PrintWriter＆File in java

Question

我寫了一個程序，允許用戶在一個文件中存儲多個備忘錄。我想出瞭如何在Java中使用PrintWriter &文件，但是我的問題與我的輸出有關。當我在記事本中檢查文件時，我只能輸入一個備忘錄，沒有問題&，只有一個備忘錄存在。下面的代碼：

import java.util.*; 
import java.io.*; 

public class MemoPadCreator{ 

    public static void main(String[] args) throws FileNotFoundException { 

    Scanner input = new Scanner(System.in); 
    boolean lab25 = false; 
    File file = new File("revisedLab25.txt"); 
    PrintWriter pw = new PrintWriter (file); 
    String answer = ""; 

    do{ 
     while(!lab25){ 

     System.out.print("Enter the topic: "); 
     String topic = input.nextLine(); 

     Date date = new Date(); 
     String todayDate = date.toString(); 

     System.out.print("Message: "); 
     String memo = input.nextLine(); 

     pw.println(todayDate + "\n" + topic + "\n" + memo); 
     pw.close(); 

     System.out.print("Do you want to continue(Y/N)?: "); 
     answer = input.next(); 
     } 

    }while(answer.equals("Y") || answer.equals("y")); 

    if(answer.equals("N") || answer.equals("n")){ 
     System.exit(0); 
    } 

    } 
} 

下面是輸出：

Enter the topic: I love food! 
Message: Food is life! 
Do you want to continue(Y/N)?: Y 
Enter the topic: Message: 

如何去改變它，以便輸出可以讓我繼續儲存的備忘錄，直到我告訴它停下來？

Answer 1

try { 
    Files.write(Paths.get("revisedLab25.txt"), ("the text"todayDate + "\n" + topic + "\n" + memo).getBytes(), StandardOpenOption.APPEND); 
}catch (IOException e) { 
    //exception handling 
} 

因爲你具有潛在的多次寫入爲用戶增加了輸入循環，你可以用一個Try-with-resources try塊寫操作。試用資源需要在離開試塊時關閉文件：

try(PrintWriter pw= new PrintWriter(new BufferedWriter(new FileWriter("revisedLab25.txt", true)))) { 

    do{ 
     while(!lab25){ 

     System.out.print("Enter the topic: "); 
     String topic = input.nextLine(); 

     Date date = new Date(); 
     String todayDate = date.toString(); 

     System.out.print("Message: "); 
     String memo = input.nextLine(); 

     pw.println(todayDate + "\n" + topic + "\n" + memo); 

     System.out.print("Do you want to continue(Y/N)?: "); 
     answer = input.next(); 
     } 

    }while(answer.equals("Y") || answer.equals("y")); 
} 
catch (IOException e) { 
    //exception handling 
}