我正在练习java,这对我来说是新的,最近学习了java中的集合。我想解析 csv 文件并将其存储在 HashMap 上。另外,我不想使用任何解析器。
我的CSV文件:-
id,date,ministry,questions
2011,15.02.2014,HEALTH,What was the outcome
20757,24.02.2015,"DEFENCE , FINANCE" ,"Your budget this year .."
20113,17.03.2013,HEALTH, Hospitals build
所以,我有几个问题:-
- 我希望在同一列中包含
“DEFENCE , FINANCE”
。我将如何使用正则表达式删除“,”,以便分隔符不会设置新列 - 我想显示每个部委提出的问题数量。这里例如:-健康总共有 2 个问题等。
- 也没有重复项。
我正在通过 I/O 文件读取器进行解析。
我的代码:-
public class MainData {
public static void main(String[] args) throws IOException ,FileNotFoundException{
String line = "";
String cvsSplitBy = ",";
try{
BufferedReader br = new BufferedReader(new FileReader("src/main/resources/rj.csv"));
HashMap<String,String> rjFile = new HashMap<String, String>();
System.out.println("running"+rjFile);
while ((line = br.readLine()) != null) {
String[] rj = line.split(cvsSplitBy);
System.out.println(br);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
PS:- 我只想使用与 map 相关的集合。
最佳答案
这是一个帮助您入门的简单示例。我已经采用了两种方法(问题列表和问题计数)。选择适合您需要的一个并删除另一个或同时使用两者:
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class MainData {
public static void main(String[] args) throws IOException, FileNotFoundException {
String line = "";
String cvsSplitBy = ",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)";
try {
BufferedReader br = new BufferedReader(new FileReader("src/main/resources/rj.csv"));
Map<String, List<String>> questListByMinistry = new HashMap<>();
Map<String, Integer> questCountByMinistry = new HashMap<>();
//skip the first line (header)
br.readLine();
while ((line = br.readLine()) != null) {
String[] rj = line.split(cvsSplitBy);
if(!questCountByMinistry.containsKey(rj[2])){
//if the ministry doesn't exist as key yet put it to your map and put the value 1
questCountByMinistry.put(rj[2], 1);
}
else{
//else if it already exist get the current value and add +1
questCountByMinistry.put( rj[2], questCountByMinistry.get(rj[2])+1);
}
//-----------------------------------------------
if(!questListByMinistry.containsKey(rj[2])){
//if key doesen't exist put it to map and create a new list
questListByMinistry.put(rj[2], new ArrayList<>());
// and add the question to the list
questListByMinistry.get(rj[2]).add(rj[3]);
}
else{
//else if key already exists get the list associated to key and add the question
questListByMinistry.get(rj[2]).add(rj[3]);
}
}
System.out.println(questCountByMinistry);
System.out.println(questListByMinistry);
} catch (IOException e) {
e.printStackTrace();
}
}
}
如果您使用的是Java8或以上版本/如果您想熟悉Java8的功能
上面的代码可以重写为:
public static void main(String[] args) throws IOException, FileNotFoundException {
String line = "";
String cvsSplitBy = ",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)";
try {
BufferedReader br = new BufferedReader(new FileReader("src/main/resources/rj.csv"));
Map<String, List<String>> questListByMinistry = new HashMap<>();
Map<String, Integer> questCountByMinistry = new HashMap<>();
//skip the first line
br.readLine();
while ((line = br.readLine()) != null) {
String[] rj = line.split(cvsSplitBy);
questListByMinistry.computeIfAbsent(rj[2], k -> new ArrayList<>()).add(rj[3]);
questCountByMinistry.compute(rj[2], (k,v) -> v==null? 1 : v+1);
}
System.out.println(questCountByMinistry);
System.out.println(questListByMinistry);
} catch (IOException e) {
e.printStackTrace();
}
}
关于java - 解析csv文件并在java集合hashmap中显示特定信息,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58539298/