java if a string contains a substring code example

Example 1: string contains specific word in java

str_Sample.contains("Example"));

Example 2: check if a string contains a character java

string.indexOf('a')

Example 3: string contains specific word in java

public boolean String.contains(CharSequence s);

Example 4: how to check if a string contains a character

public static boolean containsIgnoreCase(String str, char c) {
        str = str.toLowerCase();

        for (int i = 0; i < str.length(); i++) {
            if (str.charAt(i) == Character.toLowerCase(c)) {
                return true;
            }
        }
        
        return false;
    }