java - check if a substring is present in an arraylist of strings in java

Question

suppose i've an arraylist (arr1) with the following values:

"string1 is present"
"string2 is present"
"string3 is present"
"string4 is present"

i wanted to see if the substring 'string2' is present in this arraylist. by looping through the arraylist and using 'get' by index i extracted element at each index and then using 'contains' method for 'Strings' i'm searched for 'string2' and found a match

for (int i=0;i<arr1.size(); i++)
{
  String s1=arr1.get(i);
  if (s1.contains("string2"))
  {
    System.out.println("Match found");
  }
}

is there a way to use the 'contains' method of the arraylist itself and do the same instead of me looping through the arraylist and using the 'contains' method for 'String' to achieve this. Can someone please let me know.

Thanks

Sergey Kalinichenko · Accepted Answer · 2018-01-06 21:58:30Z

2

You cannot use contains method of ArrayList, because you cannot get around checking each string individually.

In Java 8 you can hide the loop by using streams:

boolean found = arr1.stream().anyMatch(s -> s.contains("string2"));

answered Jan 6, 2018 at 21:58

Sergey Kalinichenko

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Comments

Ousmane D. · Accepted Answer · 2018-01-06 22:33:33Z

1

Using the Stream API you could check if the list has an element which contains "string2" and print to the console like this:

arr1.stream()
    .filter(e -> e.contains("string2"))
    .findFirst()
    .ifPresent(e -> System.out.println("Match found"));

However, you cannot avoid checking each element individually (until we find the first) because you're interested to see if a particular string contains a specific substring.

edited Jan 6, 2018 at 22:33

answered Jan 6, 2018 at 22:07

Ousmane D.

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1 Comment

Michal Over a year ago

No it would not. filter(s->s.contains("string2") would.

Or251 · Accepted Answer · 2018-01-06 22:13:13Z

0

Here is another way (make a string out of the arrayList):

String listString = String.join(", ", arr1);

      if (listString.contains("string2"))
      {
        System.out.println("Match found");
      }

answered Jan 6, 2018 at 22:13

Or251

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2 Comments

Sergey Kalinichenko Over a year ago

This assumes that the search string does not contain commas :-)

Or251 Over a year ago

Yes! forgot to mention that. Be careful about it, and if it is with commas, just replace it with an unused character.

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