CODEWITHSUNDEEP
java
Karol Kreczman
Karol Kreczman

Reputation: 3

JAVA checking if an array contains a value diffrent than the value given

I have a declaration of a ArrayList T

ArrayList<Integer> T = new ArrayList<Integer>();

And i have a while loop which should be active until the list will be composed of only -1 int's. Currently it looks like this:

 while(T.contains(!-1))

As you probably guessed it. It does not work properly since i can't use negation on a integer.

Upvotes: 0

Views: 54

Answers (4)

volatilevar
volatilevar

Reputation: 1676

If you want to repetitively check whether there are elements that are not -1 in the list, you can do it as below for efficiency:

  1. Count the number of elements that are not -1 and store this value in n
  2. while (n > 0) { do stuff; and decrease n if the value of an element becomes -1 }

Upvotes: 0

davidxxx
davidxxx

Reputation: 131346

But the loop has to end only if the ENTIRE list is made of -1's.

You could use a HashSet that will remove all duplicated elements in the List.
if the HashSet object has a size of 1 (it means that the list contains only the same value) and if the first element of the list is -1, it means that the list contains only -1 values.

List<Integer> integers = new ArrayList<Integer>();

while (!(new HashSet<Integer>(integers).size() == 1 && integers.get(0).intValue() == -1)){
     ....
 }

Upvotes: 0

ΦXocę 웃 Пepe&#250;pa ツ
ΦXocę 웃 Пepe&#250;pa ツ

Reputation: 48258

you can stream the list:

List<Integer> myList = ...;
myList = myList.stream().filter(x -> x < 0).collect(Collectors.toList());
System.out.println(myList);

Upvotes: 0

Ousmane D.
Ousmane D.

Reputation: 56423

You can use Stream#allMatch.

while(!T.stream().allMatch(i -> i == -1)){ // note the ! operator to negate the result
       //do something              
}

This should keep looping until the list will be composed of only -1 ints as you've suggested.

Upvotes: 2

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