Find if a String is present in an array [duplicate]

37

This question already has an answer here:

OK let's say I have an array filled with {"tube", "are", "fun"} and then I have a JTextField and if I type either one of those commands to do something and if NOT to get like a message saying "Command not found".

I tried looking in Java docs but all I am getting is things that I don't want like questions and stuff... so, how is this done? I know there is a "in array" function but I'm not too good with combining the two together.

Thanks.

Here is what I have so far:

String[] dan = {"Red", "Orange", "Yellow", "Green", "Blue", "Violet", "Orange", "Blue"};
boolean contains = dan.contains(say.getText());

but I am getting cannot find symbol in dan.contains

nn2

출처 java arrays

5 답변

62

This is what you're looking for:

List<String> dan = Arrays.asList("Red", "Orange", "Yellow", "Green", "Blue", "Violet", "Orange", "Blue");

boolean contains = dan.contains(say.getText());

If you have a list of not repeated values, prefer using a Set<String> which has the same contains method

  • yep! see my example. :D - nn2
  • That's because an array is not a set - Pablo Fernandez
  • @Dan - BZZZT - you are trying to invoke contains on an array, not a Set!!! - Stephen C
  • THANKS SIMPSO- I MEAN PABLO! :D Tahnks Stephen. Rookie mistake. - nn2
31
 

String[] a= {"tube", "are", "fun"};
Arrays.asList(a).contains("any");

  • thanks... great example - Antonio
  • THIS is what I was looking for. Simple ! - ether_joe
7

Use Arrays.asList() to wrap the array in a List<String>, which does have a contains() method:

Arrays.asList(dan).contains(say.getText())

3

This can be done in java 8 using Stream.

import java.util.stream.Stream;

String[] stringList = {"Red", "Orange", "Yellow", "Green", "Blue", "Violet", "Orange", "Blue"};

boolean contains = Stream.of(stringList).anyMatch(x -> x.equals(say.getText());

  • This is the best answer. The others fail because asList returns non-parameterized generic. - John Henckel
1

If you can organize the values in the array in sorted order, then you can use Arrays.binarySearch(). Otherwise you'll have to write a loop and to a linear search. If you plan to have a large (more than a few dozen) strings in the array, consider using a Set instead.

  • Erm, would it matter if I said that the array would be permnant and not changed at a order at all? Would there be an easier way than? - nn2
  • @Dan - I think his first sentence answers that. You do know how to sort strings by hand, don't you? - Stephen C
  • @Jim, this answer is incorrect. The documentation of #binarySearch explicitly states: "If the array contains elements that are not mutually comparable (for example, strings and integers), it cannot be sorted according to the natural ordering of its elements, hence results are undefined." DO NOT use binarySearch on Integer or String, or any elements that can at most have a partial order. - Aleksandar Dimitrov

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