Someone has to have asked this before, but I can't find it :-(. Does Java have a built-function to allow me to linearly search for an element in an array or do I have to just use a for loop?
+3
A:
Use a for loop. There's nothing built into array. Or switch to a java.util Collection class.
duffymo
2010-08-01 23:59:42
+6
A:
You might want to consider using a Collection implementation instead of a flat array.
The Collection interface defines a contains(Object o) method, which returns true/false.
ArrayList implementation defines an indexOf(Object 0), which gives an index, but that method is not on all collection implementations.
Both these methods require proper implementations of the equals method, and you probable want a properly implemented hashCode method just in case you are using a hash based Collection (e.g. HashSet).
hvgotcodes
2010-08-02 00:00:07
+2
A:
You can use one of the many Arrays.binarySearch() methods. Keep in mind that the array must be sorted first.
krock
2010-08-02 00:01:44
That's an option only is elements of array are comparable themselves.
Nikita Rybak
2010-08-02 00:02:28
We can only assume that this is the case, e.g. an array of ints, Strings, etc. You could always provide a custom [`Comparator`](http://download.oracle.com/javase/6/docs/api/java/util/Comparator.html) to sort and search if needed.
krock
2010-08-02 00:13:33
+2
A:
There is a contains method for lists, so you should be able to do:
Arrays.asList(yourArray).contains(yourObject);
Warning: this might not do what you (or I) expect, see Tom's comment below.
Douglas
2010-08-02 00:01:45
Thats pretty short, but this use case is common enough that they really should have added a function into the language
Casebash
2010-08-02 00:15:43
@Casebash It compiles but doesn't do what you expect. Because of evil varargs, the argument gets treated as an array of arrays of primitives.
Tom Hawtin - tackline
2010-08-02 02:08:01