Question

The user has to be able to pass the MyString object a char array like arr = {'g','o','o','d','b','y','e' }, or a string such as “hello”
I don’t know where to get started because I don’t know how to make a method that can receive a dual type..

Answer 1

Just overload your methods:

public static String foo(String s) {
    // do something 
}

public static String foo(char[] s) {
    return foo(new String(s));
}

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EDIT In your title you say method but in your example you show constructors. Regardless, the same idea can be applied to both.

public MyString(String s) {
    // do something
}

public MyString(char[] s) {
    this(new String(s));
}