如何格式化Java控制台输出？自制PC应用收据排版优化

我开发了一款支持自定义组装PC的简易控制台应用，最终会打印包含所选配件的收据，但目前输出的收据排版不规整。以下是现有代码及期望的规整排版样式，请问如何实现该格式化效果？

现有代码 #

public static void printReceipt() {
        System.out.println("=================================");
        System.out.println("          Your Receipt           ");
        System.out.println("=================================");

        System.out.println("1) " + mbName + "             " + mbPrice);
        System.out.println("2) " + proName + "             " + proPrice);
        System.out.println("8) " + gpuName + "             " + gpuPrice);
        System.out.println("3) " + ramName + "             " + ramPrice);
        System.out.println("4) " + stoName + "             " + stoPrice);
        System.out.println("5) " + coolName + "             " + coolPrice);
        System.out.println("6) " + psuName + "             " + psuPrice);
        System.out.println("7) " + cabName + "             " + cabPrice);

        double total = subtotal(mbPrice, proPrice, ramPrice, stoPrice, coolPrice, psuPrice, cabPrice, gpuPrice);

        System.out.println("=================================");
        System.out.println("GRAND TOTAL:       " + total + "/-");
        System.out.println("=================================");

        System.out.println(" =================================");
        System.out.println("|            Thank you            |");
        System.out.println(" =================================");

    }

期望排版样式 #

=================================
          Your Receipt           
=================================

  Item                   Price
 ------                 -------

1) Asus                  20000.0
2) INTEL                 45000.0
8) Nvidia gtx 1050ti     17000.0
3) Asus                  18000.0
4) Samsung               20000.0
5) Coolermaster          20000.0
6) Ortis                  4000.0
7) Asus                   4000.0
=================================
GRAND TOTAL:            148000.0/- 
================================= 

解决方案 #

核心是使用Java的System.out.printf()方法，通过格式化占位符控制文本的对齐方式和宽度，实现规整排版：

1. 表头与分隔线：保留原有顶部分隔线和标题，新增Item和Price表头，用格式化保证两者对齐。
2. 配件行格式化：用"%2d) %-20s %10.1f%n"这类占位符：
   • %2d：序号占2个字符宽度，右对齐（确保1)、8)这类序号对齐）
   • %-20s：配件名占20个字符宽度，左对齐（短名称自动补空格，长名称超出会自动换行，可按需调整宽度）
   • %10.1f：价格占10个字符宽度，右对齐，保留1位小数（可调整小数位数）
3. 总计行格式化：同样用占位符固定GRAND TOTAL:的宽度，让总价对齐到右侧。

修改后的完整代码 #

public static void printReceipt() {
        System.out.println("=================================");
        System.out.println("          Your Receipt           ");
        System.out.println("=================================");
        // 打印表头
        System.out.printf("%n  %-20s %10s%n", "Item", "Price");
        System.out.printf("  %-20s %10s%n", "------", "-------");
        System.out.println();

        // 格式化打印各配件
        System.out.printf("%2d) %-20s %10.1f%n", 1, mbName, mbPrice);
        System.out.printf("%2d) %-20s %10.1f%n", 2, proName, proPrice);
        System.out.printf("%2d) %-20s %10.1f%n", 8, gpuName, gpuPrice);
        System.out.printf("%2d) %-20s %10.1f%n", 3, ramName, ramPrice);
        System.out.printf("%2d) %-20s %10.1f%n", 4, stoName, stoPrice);
        System.out.printf("%2d) %-20s %10.1f%n", 5, coolName, coolPrice);
        System.out.printf("%2d) %-20s %10.1f%n", 6, psuName, psuPrice);
        System.out.printf("%2d) %-20s %10.1f%n", 7, cabName, cabPrice);

        double total = subtotal(mbPrice, proPrice, ramPrice, stoPrice, coolPrice, psuPrice, cabPrice, gpuPrice);

        System.out.println("=================================");
        // 格式化打印总计
        System.out.printf("%-20s %10.1f/-%n", "GRAND TOTAL:", total);
        System.out.println("=================================");

        System.out.println(" =================================");
        System.out.println("|            Thank you            |");
        System.out.println(" =================================");
    }

说明：

• 可根据实际需求调整占位符宽度（比如把%-20s改成%-25s让名称显示更长）
• 如果价格不需要小数，可把%10.1f改成%10.0f（适配double类型）或%10d（适配int类型）

内容的提问来源于stack exchange，提问作者AnuragK