Code Challenge — Write a program

Write a class named AsciiCharSequence that implements compact storage of ASCII-character sequences. Their codes can be stored in one single byte, unlike Unicode characters. Compared to the standard String class, your class will require twice less memory (before Java 9).

The class AsciiCharSequence should:

implement the interface java.lang.CharSequence; have a constructor that takes a byte array; define methods length, charAt, subSequence, and toString. You can find the declaration of methods and their behavior in the description of java.lang.CharSequence (JavaDoc or sources). Carefully check signatures of abstract methods of java.lang.CharSequence interface, especially subSequence method. It accepts 2 integers: start index (inclusive) and end index (!exclusive). The method returns an object of a class that implements java.lang.CharSequence interface. For example, it can be an instance of AsciiCharSequence class.

Note: the testing system will always pass correct input parameters to overridden methods.

P.S. The feature is supported since Java 9 in standard strings. For details, see this article on compact strings in Java 9.

class AsciiCharSequence implements CharSequence{

    private byte[] value;

    public AsciiCharSequence(byte[] value) {
        this.value = value;

    }

    @Override
    public int length() {
        return value.length;
    }

    @Override
    public char charAt(int index) {
        return (char) value[index];
    }

    @Override
    public String toString() {
        return new String(this.value);
    }

    @Override
    public AsciiCharSequence subSequence(int start, int end) {


           byte[] result;
           result = new byte[end - start];
           for (int i = start; i < end; i++) {
               result[i - start] = value[i];
            }
            AsciiCharSequence asciiCharSequence = new AsciiCharSequence(result);
            return asciiCharSequence;
        }



}