Formatting string output in groovy

Question

I'm trying to print out a basic header in Groovy. I need the first line to have the date left-justified, with the name of the institution centered, and page number right-justified. On the second line I need a report description centered with the name of the report right-justified. I couldn't get an example of the output to paste in correctly to this text field so hopefully this description will suffice, it seems pretty standard.

I retrieve the date, institute name, report description and report name from the database. So those fields are variable in size. I thought something like this would work but it does not right-justify or center correctly:

println String.format("%-${maxColumns}s %s %${maxColumns}s", dbDateTime.format('MMMMM d, yyyy'), institution, 'Page: 1')
println String.format("%-${maxColumns}s %s %${maxColumns}s", '', jobTitle, programName)

I set maxColumns to 80, the character limit. Any help is appreciated, I've searched high and low for this! Thanks!

What are you going to use this for? Are you sure this isn't a task for something like jasper or some lib with a pdf (or other formats) output? — Will
– Will, Commented Aug 9, 2013 at 16:45
It will be basic text output, and the file will be emailed daily to certain individuals. We want to keep this simple, no pdfs just text. — tnichol
– tnichol, Commented Aug 9, 2013 at 16:50
If it was just one item per line, you could use the methods center, padLeft, and padRight. You could write some code to concatenate the results of these three functions into a single line. — jep
– jep, Commented Aug 9, 2013 at 17:30
Yeah I was hoping to avoid doing something like that but I might have to. — tnichol
– tnichol, Commented Aug 9, 2013 at 21:12

tim_yates · Accepted Answer · 2013-08-12 09:29:10Z

A quick and dirty solution might be to do something like this:

def header( int maxWidth=80, ...text ) {
    def cols = maxWidth / text.size()
    def idx = 0
    text.inject( '' ) { s, t ->
        idx++
        if( t instanceof String ) {
            s += t.center( (int)cols )
        }
        else {
            switch( t.align ) {
                case 'left'  : s += t.text.padRight( cols, t.pad ?: ' ' ) ; break
                case 'right' : s += t.text.padLeft(  cols, t.pad ?: ' ' ) ; break
                default      : s += t.text.center(   cols, t.pad ?: ' ' )
            }
        }
        if( s.length() < Math.ceil( cols * idx ) && s.length() < maxWidth ) s += ' '
        s
    }
}

You can then pass it a list of Maps like:

def text = header( [ text:dbDateTime.format( 'MMMMM d, yyyy' ), align:'left' ],
                   [ text:'woo', pad:'-' ],
                   [ text:'Page 1', align:'right' ] )

And printing this will give you:

August 12, 2013            -----------woo------------                     Page 1

Obviously this doesn't handle situations where maxWidth isn't big enough to hold all fields, and probably a few other cases, but it might be a good start?

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