DecimalFormat Preserves decimal formatting

DecimalFormat Format method
Everyone in format () A decimal is, always on the format of the ' 0 ' and ' # ' some puzzled it.
eg
1:new DecimalFormat ("00.000"). Format (PI)/results: 03.142
2:new DecimalFormat ("##.###"). Format (PI)/results: 3.142
are formatted for PI, but the first result is 03.142, and the second result is 3.142.
What is the reason for that?
0 and # are placeholders, but they work differently in different places. The following is a concrete comparison of them.
Hope to help you.
0:
More than the actual number of digits, the shortage of places to fill up with 0.
New DecimalFormat ("00.00"). Format (3.14)//Result: 03.14
New DecimalFormat ("0.000"). Format (3.14)//Result: 3.140
New DecimalFormat ("00.000"). Format (3.14)//Result: 03.140
Less than the actual number of digits: The whole number of parts do not change, decimal parts, rounding
New DecimalFormat ("0.000"). Format (13.146)//Result: 13.146
New DecimalFormat ("00.00"). Format (13.146)//Result: 13.15
New DecimalFormat ("0.00"). Format (13.146)//Result: 13.15
#：
More than the number of digits in the actual number, unchanged.
New DecimalFormat ("##.##"). Format (3.14)//Result: 3.14
New DecimalFormat ("#.###"). Format (3.14)//Result: 3.14
New DecimalFormat ("##.###"). Format (3.14)//Result: 3.14
Less than the actual number of digits: The whole number of parts do not change, decimal parts, rounding
New DecimalFormat ("#.###"). Format (13.146)//Result: 13.146
New DecimalFormat ("##.##"). Format (13.146)//Result: 13.15
New DecimalFormat ("#.##"). Format (13.146)//Result: 13.15
Some other uses, (add percent semicolon, thousand semicolon, scientific notation, custom positive negative number template)
Can be referenced
http://jff.iteye.com/blog/576737
http://blog.csdn.net/marcoleung/article/details/176514
Above, if there is any irregularity, please point out.