我是一个新手java程序员，我有麻烦的文件输出与我的java项目。在这个项目中，我应该有一个"石头，布，剪刀"程序，将输出结果到一个单独的文件。当我运行程序然后查看文件时，它只记录最近的结果，而不是所有的结果。如果有什么建议就太好了。请原谅我的失礼;我稍后会打扫的。我也删除了大部分的评论，以便缩短它。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);
}
}
}
当您执行decideOutcome()时，每次都要重新打开一个PrintStream文件。
但是这个构造函数并不查找到文件的末尾!这意味着您每次都要覆盖内容。
尝试使用FileWriter代替，使用适当的构造函数。
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BufferedWriter;几乎没有人使用PrintStream。
您正在使用的Printstream从开头开始写入文件，而不是从最后一行开始。使用Filewriter处理文件会更好，因为它有附加和插入模式。您需要的是追加模式。
您永远不能使用PrintStream以您正在做的方式完成此任务。API明确指出PrintStream的构造函数执行以下操作:
PrintStream(文件文件)使用指定的文件创建新的打印流，但不自动刷新行。
file -要用作打印流目的地的文件。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。
没有允许你追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一次PrintStream构造函数。这可以通过使output变量成为一个类变量并去掉decideOutcome()中的声明(以及try-catch)来实现。
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();
}
}
另一件需要注意的重要事情是，无论何时打开一个流(如Scanner或PrintStream)，都应该关闭它。关闭它们的最佳位置是在finally子句中，因为这部分代码可以保证运行。