Check if a variable is equal to a list in java

Question

I want to check if the variable foo is equal to a list of values in java

if( foo == "Cheese" || foo == "a" || foo == "3" ) {
    // ...
}

I want to know how to do something like the following :

String[] values = {"Cheese", "a", "3"};
if( foo in values ) {
    // ...
}

Thank you for helping me !

`List.contains()`? Or maybe `List.equals()`, depending one what you actually mean by `foo==1` etc. — markspace, Oct 24 '17 at 17:58
Do you mean like the SQL `IN` keyword? Like `field in (1,2,3)` ? — fvu, Oct 24 '17 at 18:02
fvu – yes like the IN in SQL and i think there is one in python. markspace – Oh i didn't know List.equals() had this behavior i will try now. cpp beginner – I know the list in advance. — Alban, Oct 24 '17 at 18:04
I don't speak Python, so you're going to have to explain in Java what you want. If you thought I was referring to Python methods, I wasn't. That's Java. — markspace, Oct 24 '17 at 18:06
Don't use an array Use a HashSet. Then use its contains() method. Arrays should generally be avoided in Java. Collections are much more powerful (and safe). — JB Nizet, Oct 24 '17 at 18:06
contains shows me an error and equals does nothing, my list is a String[] and i want to know if my string is contained in this list — Alban, Oct 24 '17 at 18:11
Loop through `values` with a for each loop. `for (String i : values)`. Then just use a `if` statement. `if (i.equals(foo))`. `return true` — drewteriyaki, Oct 24 '17 at 18:13
if (Arrays.asList("1", "2", "3").contains(foo)) does not give a compilation error. — cpp beginner, Oct 24 '17 at 18:13
*my list is a String[]*: then it's not a list. It's an array. A List and an array are not the same thing. Use collections, not arrays. Google for "Java collections tutorial". — JB Nizet, Oct 24 '17 at 18:15
Thank you @drewteriyaki, your solution works. JB Nizet i didn't know about that i will follow a tutorial like you said. — Alban, Oct 24 '17 at 18:40
You should read https://stackoverflow.com/questions/513832/how-do-i-compare-strings-in-java — Raedwald, Oct 25 '17 at 08:21
Possible duplicate of [Compare one String with multiple values in one expression](https://stackoverflow.com/questions/10205437/compare-one-string-with-multiple-values-in-one-expression) — Tom, Oct 25 '17 at 21:49

score 1 · Answer 1 · answered Oct 24 '17 at 18:13

You can do this by using the contains() method of List.

String values[] = {"Cheese", "a", "3"};
String foo = "a";
String bar = "b";
List<String> list = Arrays.asList(values);
System.out.println(list.contains(foo)); // true;
System.out.println(list.contains(bar)); // false;

score 0 · Answer 2 · answered Oct 25 '17 at 21:48

use contains() in List

    String[] values = {"Cheese", "a", "3"};
    String foo = "3";
    List<String> valuesAsList = Arrays.asList(values);

    boolean containsFoo = valuesAsList.contains(foo);
    System.out.println("foo contained in list " + containsFoo);

score -4 · Accepted Answer · answered Oct 24 '17 at 18:03

-4

String[] values = {"Cheese", "a", "3"};
boolean isIn = false;
for (String str : values) {
   if (str == foo) {
      isIn = true;
      break;
   }
}

(Or use str.equals(foo) depending on what you want)

answered Oct 24 '17 at 18:03

Ltei

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You do know that using `==` to compare strings in Java is not advisable, and that you should use the `equals` method instead, right? – Mark Rotteveel Oct 27 '17 at 19:39

Check if a variable is equal to a list in java

3 Answers3