align columns of strings and explain '\t' (java)

dave bean · 01-10-2004, 07:35 AM

hi
I have an array of objects. Each object contains 4 string variables and a method to display these variables. The method looks like this

Code:

System.out.println(string1 + "\t" + string2 + "\t" + string3 + "\t" + string4);

i call the method with a for loop in another class, for all the objects in the array call this method. As a result i have many lines of text written to the console but they are not aligned propely and i want them in straight columns.

My questions are:
1. 'why is is that the '\t' does not create an equal space between each string, sometimes its 2 chars, sometimes its 5 or 6?

2. Even if the tab made a consistently sized space my columns would not be aligned propely as not all the strings are the same length. Is there a built in method which would say . .

-write first string
-write second string on same line but 10 chars from the left
-write third string on same line but 20 chars from left

im trying to make a method of my own but its a lot of code so really im looking for an economical shortcut.

thanks

deiussum · 01-10-2004, 07:41 PM

A tab generally will advance the cursor to the next tab space. A common tab spacing is 8, so if you were to do something like so...

Code:

System.out.println("012345678901234567890");
System.out.println("a\tb");
System.out.println("abc\tdef");
System.out.println("abcdefghijklm\tnop");

You get a result similar to the following if the tab columns are every 8th place..

Code:

012345678901234567890
a       b
abc     def
abcdefghijklm   nop

Note that a single tab will add white space up to the next tab column. (In this case the tab alignment is every 8 characters.)

So... if you want to make sure everything is alligned by using tabs, you'll have to know at what tab space each column is at, and how long each column you print out is, so that you know how many tabs you need to use in order to align the next column on the appropriate tab.

So for example, if you wanted to align the above, you'd need to use this instead.

Code:

System.out.println("012345678901234567890");
System.out.println("a\t\tb");
System.out.println("abc\t\tdef");
System.out.println("abcdefghijklm\tnop");


Results:
012345678901234567890
a               b
abc             def
abcdefghijklm   nop

dave bean · 01-10-2004, 09:17 PM

ok thanks deiussum

so would you say the fastest way to do this is to check the number of characters in the column before printing out, and then set the number of tabs accordingly for each line ?

deiussum · 01-10-2004, 10:55 PM

That is one option. If you were using C/C++, I would say that using a library such as ncurses might give you a bit more control of formatting where you want to write everything w/o using tabs. I don't know of any libraries offhand that will do that for Java, but I'm guessing they probably exist somewhere.