Java - Check if item is in array

Question

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In Java, how can I test if an Array contains a certain value?

I have an array setup as follows:

Material[] blockedlevel1 = {
            Material.mymaterialone, Material.mymaterialtwo  
        };

How do I see if a Material is in this array?

Look for it, I'd think. There's that "do loop" thingie. – Hot Licks Mar 15 '12 at 01:34 — Hot Licks, Mar 15 '12 at 01:34

score 8 · Accepted Answer · answered Mar 15 '12 at 01:36

8

How about looking for it in the array?

for (Material m : blockedlevel1) {
    if (m.equals(searchedMaterial)) { // assuming that equals() was overriden
        // found it! do something with it
        break;
    }
}

answered Mar 15 '12 at 01:36

Óscar López

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How would I set what "m" is so that I can compare it to the array? I need to check `Material block = event.getBlock().getType();` (that is my material). – DannyF247 Mar 15 '12 at 03:52
2

In the above loop, `m` gets bound to each of the array's elements in turn; you don't need to _set_ it, the `for` loop does it for you. What you need to take care of, is to provide a `searchedMaterial` against which you can compare (it'd be `block` in your example), to implement an `equals()` method in the `Material` class, and to do something inside the `if`, once you find the material. – Óscar López Mar 15 '12 at 04:00

score 3 · Answer 2 · answered Mar 15 '12 at 01:36

3

If you want an easy way to check if an element is part of a collection you should probably consider a different data-structure like Set (and use contains()). With Array you can only iterate over the elements and compare each one.

answered Mar 15 '12 at 01:36

moodywoody

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score 1 · Answer 3 · answered Mar 15 '12 at 01:42

1

How about looking for it using the Arrays class?

See Arrays#binarySearch

Or as someone suggested, turn your array into a List and use the contains() method. Remember that you may have to override the Material#equals method.

answered Mar 15 '12 at 01:42

Tom

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Java - Check if item is in array

3 Answers3