Printing with t tabs does not result in aligned columns

Question

I have a very weird problem  After writing this   for  File f   currentFile listFiles                      if   f isDirectory             System out println f getName     t   Dir t  Command getpremission f    t  f getTotalSpace               else          System out println f getName     t   File t  Command getpremission f    t  f getTotalSpace             I see this printed   see txt File    rw  267642728448 see1 txt    File    rw  267642728456 see2 txt    File    rw  267642728448   Why is there a problem with the tabs

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Building on this question  I use the following code to indent my messages   String prefix1    short text    String prefix2    looooooooooooooong text    String msg    indented        The second string begins after 40 characters  The dash means that the   first string is left-justified     String format     -40s s n   System out printf format  prefix1  msg   System out printf format  prefix2  msg     This is the output    short text                              indented looooooooooooooong text                 indented   This is documented in section  Flag characters  in man 3 printf

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The problem is the length of the filenames   The first filename is only 7 chars long  so the tab occurs at char 8  doing a tab after every 4 characters    However the next filenames are 8 chars long  so the next tab won t be until char 12   And if you had filenames longer than 11 chars  you d run into the same problem again

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As mentioned by other folks  the variable length of the string is the issue   Rather than reinventing the wheel  Apache Commons has a nice  clean solution for this in StringUtils   StringUtils rightPad  String to extend  100     100 is the length you want to pad out to

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You can also pad a string to the required length using Guava s Strings padEnd String input  int minLength  char padding

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The length of the text that you are providing in each line is different  this is the problem  so if the second word is too long  see2 txt is long 8 char which corresponds to a single tab lenght  it prints out a tab which goes to the next tabulation point  One way to solve it is to programmatically add a pad to the f getName   text so each text generated  see txt or see2 txt has the same lenght  for example see txt  and see2 txt  so each tab automatically goes to the same tabulation point   If you are developing with JDK 1 5 you can solve this using java util Formatter   String format     -20s  5d n   System out format format   test   1   System out format format   test2   20   System out format format   test3   5000     this example will give you this print   test                     1 test2                   20 test3                 5000

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In continuation of the comments by P  ter and duncan  I normally use a quick padding method  something like -   public String rpad String inStr  int finalLength        return  inStr                                   typically a sufficient length spaces string            substring 0  finalLength       similarly you can have a lpad   as well

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The  problem  with the tabs is that they indent the text to fixed tab positions  typically multiples of 4 or 8 characters  depending on the console or editor displaying them   Your first filename is 7 chars  so the next tab stop after its end is at position 8  Your subsequent filenames however are 8 chars long  so the next tab stop is at position 12   If you want to ensure that columns get nicely indented at the same position  you need to take into account the actual length of previous columns  and either modify the number of following tabs  or pad with the required number of spaces instead  The latter can be achieved using e g  System out printf with an appropriate format specification  e g    1 13s  specifies a minimum width of 13 characters for displaying the first argument as a string

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You can use this example to handle your problem   System out printf    -15s  15s  n    name    lastname    System out printf    -15s  15s  n    Bill    Smith      You can play with the     until you find the right alignment to satisfy your needs

[java] Printing with "\t" (tabs) does not result in aligned columns

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