Question

鉴于我的代码：

import java.util.Scanner;

public class AccountTest {

    public static void main(String[] args) {
        Account account1 = new Account(50.00);
        Account account2 = new Account(0.00);

        System.out.printf("account1 balance: $%.2f\n", account1.getBalance());
        System.out.printf("account2 balance: $%.2f\n\n", account2.getBalance());

        Scanner input = new Scanner(System.in);

        System.out.print("Enter withdrawal amount for account1: ");

        double withdrawalAmount = input.nextDouble();

        System.out.printf("\nsubtracting %.2f from account1 balance\n",
                withdrawalAmount);

        account1.debit(withdrawalAmount);

        System.out.printf("account1 balance: $%.2f\n", account1.getBalance());
        System.out.printf("account2 balance: $%.2f\n\n", account2.getBalance());

        System.out.print("Enter withdrawal amount for account2: ");
        withdrawalAmount = input.nextDouble();
        System.out.printf("\nsubtracting %.2f from account2 balance\n",
                withdrawalAmount);
        account2.debit(withdrawalAmount);

        System.out.printf("account1 balance: $%.2f\n", account1.getBalance());
        System.out.printf("account2 balance: $%.2f\n", account2.getBalance());
    }
}

如何将我的“System.out.printf”转储到文件中（转储为不删除文件的内容）？或者可能为每个实例创建单独的文件。任何帮助在这里是初学者。感谢。

Answer 1

1）您可以在运行程序时将stdout重定向到文件

java AccountTest >> test.txt

2）你可以在程序开头重新分配stdout

    PrintStream out = new PrintStream(new FileOutputStream("test.txt", true));
    System.setOut(out);

3）您可以使用java.io.PrintWriter而不是System.out

    PrintWriter out = new PrintWriter(new FileWriter("test.txt", true));
    out.printf( "account1 balance: $%.2f\n", account1.getBalance() );

Answer 2

这取决于您运行此程序的方式。如果手头有POSIX shell，只需将其标准输出重定向到文件即可。

以下内容将附加到日志文件中：

$ java -jar myjar.jar >> log

每次都会创建一个新的epoch日期日志文件（$(…)可能是特定于bash的功能，我不确定）：

$ java -jar myjar.jar > log-$(date +%s)

输出控制台到文本文件？ - Java

2 个答案: