How do I get object and not address without using String/ toString?

Question

I need to create my own String class called MyString without using default String class/vector API. I have to work on some required methods, and their return types are predetermined. I can add other methods as long as String is not used.

Expected use would be:

(at main) System.out.println(str.toLowerCase()) - returns lower case of str

When I want to work with toLowerCase() method with return type MyString, I can't return the object content but only return the address.

Normally, this problem would require modification of toString(), but since this method requires return type of String by default, I can't use modification of toString() for the assignment.

The assignment is supposed to be not so hard and should not require complex extensions. My constructor may be the problem, but I can't specify which part is.

Code

public class MyString {
private char value[];

MyString(char[] arr){
    this.value = Arrays.copyOf(arr, arr.length);
}

... 

MyString toLowerCase() { // can't change return type
    for (int i =0; i<value.length; i++) {
        if ((int)value[i] > 64 && (int)value[i] < 91) {
            value[i] = (char) (value[i]+32);
        }
    }
    return this; // this returns address, and I can't override toString
}

Answer 1

Problem with System.out.println(str.toLowerCase()) is it ends up calling PrintStream.println(Object o), but that method internally at some point calls o.toString() which uses code inherited from Object#toString() (since you couldn't override toString as it expect as result String which is forbidden in your project) which result in form TypeInfo@hexHashCode.

This means you can't use System.out.println(MyString).

BUT PrintStream (which instance is held by System.out) allows us to provide data to print in different forms. In this case you can use println(char[]). All you need to do is adding to MyString method like toCharArray() which would return (preferably a copy of) array of characters held by MyString class.

This way you can use it like System.out.println(myStringInstance.toCharArray()) so code from your main method would need to look like

System.out.println(str.toLowerCase().toCharArray());
//                                   ^^^^^^^^^^^--this should return char[]