Java accessing specific element in array of strings

Question

I am running a web crawler for my own use. I downloaded one and want to provide it with seeds. I want to provide it with around 50 seeds. So I created an array of strings. I want to provide the crawler with 1 seed each time it goes through my for loop. My code is :

String[ ] temp = new String[ ] {"http://www.random.org/","http://www.wikipedia.org/", "http://www.jlworld.com/","http://www.frys.com/"};

String[ ] urls = new String[temp.length];
  for (int i = 0; i <=temp.length; i++)       
     {          
        urls[i] = temp[i];      
     }

The crawler needs a string assigned to urls. So like :

String[ ] urls = new String[1];

urls[0] = "http://www.google.com/";

So it works like that. I get an outofbounds exception though for my code. What I want to do is provide the crawler with 1 of the seeds each time it goes through the for loop. Any help on this would be appreciated!

As a side note, instead of using the loop yourself, look into System.arraycopy (download.oracle.com/javase/1.4.2/docs/api/java/lang/…) — corsiKa
– corsiKa, Commented Feb 21, 2011 at 19:21

Erik · Accepted Answer · 2011-02-21 18:43:09Z

5

for (int i = 0; i <=temp.length; i++)

Should be:

for (int i = 0; i <temp.length; i++)

answered Feb 21, 2011 at 18:43

Erik

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Comments

Dave McClelland · Accepted Answer · 2011-02-21 18:53:42Z

2

for(int i = 0; i < temp.length; i++)

Calling .length on an array returns the size of the array, but array indices are 0-based. For your loop, you were correct in starting with i = 0, but you only want to go to i = (temp.length - 1) or you will get an index out of bounds exception. Comparing i < temp.length instead of i <= temp.length accounts for this shift in index basing.

edited Feb 21, 2011 at 18:53

answered Feb 21, 2011 at 18:42

Dave McClelland

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1 Comment

Jesper Over a year ago

There's no such thing as an "1-based size". The size is the size. If there are 10 elements in the array then the size is 10. Simple.

George · Accepted Answer · 2011-02-21 18:44:28Z

1

Change the line

for (int i = 0; i <=temp.length; i++)

to

for (int i = 0; i < temp.length; i++)

You were looping one too many times

answered Feb 21, 2011 at 18:44

George

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Comments

Daniel · Accepted Answer · 2011-02-21 18:43:14Z

0

for (int i = 0; i < temp.length; i++) {          
    String url = temp[i];      

    ... handle url...
}

answered Feb 21, 2011 at 18:43

Daniel

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Comments

duffymo · Accepted Answer · 2011-02-21 18:43:29Z

0

Why not have a Map of [URL, seed] pairs instead of raw arrays? Do the lookup using the URL and off you go.

answered Feb 21, 2011 at 18:43

duffymo

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Comments

Vivek Goel · Accepted Answer · 2011-02-21 18:43:50Z

0

Code should be

 for (int i = 0; i <temp.length; i++)       
 {          
    urls[i] = temp[i];      
 }

Array index start from 0 to length-1

answered Feb 21, 2011 at 18:43

Vivek Goel

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