Check if String Array contains a Substring without loop

user5155835 :

I want to find a substring in an array of strings, without using loop. I'm using:

import java.util.Arrays;

public class MyClass {
    public static void main(String args[]) {

        String[] files = new String[]{"Audit_20190204_061439.csv","anotherFile"};
        String substring= ".csv";

        if(!Arrays.stream(files).anyMatch(substring::contains)) {
            System.out.println("Not found:" + substring);
        }
    }
}

I'm always getting Not found. What is wrong with the approach?

Eran :

You are checking whether the String ".csv" does not contain any of the elements of your Stream, which is the opposite of what you wanted.

It should be:

if (!Arrays.stream(files).anyMatch(s -> s.contains(substring))) {
    System.out.println("Not found:" + substring);
}

P.S. As commented, you can use noneMatch instead of anyMatch, which will save the need to negate the condition:

if (Arrays.stream(files).noneMatch(s -> s.contains(substring))) {
    System.out.println("Not found:" + substring);
}

and if the ".csv" substring should only be searched for in the end of the String (i.e. treated as a suffix), you should use endsWith instead of contains.