indexOf in a string array

Question

Is there anyway to get indexOf like you would get in a string.

output.add("1 2 3 4 5 6 7 8 9 10);  
String bigger[] = output.get(i).split(" ");
int biggerWher = bigger.indexOf("10");

I wrote this code but its returning an error and not compiling! Any advice ?

possible duplicate of [Where is Java's Array indexOf?](http://stackoverflow.com/questions/4962361/where-is-javas-array-indexof) — Stephen C, Jun 06 '11 at 09:20

score 62 · Accepted Answer · answered Jun 06 '11 at 09:28

62

Use this ...

output.add("1 2 3 4 5 6 7 8 9 10");  
String bigger[] = output.get(i).split(" ");
int biggerWher = Arrays.asList(bigger).indexOf("3");

answered Jun 06 '11 at 09:28

Saurabh Gokhale

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What are the collateral effects by using asList? Is made a copy of original array on memory? – richardaum Jun 13 '14 at 17:27
@Richard: It will create a new ArrayList object and converts from the String array, I'd guess 3-5 times the amount of memory than before. public static List asList(T... array) { return new ArrayList(array); } – John Dec 18 '14 at 03:38

Stephen C · Answer 2 · 2011-06-06T09:24:35.727

13

When the array is an array of objects, then:

Object[] array = ..
Arrays.asList(array).indexOf(someObj);

Another alternative is org.apache.commons.lang.ArrayUtils.indexOf(...) which also has overloads for arrays of primitive types, as well as a 3 argument version that takes a starting offset. (The Apache version should be more efficient because they don't entail creating a temporary List instance.)

edited Jun 06 '11 at 09:24

answered Jun 06 '11 at 09:18

Stephen C

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Why do I keep forgetting that most collection-methods apply to arrays too by using `asList`.... +1 – aioobe Jun 06 '11 at 09:20
What are the collateral effects by using asList? Is made a copy of original array on memory? – richardaum Jun 13 '14 at 17:26
@Richard - No copy is made. The 'asList' List is a wrapper for the original array. Read the javadocs!! – Stephen C Jun 14 '14 at 01:48

score 4 · Answer 3 · edited Apr 24 '16 at 17:42

4

Arrays do not have an indexOf() method; however, java.util.List does. So you can wrap your array in a list and use the List methods (except for add() and the like):

output.add("1 2 3 4 5 6 7 8 9 10");  
String bigger[] = output.get(i).split(" ");
int biggerWhere = Arrays.asList(bigger).indexOf("10");

edited Apr 24 '16 at 17:42

Be Kind To New Users

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answered Jun 06 '11 at 09:18

Costi Ciudatu

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score 3 · Answer 4 · answered Jun 06 '11 at 09:36

3

You can use java.util.Arrays.binarySearch(array, item); That will give you an index of the item, if any...

Please note, however, that the array needs to be sorted before searching.

Regards

answered Jun 06 '11 at 09:36

Andrew

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score 2 · Answer 5 · answered Oct 19 '16 at 05:51

2

There is no direct indexOf method in Java arrays.

answered Oct 19 '16 at 05:51

abhishek58g

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score 0 · Answer 6 · edited Apr 07 '14 at 06:18

0

output.add("1 2 3 4 5 6 7 8 9 10");

you miss a " after 10.

edited Apr 07 '14 at 06:18

Ashwini Chaudhary

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answered Jun 06 '11 at 09:22

ChandlerSong

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indexOf in a string array

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