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我是一名新手 java 程序员，我的 java 项目的文件输出有问题。在这个项目中，我应该有一个“Rock, Paper, Scissors”程序，它将结果输出到一个单独的文件中。当我运行程序然后查看文件时，它只记录最近的结果而不是每个结果。任何关于做什么的建议都会很棒。请原谅糟糕的表格；我稍后会清理它。我还删除了大部分评论以缩短它。谢谢。

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


public class RockPaperScissors {


    public static int count = 0;

    public static void main(String[] args) {

            execute(); 
    }


    public static void execute(){       

        System.out.println("This program will allow you to play \n\"Rock, Paper, Scissors\" against a computer.");
        System.out.println();
        System.out.println("Enter 'r' for Rock, 'p' for Paper, or s for Scissors.");
        System.out.println("Enter 'w' to have an insta-win for that round. Enter '-1' at anytime to exit program.");

        String info = userInput();
        int value = guessCode();
        decideOutcome(value, info);
        again();
        }


        public static String userInput() {
        Scanner console = new Scanner (System.in);  
        String s = console.next();
        return s;
    }

        public static int guessCode() {
        Random r = new Random ();   
        return (r.nextInt(3)+1); // Random integer between 1 and 3;
    }

    public static void decideOutcome(int i, String j) {

        try {
            PrintStream output = new PrintStream(new File ("records.txt"));

            if (j.equalsIgnoreCase("rock")|| j.equalsIgnoreCase("r")) {
                count++;
                switch (i){
                    case 1:
                        System.out.println("You've won! Computer picked scissors.");
                        output.println(count + " Win ");
                        break;
                    case 2:
                        System.out.println("You've tied.... Computer also picked rock.");
                        output.println(count + " Tie ");
                        break;
                    case 3:
                        System.out.println("You've lost. Computer picked paper.");
                        output.println(count + " Loss ");
                        break;
                    }           
            } else if (j.equalsIgnoreCase("paper")|| j.equalsIgnoreCase("p")) {
                count++;
                switch (i){
                    case 1:
                        System.out.println("You've lost; Computer picked scissors.");
                        output.println(count + " Loss ");
                        break;
                    case 2:
                        System.out.println("You've won! Computer picked rock.");
                        output.println(count + " Win ");
                        break;
                    case 3:
                        System.out.println("You've tied.... Computer also picked paper.");
                        output.println(count + " Tie ");
                        break;
                    }
            } else if (j.equalsIgnoreCase("scissors")|| j.equalsIgnoreCase("s")) {
                count++;
                switch (i){
                    case 1:
                        System.out.println("You've tied.... Computer picked scissors.");
                        output.println(count + " Tie ");
                        break;
                    case 2:
                        System.out.println("You've lost; Computer picked rock.");
                        output.println(count + " Loss ");
                        break;
                    case 3:
                        System.out.println("You've won! Computer also picked paper.");
                        output.println(count + " Win ");
                        break;
                    }
            } else if (j.equalsIgnoreCase("w")) {
                count++;
                System.out.println("You've effortlessly defeated the computer!");
                output.println(count + " Win ");
            } else if (j.equals("-1")) {
                System.out.println("Thanks for playing!"); // need to find way to reach end.

                if (count == 1) { // If the user terminates after the first match.
                    System.out.println("You've played a single match.");        
                } else if (count > 1) { // Anything more than 1 match played upon termination.
                    System.out.println("You've played " + count + " matches total.");   
                } else { // This is for exceptions when user inputs gibberish for their sign and then 'no' for the second input.
                    System.out.println("No matches were played.");  
            }           
                System.out.println("Good Bye!");
                System.exit(0);
            } else {
                System.out.println("You didn't input the right thing.");
            }
        } catch (FileNotFoundException e) {
                System.out.println("File was not found; try again");
        }
    }

    public static void again() {
            System.out.println("Do you want to play again? (Type in 'y' for Yes or 'n' for No.)");

            Scanner console2 = new Scanner (System.in);

            String t = console2.next();

            while (t.equalsIgnoreCase("yes")||t.equalsIgnoreCase("y")) {
                System.out.println();
                System.out.println();
                execute(); // 
            }  
            if (t.equalsIgnoreCase("no") || t.equalsIgnoreCase("n") || t.equals("-1")) {
                System.out.println("Hope you had fun! I'm sure I've had just as much fun with making this program! Good Bye!");         

                if (count == 1) { // If the user terminates after the first match.
                        System.out.println("You've played a single match.");        
                } else if (count > 1) { // Anything more than 1 match played upon termination.
                        System.out.println("You've played " + count + " matches total.");   
                } else { // This is for exceptions when user inputs gibberish for their sign and then 'no' for the second input.
                        System.out.println("No matches were played.");              
                }   
                System.exit(0);

            } else { // If the user doesn't input 'yes' or 'no.'
                System.out.println("Not the proper response, but it's assumed that you don't want to continue.");   
                if (count == 1) { // If the user terminates after the first match.
                    System.out.println("You've completed a single match."); 
                } else if (count >= 2) { // Anything more than 1 match played upon termination.
                    System.out.println("You've completed " + count + " matches total.");
                } else { // The user haphazardly messes up both inputs.
                    System.out.println("No matches were finished.");
                }
                System.exit(0);
            }
        }
}
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3 回答 3

2

当您 时decideOutcome()，您PrintStream每次都重新打开文件。

但是这个构造函数并没有寻找到文件的末尾！这意味着您每次都会覆盖内容。

尝试使用 aFileWriter来代替，并使用适当的构造函数。

编辑：由于作业似乎要求您使用PrintStream（为什么？），您将不得不这样做：

PrintStream output = new PrintStream(new FileOutputStream("records.txt", true));

但在现实生活中，您可能会使用 aBufferedWriter来代替；几乎没有人使用PrintStream.

于 2013-05-26T05:48:02.097 回答
1

您正在使用的 Printstream 从头开始​​写入文件，而不是从最后一行开始写入。使用 Filewriter 处理文件会更好，因为它具有附加和插入模式。您需要的是附加模式。

于 2013-05-26T06:19:55.333 回答
1

您永远不能使用 aPrintStream以您正在执行的方式完成此任务。API 明确指出 的构造函数PrintStream执行以下操作：

PrintStream(File file) 使用指定的文件创建一个新的打印流，不自动刷新行。

file - 用作此打印流目标的文件。如果文件存在，那么它将被截断为零大小；否则，将创建一个新文件。输出将被写入文件并被缓冲。

没有允许您附加到前一个文件的构造函数。

因此，解决方案在于您只能使用PrintStream构造函数一次。这可以通过使您的output变量成为类变量并摆脱您的声明（以及try-catch）来实现decideOutcome()。

private static PrintStream output;

public static void main(String[] args) {
  try {
    output = new PrintStream(new File("records.txt"));
    execute();
  } catch (FileNotFoundException e) {
    System.out.println("File was not found; try again");
  } finally {
    output.close();
  }
}

另一个需要注意的重要事项是，无论何时打开诸如 Scanner 或 PrintStream 之类的流时，都应始终关闭它。关闭它们的最佳位置是在一个finally子句中，因为您的代码的那部分保证可以运行。

于 2013-05-26T06:28:08.237 回答