从data1.csv中删除新行。
我宁愿使用Map的第二个通用String作为字符串列表，所有内容都几乎相同，如下所示
import java.io.BufferedReader;import java.io.FileReader;import java.io.FileWriter;import java.util.linkedList;import java.util.List;import java.util.Map;import java.util.TreeMap;public class Sort { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new FileReader("data1.csv")); Map<String, List<String>> map = new TreeMap<String, List<String>>(); String line = reader.readLine();//read header while ((line = reader.readLine()) != null) { String key = getField(line); List<String> l = map.get(key); if (l == null) { l = new linkedList<String>(); map.put(key, l); } l.add(line); } reader.close(); FileWriter writer = new FileWriter("sorted_numbers.txt"); writer.write("UserID, Module, Markn"); for (List<String> list : map.values()) { for (String val : list) { writer.write(val); writer.write("n"); } } writer.close(); } private static String getField(String line) { return line.split(",")[0];// extract value you want to sort on }}
