无法将输入写入文件

Question

I have tried many times to read a user input and then write it to a file but I haven't find a solution. Here is my code...

The main class.

import java.util.HashMap;
import java.util.Scanner;

public class cShell{
    static String Currentpath="C:\\";
    public String Current = Currentpath;
    static HashMap<String, ICommand> myhashData=new HashMap<String, ICommand>();

    public static void main(String[] args)
    {
        myhashData.put("ltf", new cITF());
        myhashData.put("nbc", new cNBC());
        myhashData.put("gdb", new cGDB());
        myhashData.put("Tedit", new cTedit());

        String Input = "";
        do{
            System.out.print(Currentpath+"> ");
            //String Input = "";
            Scanner scan = new Scanner(System.in);
            if(scan.hasNext()){
                Input = scan.nextLine().trim();             
            }

            if(Input.equals("exit")){
                System.exit(0);
            }

            if(myhashData.containsKey(Input)){
                ICommand myCommand=myhashData.get(Input);
                myCommand.Execute();
            }
            else{
                System.out.println("Invalid Command");
            }

        }while(!Input.equals("exit"));
    }
}

This is the class that do the read and write.

import java.util.*;
import java.io.*;
import java.nio.file.Files;
import java.nio.file.Path;
//import java.lang.System.*;

public class cTedit implements ICommand{

    @Override
    public void Execute() {         
        String filename = "";
        System.out.println("Enter the file name to be edited");
        Scanner scan = new Scanner(System.in);
        if(scan.hasNext()){
            filename = scan.nextLine();
        }

        String line = null;
        try{
            InputStreamReader ISR = new InputStreamReader(System.in);
            //FileReader fileReader = new FileReader(ISR);
            FileWriter fileWriter = new FileWriter(cShell.Currentpath+"\\"+filename);
            BufferedReader bufferedReader = new BufferedReader(ISR);
            System.out.println("Enter text into the file");
            while((line = bufferedReader.readLine()) != null){
                 fileWriter.write(line);
            }
        bufferedReader.close();
        }catch(FileNotFoundException ex){
            System.out.println("Unable to open file '" + filename + "'");
        }
        catch(IOException ex){
            System.out.println("Error reading file '" + filename + "'");
        }
    }
}

My problem is when I enter some text as user input, pressing enter doesn't stop me from entering inputs, but when I press Ctrl+z it ran into an infinite loop.

Answer 1

Try this one in cTedit class.

bufferedReader.readLine() will never return null in your case.

Type exit to come out of loop.

    while((line = bufferedReader.readLine()) != null){
         if(line.equals("exit")){
           break;
         }
         fileWriter.write(line);
     }

Use fileWriter.close() in the end.

Answer 2

Maybe that's not the source of your problem, but I don't think that you need to check the hasnext() condition to read a line :

if(scan.hasNext()){
     filename = scan.nextLine();
}

just filename = scan.nextLine(); should be enough.

Answer 3

Use the following

 if(Input.equals("exit") || Input.equals("")){
                System.exit(0);
 }

instead of

 if(Input.equals("exit")){
                System.exit(0);
}

In order to close the fileWriter after just before exiting add a method closeFile as below.

import java.util. ; import java.io. ; import java.nio.file.Files; import java.nio.file.Path; //import java.lang.System.*;

public class cTedit implements ICommand{ private FileWriter fileWriter; @Override public void Execute() { // TODO Auto-generated method stub

String filename = "";
System.out.println("Enter the file name to be edited");
Scanner scan = new Scanner(System.in);
if(scan.hasNext()){
    filename = scan.nextLine();
}

String line = null;

try{

    InputStreamReader ISR = new InputStreamReader(System.in);
    //FileReader fileReader = new FileReader(ISR);
    fileWriter = new FileWriter(cShell.Currentpath+"\\"+filename);

      BufferedReader bufferedReader = new BufferedReader(ISR);
    System.out.println("Enter text into the file");
    while((line = bufferedReader.readLine()) != null){
         fileWriter.write(line);
     }
     bufferedReader.close();
}catch(FileNotFoundException ex){
    System.out.println("Unable to open file '" + filename + "'");
}
catch(IOException ex){
    System.out.println("Error reading file '" + filename + "'");
} finally {
    fileWriter.close();
}

}

 public void closeFile() {
     fileWriter.close();
 }

}

and then callCloseFile in cShell class just before exiting