因此，我正在嘗試對到達時間的列進行排序，以便最早到達時間排在第一位。我是java中csv文件的新手，所以掙扎著大時間。我已經設法讀取csv文件并使用數組打印，但不確定如何對特定列進行排序import java.io.File;import java.io.FileNotFoundException;import java.util.ArrayList;import java.util.Arrays;import java.util.List;import java.util.Scanner;public class readCSV { public static void main(String[] args) { String fileName= "csv.csv"; File file= new File(fileName); // this gives you a 2-dimensional array of strings List<List<String>> lines = new ArrayList<>(); Scanner inputStream; try{ inputStream = new Scanner(file); while(inputStream.hasNext()){ String line= inputStream.next(); String[] values = line.split(","); // this adds the currently parsed line to the 2-dimensional string array lines.add(Arrays.asList(values)); //System.out.println(line); System.out.println(values[0] + ' ' + values[1] + ' ' + values[2] + ' ' + values[3] ); } inputStream.close(); }catch (FileNotFoundException e) { e.printStackTrace(); } // the following code lets you iterate through the 2-dimensional array /*int lineNo = 1; for(List<String> line: lines) { int columnNo = 1; for (String value: line) { System.out.println("Line " + lineNo + " Column " + columnNo + ": " + value); columnNo++; } lineNo++; }*/ }}如果有任何其他改進，例如存儲csv，打印等，我很樂意更改它下面是一個輸入示例： processID arrivalTime burstTime priority 1 0 5 1 2 1 7 2 3 0 2 1 4 2 6 2 5 6 10 3 6 5 4 4 7 6 4 7 8 5 4 8 9 6 6 3 10 6 7 2
2 回答
守著一只汪
TA貢獻1872條經驗 獲得超4個贊
我希望下面的這段代碼能幫助你:)我
做什么，我首先為每一行創建一個對象。之后，我將每個對象與我想與之比較的那行的鍵進行比較。這樣，您也可以選擇要比較的“CSV密鑰”。
您可以使用此代碼，但請記住，我在那里放置了2個“TODO”，如果您不考慮它們，這些可能是空指針異常:)
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
*
* @author runef
*/
public class Test {
public static void main(String[] args) {
new Test();
}
private List<CoolObject> coolObjects = new ArrayList<>();
private String[] linesOfCSV = {"A,B,C,D", "1,2,A,A", "2,1,B,B"};
public Test() {
String[] keys = null;
for (String s : linesOfCSV) {
String[] lineValues = s.split(",");
if (keys == null) {
keys = lineValues;
} else {
Map<String, String> aGoodName = new HashMap<>();
for (int i = 0; i < lineValues.length; i++) {
//TODO: Check if keys[i] exists, check if lineValues[i] exists (if not probs something wrong with CSV)
aGoodName.put(keys[i], lineValues[i]);
}
coolObjects.add(new CoolObject(aGoodName));
}
}
Collections.sort(coolObjects, new SortByKey("A"));
System.out.println("SORTED BY KEY 'A'");
for (CoolObject o : coolObjects) {
for (Map.Entry<String, String> entry : o.getACoolMap().entrySet()) {
System.out.print(entry.getKey() + ": " + entry.getValue() + " ");
}
System.out.print("\n");
}
Collections.sort(coolObjects, new SortByKey("B"));
System.out.println("SORTED BY KEY 'B'");
for (CoolObject o : coolObjects) {
for (Map.Entry<String, String> entry : o.getACoolMap().entrySet()) {
System.out.print(entry.getKey() + ": " + entry.getValue() + " ");
}
System.out.print("\n");
}
}
class CoolObject {
private Map<String, String> aCoolMap;
public CoolObject(Map<String, String> aCoolMap) {
this.aCoolMap = aCoolMap;
}
public Map<String, String> getACoolMap() {
return aCoolMap;
}
}
class SortByKey implements Comparator<CoolObject> {
private String keySorter;
public SortByKey(String keySorter) {
this.keySorter = keySorter;
}
public int compare(CoolObject a, CoolObject b) {
//TODO: CHECK IF KEY EXISTS IN BOTH VALUES! ELSE DO SOMETHING ELSE :) PROBS RETURN -1 SO IT COMES LAST!
return a.getACoolMap().get(this.keySorter).hashCode() - b.getACoolMap().get(this.keySorter).hashCode();
}
}
}
拉莫斯之舞
TA貢獻1820條經驗 獲得超10個贊
這將對一列進行排序。您可以修改它以用于多個列。
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
public class Test {
public static void main(String[] args) throws IOException {
ArrayList<String> list = new ArrayList<>();
int lineNumber = 0;
File csvFile = new File("D://new.csv");
BufferedReader br = new BufferedReader(new FileReader(csvFile));
String line = "";
while ((line = br.readLine()) != null) {
String[] arr = line.split(",");
list.add(arr[0]);
lineNumber++;
}
Collections.sort(list);
list.forEach(i -> System.out.println(i));
}
}
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