Java：String. How does the contains (string) function work in Java?

I know that the time complexity of brute force method is n * m (M is the length of the first string and N is the length of the other string), which is used to test whether the string contains another string. However, I wonder whether the existence is a better solution?

boolean contains(String input,String search)

Solution

You can take a look at source:

public boolean contains(CharSequence s) {
    return indexOf(s.toString()) > -1;
}