I give you an example:
Syntax of String contains method
public boolean String.contains(CharSequence s)
Parameters
String “e” − This is the sequence to search
Return Value
This method returns true only if this string contains “e” else false.
Exception
NullPointerException − if the value of the parameter is null.
Example
String yourSentence = "Hello world";
char yourChar = yourSentence.charAt(1);
String anotherSentence "Hello everyone";
boolean result = anotherSentence.contains(String.valueOf(yourChar)));