while ( input.hasNextLine() ) {
String line=input.nextLine();
sPrinterName = line.subString(0, line.indexOf(' '));// printer name
sContent = line.subString(line.indexOf(' ')+1); // get string ( print job )
List<String> contentList=mapOfJobs.get(sPrinterName);
if(contentList==null ){
contentList=new ArrayList<>();
}
contentList.add(sContent);
mapOfJobs.put(sPrinterName,contentList)
}
}
After your call to loadCollections
the collections will have different number of rows. 在调用
loadCollections
,集合将具有不同的行数。 If the example text was the complete file you would have 3 rows in collectionPrinters and 12 rows in collectionContent. 如果示例文本是完整文件,则collectionPrinters中将包含3行,collectionContent中将包含12行。 And you have removed the association between printers and content.
并且您已删除了打印机和内容之间的关联。
You just need to build your map, in pseudo code: 您只需要使用伪代码构建地图:
for each line
if no map entry
create map entry with content
else
append content to map entry
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