java - 如何以右对齐方式打印数字？

Question

所以我正在尝试一次代码评估的简单问题 multiplication tables

其中一个要求是

(The numbers are right-aligned and strip out leading/trailing spaces on each line)

我不知道如何做到这一点，我当前的代码看起来像

private static void printTable(final int numberOfTables, final int numberOfTimes) {
        for (int i = 1; i <= NUMBER_OF_TABLES; i++) {
            final StringBuilder sb = new StringBuilder();
            for (int j = 1; j <= NUMBER_OF_TIMES; j++) {
                sb.append(i * j).append("    ");
            }
            System.out.println(sb.substring(0, sb.length() - 4));
        }
    }

我得到的是

1    2    3    4    5    6    7    8    9    10    11    12
2    4    6    8    10    12    14    16    18    20    22    24
3    6    9    12    15    18    21    24    27    30    33    36
4    8    12    16    20    24    28    32    36    40    44    48
5    10    15    20    25    30    35    40    45    50    55    60
6    12    18    24    30    36    42    48    54    60    66    72
7    14    21    28    35    42    49    56    63    70    77    84
8    16    24    32    40    48    56    64    72    80    88    96
9    18    27    36    45    54    63    72    81    90    99    108
10    20    30    40    50    60    70    80    90    100    110    120
11    22    33    44    55    66    77    88    99    110    121    132
12    24    36    48    60    72    84    96    108    120    132    144

如何右对齐数字？

Answer 1

正如您在问题标题中所说，您使用printf()。比如，

for (int i = 1; i <= NUMBER_OF_TABLES; i++) {
    for (int j = 1; j <= NUMBER_OF_TIMES; j++) {
        System.out.printf("%6d", i * j);
    }
    System.out.println();
}

其中 6 是宽度，Javadoc 为 Formatter将宽度描述为

Width

The width is the minimum number of characters to be written to the output. For the line separator conversion, width is not applicable; if it is provided, an exception will be thrown.

还有

'd' ... Formats the argument as a decimal integer.