我对 java 很陌生，并且正在从事一个基本项目，正在尝试使用 txt 文件。在这种情况下，我有一个名为“活动”的 txt 文件，其中包含一组活动，每个活动都与一个 ID 相关联。然后用户可以通过以下代码决定是否查看、添加或修改活动：
import java.io.*;
import java.util.*;
public class ActivitiesModification {
private static Scanner x;
public static void main(String[] args) throws IOException {
String acfilepath = "C:\\Users\\John\\Desktop\\Activities.txt";
File actxt = new File(acfilepath); //Name of the File Storing the activities (currently on desktop)
FileWriter fw = new FileWriter(actxt, true); //FileWriter object representing the Activities txt file
PrintWriter pw = new PrintWriter(fw); //PrintWriter object representing the Activities txt file
Scanner sc = new Scanner(actxt); //Scanner object which will scan through the txt file
Scanner scinput = new Scanner(System.in); //Scanner object which scans user input
System.out.println("What would you like to do? (view/add/modify)");
String action = scinput.nextLine(); //User input responsible for switch statement (Pre-UI temporary)
switch(action) {
case("view"):{
System.out.println("The currently available activities are as follows:");
viewActivities(actxt);
break;
}
case("add"):{
System.out.println("Please add the desired activity name");
String addac = scinput.nextLine();
int counter = 1;
while(sc.hasNextLine()){
sc.nextLine();
counter++;
}
pw.println(counter + " " + addac);
break;
}
case("modify"):{
System.out.println("Please enter the ID of the activity whose name you would like to modify");
String editTerm = scinput.nextLine();
System.out.println("Please enter the new activity name");
String newActivity = scinput.nextLine();
editActivities(acfilepath, editTerm, newActivity);
System.out.println("The activity name has been changed as requested. Would you like to view the full list of available activities?");
String ds = scinput.nextLine();
if(ds.equalsIgnoreCase("yes")) {
viewActivities(actxt);
}
}
}
pw.close();
scinput.close();
sc.close();
}
public static void editActivities(String filepath, String editTerm, String newActivity) {
String tempFile = "C:\\Users\\John\\Desktop\\temp.txt";
File oldFile = new File(filepath);
File newFile = new File(tempFile);
String ID = ""; String activity = "";
try {
FileWriter fw1 = new FileWriter(tempFile, true);
BufferedWriter bw1 = new BufferedWriter(fw1);
PrintWriter pw1 = new PrintWriter(bw1);
x = new Scanner(new File(filepath));
while(x.hasNext()) {
ID = x.next();
activity = x.next();
if(ID.equals(editTerm)) {
pw1.println(ID + " " + newActivity);
}
else {
pw1.println(ID + " " + activity);
}
}
x.close();
pw1.flush();
pw1.close();
bw1.close();
fw1.close();
oldFile.delete();
File dump = new File(filepath);
newFile.renameTo(dump);
}
catch(Exception e) {
}
}
public static void viewActivities(File filepath) throws FileNotFoundException { // "filepath" will be the name of the file object which the scanner will scan through (actxt)
Scanner sc = new Scanner(filepath);
while(sc.hasNextLine()) {
System.out.println(sc.nextLine());
}
sc.close();
}
}
但是，由于某种原因，代码的“修改”部分将无法正常运行。而不是创建一个新的临时文件，删除旧的并重命名临时文件活动。它只是创建一个临时文件，传输适当的内容并且不删除/重命名。
我最初在另一个项目上运行了上述代码（使用相同的文件），它运行良好。将代码传输到此项目中的方法时，它停止工作，我不知道为什么。