Using Struts2 Tags to Formatting Numbers

Question

I want to format some numbers in our jsp pages.
first i define some resources in my porperties
format.number.with2Decimal={0,number,#0.00}

......
Question1:
i want to know what is the ‘#’ and '0' means?
0.00,#0.00,##.00,###0.00
who can tell me the differences between them? thanks!

Question2:
if i define a BigDecimal type in my action BigDecimal number1;

Then my page should using a format to show this value,
1.if number1=null then show -NIL-
2.if number1=0 then show -NIL-
3.if number1>0 then show 1.00,3434.98 .....
please ignore number<0

Question3:
change number1 to a String,
1.if number1=null or empty or blank then show -NIL-
2.if number1=Hello then show Hello ....

could you give me help?

Answer 1

Question1: i want to know what is the ‘#’ and '0' means? 0.00,#0.00,##.00,###0.00 who can tell me the differences between them? thanks!

• 0 means that a number must be printed, no matter if it exists
• # means that a number must be printed if it exists, omitted otherwise.

Example:

    System.out.println("Assuming US Locale: " + 
                             "',' as thousand separator, " + 
                             "'.' as decimal separator   ");

    NumberFormat nf = new DecimalFormat("#,##0.0##");
    System.out.println("\n==============================");
    System.out.println("With Format (#,##0.0##) ");
    System.out.println("------------------------------");
    System.out.println("1234.0 = " + nf.format(1234.0));
    System.out.println("123.4  = " + nf.format(123.4));
    System.out.println("12.34  = " + nf.format(12.34));
    System.out.println("1.234  = " + nf.format(1.234));
    System.out.println("==============================");

    nf = new DecimalFormat("#,000.000");
    System.out.println("\n==============================");
    System.out.println("With Format (#,000.000) ");
    System.out.println("------------------------------");
    System.out.println("1234.0 = " + nf.format(1234.0));
    System.out.println("123.4  = " + nf.format(123.4));
    System.out.println("12.34  = " + nf.format(12.34));
    System.out.println("1.234  = " + nf.format(1.234));
    System.out.println("==============================");

Running Example

Output:

Assuming US Locale: ',' as thousand separator, '.' as decimal separator)

==============================
With Format (#,##0.0##) 
------------------------------
1234.0 = 1,234.0
123.4  = 123.4
12.34  = 12.34
1.234  = 1.234
==============================

==============================
With Format (#,000.000) 
------------------------------
1234.0 = 1,234.000
123.4  = 123.400
12.34  = 012.340
1.234  = 001.234
==============================

In Struts2, you can apply this kind of format with the getText() function from ActionSupport.

P.S: Question 2 and 3 are trivial (and messy).