Formatting in java

Question

Good day.

I need to format a number in java. So far I have this:

DecimalFormat df2 = new DecimalFormat( "#,###,###,##0.00" );
System.out.println(new Double(df2.format(balance)).doubleValue());

But it prints out this

But I need it to be with two digits in fraction part. How do I do it?

why do you reconvert it to a double if you just want to parse and print it? — Origin
– Origin, Commented Nov 12, 2012 at 9:45

ntalbs · Accepted Answer · 2012-11-12 09:41:01Z

2

You don't have to get double value from formatted string. Just use formatted string, which is returned from format() method of DecimalFormat. So your code should be like the following:

DecimalFormat df2 = new DecimalFormat( "#,###,###,##0.00" );
...
System.out.println(df2.format(balance));

Your original code:

System.out.println(new Double(df2.format(balance)).doubleValue());

What you did in your code is: format the double value to string(which is formatted as you specified in the DecimalFormat instance). Then you convert the formatted string to Double instance and get double value from the object, which is double. And then printed it to console. So the formatted string is gone, and the double value is printed as normal.

edited Nov 12, 2012 at 9:41

answered Nov 12, 2012 at 9:32

ntalbs

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Comments

user529543 · Accepted Answer · 2012-11-12 09:31:13Z

1

"But I need it to be with two digits in fraction part. How do I do it?"

DecimalFormat df2 = new DecimalFormat( );
df2.setMinimumFractionDigits(2);
df2.setMaximumFractionDigits(2);

System.out.println(df2.format(balance));

answered Nov 12, 2012 at 9:31

user529543

Comments

jeroen_de_schutter · Accepted Answer · 2012-11-12 09:31:19Z

0

You could also use the setMinimumFractionDigits method of DecimalFormat

df2.setMinimumFractionDigits(2);

answered Nov 12, 2012 at 9:31

jeroen_de_schutter

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user902383 · Accepted Answer · 2012-11-12 09:36:35Z

0

your decimal format is right, but what you are doing before you print this out is new Double(df2.format(balance)) which create new instant of double, which ignores your formatting.

so if you want to display or log your value df2.format(balance) this should be enough

ie:

System.out.println(df2.format(balance));

answered Nov 12, 2012 at 9:36

user902383

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Subhrajyoti Majumder · Accepted Answer · 2012-11-12 09:37:47Z

0

Try this pattern for formatting #,###,###,##.##-

DecimalFormat df2 = new DecimalFormat( "#,###,###,##.##" );
System.out.println(df2.format(balance));

edited Nov 12, 2012 at 9:37

answered Nov 12, 2012 at 9:28

Subhrajyoti Majumder

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Comments

nhahtdh · Accepted Answer · 2012-11-12 09:41:58Z

This should be sufficient:

DecimalFormat df2 = new DecimalFormat("#,##0.00");
System.out.println(df2.format(balance));

The grouping for separator will follow "the interval between the last one and the end of the integer". So there is no benefit from over-specify. Example from the documentation of DecimalFormat:

The grouping separator is commonly used for thousands, but in some countries it separates ten-thousands. The grouping size is a constant number of digits between the grouping characters, such as 3 for 100,000,000 or 4 for 1,0000,0000. If you supply a pattern with multiple grouping characters, the interval between the last one and the end of the integer is the one that is used. So "#,##,###,####" == "######,####" == "##,####,####".

Another thing is that .format() method already output a String, so there is no point in converting it to double. It will cause Exception to be thrown when balance is more than 1000 (the point when separator comes into effect, and Double class cannot parse the String with separator).

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