如何在Java中用下划线填充数字？

Question

如何用Java中的下划线填充数字,而不是通常的零？

比如我想要的

• 123.45将被编入___ 123.45和
• 12345.67格式为_12345.67
• 0.12格式为_ __ _ __ .12

我尝试了很多东西,最接近的是我(通过使用SYMBOLS.setZeroDigit('_');):

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;

public class Example {

    public static void main(String[] args) {
        DecimalFormatSymbols SYMBOLS = new DecimalFormatSymbols();
        SYMBOLS.setDecimalSeparator('.');
        SYMBOLS.setGroupingSeparator(',');
        DecimalFormat OUTPUT_FORMAT = new DecimalFormat("000,000.00", SYMBOLS);

        System.out.println(OUTPUT_FORMAT.format(0.01));
        // got 000,000.01
        System.out.println(OUTPUT_FORMAT.format(0.12));
        // got 000,000.12
        System.out.println(OUTPUT_FORMAT.format(123456));
        // got 123,456.00
        System.out.println(OUTPUT_FORMAT.format(123456.78));
        // got 123,456.78
        System.out.println(OUTPUT_FORMAT.format(1234));
        // got 001,234.00
        System.out.println(OUTPUT_FORMAT.format(1234.56));
        // got 001,234.56

        SYMBOLS.setZeroDigit('_');
        OUTPUT_FORMAT = new DecimalFormat("000,000.00", SYMBOLS);
        System.out.println(OUTPUT_FORMAT.format(0.01));
        // expected ______._1 but got ___,___._`
        System.out.println(OUTPUT_FORMAT.format(0.12));
        // expected ______.12 but got ___,___.`a
        System.out.println(OUTPUT_FORMAT.format(123456));
        // expected 123,456.__ but got `ab,cde.__
        System.out.println(OUTPUT_FORMAT.format(123456.78));
        // expected 123,456.78 but got `ab,cde.fg
        System.out.println(OUTPUT_FORMAT.format(1234));
        // expected __1,234.00 or at least __1,234.__ but got __`,abc.__
        System.out.println(OUTPUT_FORMAT.format(1234.56));
        // expected __1,234.56 but got __`,abc.de
    }

}

好吧,如果形成正确(带尾随下划线),不是非常接近但是空数字: _ __,_ __.__

无论如何,关于如何获得预期行为的建议？

Answer 1

"_________".substring( num.length() )+num;

这里num是String牵着你的号码.要将a转换double为a String,您可以使用Double.toString(myDouble).