String.format and arrays

Question

Is there a way to conveniently use String.format (or printf) to print the values in an array. Example:

public static void main(String[] args) {
    System.out.printf("Today is %tc and your args are %TAG", new Date(), args);
}

The output I'm looking for:

Today is Sat Oct 14 14:54:51 CEST 2017 and your args are uno dos tres

As the example suggests, I don't know how long the args array is? So far the only solution I've come up with is to first use .format to do get the first part of the string, then loop through the args array and append space separated chunks.

M. le Rutte · Accepted Answer · 2017-10-14 13:17:45Z

3

You have Arrays.toString(...), which will format it as ["unos", "dos", tres"], but I assume that is not what you want.

Usually I use the streaming api to collect the result into a string: Arrays.stream(args).collect(Collectors.joining(" "));

public static void main(String[] args) {
  System.out.printf("Today is %tc and your args are %s%n", new Date(), 
    Arrays.stream(args).collect(Collectors.joining(" ")));
}

edited Oct 14, 2017 at 13:17

answered Oct 14, 2017 at 13:02

M. le Rutte

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1 Comment

M. le Rutte Over a year ago

To clarify the edit undo: The %n in prinf means "use the platform specific code for going to a new line".

Andy Turner · Accepted Answer · 2017-10-14 13:13:18Z

0

Since it is not a primitive array, you can wrap args in a list:

System.out.printf("%Tc %s", new Date(), Arrays.asList(args));

This then uses the implementation of toString for List.

answered Oct 14, 2017 at 13:13

Andy Turner

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