How to use String.format() in Java to replicate tab “\t”?

问题

I'm printing data line by line and want it to be organized like a table.

I initially used firstName + ", " + lastName + "\t" + phoneNumber.

But for some of the larger names, the phone number gets pushed out of alignment

I'm trying to use String.format() to achieve this effect. Can anyone tell me the format syntax to use?

I tried String.format("%s, %s, %20s", firstName, lastName, phoneNumber), but that's not what I want. I want it to look like this:

John, Smith 123456789

Bob, Madison 123456789

Charles, Richards 123456789

Edit: These answers seem to work for System.out.println(). But I need it to work for a JTextArea. I'm using textArea.setText()

Worked it out. JTextArea doesn't use monospaced fonts by default. I used setFont() to change that, and now it works like a charm. Thank you all for the solutions.

回答1:

consider using a negative number for your length specifier: %-20s. For example:

   public static void main(String[] args) {
     String[] firstNames = {"Pete", "Jon", "Fred"};
     String[] lastNames = {"Klein", "Jones", "Flinstone"};
     String phoneNumber = "555-123-4567";

      for (int i = 0; i < firstNames.length; i++) {
        String foo = String.format("%-20s %s", lastNames[i] + ", " + 
             firstNames[i], phoneNumber);
        System.out.println(foo);
      }   
   }

returns

Klein, Pete          555-123-4567
Jones, Jon           555-123-4567
Flinstone, Fred      555-123-4567

回答2:

Try putting the width into second placeholder with - sign for right padding as:

  String.format("%s, %-20s %s", firstName, lastName, phoneNumber)

This will give the specified width to the second argument(last name) with right padding and phone number will start after the specified width string only.

EDIT: Demo:

String firstName = "John";
String lastName = "Smith";
String phoneNumber = "1234456677";
System.out.println(String.format("%s, %-20s %s",firstName, lastName, phoneNumber));

prints:

John, Smith 1234456677

回答3:

The only alternative is loop the names list, calculate the maximum length of the String, and add whitespaces as needed after every name to ensure that all the numbers begin at the same column.

Using tabs has the disavantage that you cannot know a priori how many whitespace are equivalent to a tab, since it is dependent of the editor.

来源：https://stackoverflow.com/questions/13789141/how-to-use-string-format-in-java-to-replicate-tab-t

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java

syntax

tabs

format