What ways can you create a string with 2000 "spaces"

Question

For various reasons I am trying to set a string to 2000 spaces. Currently I am using:

String s = String.format("%1$-2000s"," ");

This is great for Java 5, however, some of the developers in our department are using 1.4 and this does not work.

I was wondering, are any other ways of achieving the same result? I know I can do things like a for loop adding a space at a time, but I am looking for something simple like the format option.

For those that may be interested in why I need this, it is because we have an XML type on a dataobject that on insert into the DB is null. It then gets updated with the XML string, usually around 2000 characters in size. In Oracle pre-reserving this space can prevent row migration, therefore, increasing performance.

Thanks!

Insert a single space into a char(2000) field in a database, then select it back out. — aehiilrs, Jul 13 '10 at 20:44
Which Oracle version and are you using XMLTYPE, if so what is the storage clause for the XMLTYPE? — oluies, Jul 13 '10 at 21:03
This is an unconventional solution to a conventional problem. Rather than filling the field with a dummy value, the preferred way to handle this is to set PCTFREE for the table to a level that allows for the expected growth of each row. — Allan, Jul 13 '10 at 21:06
We had to move away from XMLTYPE to support the old form of replication that we were doing. We will use XMLTYPE if we move to a product that supports it. We do use PCTFREE but we never anticipated the rows to be this large. So going forward we are good, but not for the 50 million rows that are currently causing issues. — northpole, Jul 13 '10 at 21:09
re: why you need this - Please please please be sure to document this in the project documentation, the code, and the DB documentation. Your reasoning is sound, but without a good explanation such shenanigans are a bad code smell. — Freiheit, Jul 13 '10 at 21:13
@Freiheit - I completely agree and have taken the steps to document this in detail. — northpole, Jul 13 '10 at 21:14

score 18 · Accepted Answer · edited Jul 08 '12 at 12:39

18

char[] spacesArray = new char[2000];
Arrays.fill(spacesArray, ' ');
String spaces = new String(spacesArray);

edited Jul 08 '12 at 12:39

answered Jul 13 '10 at 20:48

unbeli

29,501
5
55
57

score 3 · Answer 2 · answered Jul 13 '10 at 23:25

the simplest answer: (scroll to see all the codes)

String s = "                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        "; // 2000 spaces

+1 I like this solution. If we know at compile time what the string is, why not hard code it. (However, probably another solution involving the database itself is better.) I tweaked the solution to make it just a little better and to answer Pascal's question. Run it with assertions enabled. String s = ... 2000 spaces ... ; assert s.length()==2000 : "constant string is wrong length." ; — emory, Jul 14 '10 at 02:05

Allan · Answer 3 · 2010-07-13T21:28:21.987

2

You can use lpad(' ',2000,' ') in the insert statement directly to tell Oracle to create the value you want.

In fact, you can set the field in question to have this as the default, which could prevent you from needing to change it in multiple places (if your code is explicitly sending null as the value for the field, that will override the default).

edited Jul 13 '10 at 21:28

answered Jul 13 '10 at 21:21

Allan

17,141
4
52
69

score 1 · Answer 4 · answered Jul 13 '10 at 20:42

1

A StringBuffer and then add a space 2000 times in a loop, and toString() afterwards. I don't think there are any "simpler" ways to do it which doesn't end up doing this anyway under the covers.

If you do this a lot, it would make a good library function.

answered Jul 13 '10 at 20:42

Thorbjørn Ravn Andersen

73,784
33
194
347

3

You can use a StringBuilder instead in order to avoid the small synchronization overhead, and you can also initialize the builder with the target size so that no realocation takes place. – Eyal Schneider Jul 13 '10 at 21:01
StringBuilder is not available in Java 1.4 which the original poster asks about. – Thorbjørn Ravn Andersen Jul 13 '10 at 21:08

score 1 · Answer 5 · answered Jul 13 '10 at 20:56

1

A random function I found in my personal library:

public static String whiteSpace2(int l) {
    if (l==0) return "";
    String half=whiteSpace2(l/2);
    if ((l&1)!=0) {
        return half+" "+half;
    } else {
        return half+half;
    }
}

Not claiming it is the fastest possible way to generate whitespace, but it works :-)

answered Jul 13 '10 at 20:56

mikera

105,238
25
256
415

You really shouldn't be building strings with `+` like this. Use a `StringBuilder`. The `O(log N)` step is nice, though. – polygenelubricants Jul 13 '10 at 21:01
Just fixed my recurrence formula: F(N)=F(N/2)+N. Yes, it is linear, my mistake. – Eyal Schneider Jul 13 '10 at 21:11
6

You do realize that there is a special place in hell for developers who use 'l' as a variable name. – Skip Head Jul 13 '10 at 21:11
I believe the amount of toStrings() drown the log n versus n discussion. – Thorbjørn Ravn Andersen Jul 13 '10 at 21:13
1

All - yes this is a "Joke" in that it was a mildly comical way of writing a completely non-performance-critical utility function :-) – mikera Jul 13 '10 at 21:24

score 0 · Answer 6 · answered Jul 13 '10 at 20:54

0

StringUtils.repeat(" ", 2000) (from commons-lang)

However, I'm not sure whether such micro-optimizations should be made with the cost of code that would require a 5 line comment to explain why is this needed. If you do it - be sure to add an extensive comment, otherwise imagine the reaction of those reading your code.

answered Jul 13 '10 at 20:54

Bozho

588,226
146
1,060
1,140

ya, my function is very well documented for that reason – northpole Jul 13 '10 at 20:56
5

@downvoter - could you explain the downvote? You don't like commons-lang, or my note about the comment? – Bozho Jul 13 '10 at 21:08

score 0 · Answer 7 · answered Jul 13 '10 at 20:59

0

If nothing else works:

StringBuilder sb = new StringBuilder();
for(int i = 0; i < 2000; ++i)
   sb.append(" ");
String str = new String(sb);

answered Jul 13 '10 at 20:59

Viktor Sehr

12,825
5
58
90

7

why not just `sb.toString()` – Jul 13 '10 at 21:02

score 0 · Answer 8 · edited May 23 '17 at 12:22

0

See this other question.

Can I multiply strings in Java to repeat sequences?

Both Apache Commons StringUtils and Google Guava libraries have commands to multiply (repeat) strings.

edited May 23 '17 at 12:22

Community

1
1

answered Aug 23 '11 at 02:53

Basil Bourque

303,325
100
852
1,154

What ways can you create a string with 2000 "spaces"

8 Answers8