Need help writing a program for #3 in Java!

3. Design a class named MyString to provide your own implementation which is similar to Java String class. The class contains the following methods: public MyString(char [] chars) - constructor public char charAt(int index) public int length() public MyString substring(int begin) public MyString substring(int begin, int end) public MyString toLowerCase() public MyString toUpperCase() public boolean equals(MyString str) public static MyString valueOf(int i) public static MyString valueOf(double d) Write program to test your own MyString class