Question

The String class is provided in the Java library.

Provide your own implementation (name the new class MyString2) with one data field, array of

characters, and the following methods:

 public MyString2(String s); constructor

 public MyString2 substring(int begin); create a new string starts at begin and return it.

 public MyString2 toUpperCase(); convert all characters in a string to uppercase and return it.

 public char[] toChars(); return string as an array of characters.

 public static MyString2 valueOf(boolean b); convert b value to string and return it.

Do not use any method from String, StringBuilder, or StringBuffer

Answer 1

public class MyString2 {

    private char[] data;

    public MyString2() {
        this.data = new char[0];
    }

    public MyString2(String s) {
        data = new char[s.length()];
        for (int i = 0; i < s.length(); i++) {
            data[i] = s.charAt(i);
        }
    }

    public MyString2 substring(int begin) {
        char[] result = new char[data.length - begin];
        for (int i = begin; i < data.length; i++) {
            result[i - begin] = data[i];
        }
        MyString2 myString = new MyString2();
        myString.data = result;
        return myString;
    }

    public MyString2 toUpperCase() {
        char[] result = new char[data.length];
        for (int i = 0; i < data.length; i++) {
            result[i] = Character.toUpperCase(data[i]);
        }
        MyString2 myString = new MyString2();
        myString.data = result;
        return myString;
    }

    public char[] toChars() {
        char[] result = new char[data.length];
        for (int i = 0; i < data.length; i++) {
            result[i] = data[i];
        }
        return result;
    }

    public static MyString2 valueOf(boolean b) {
        if (b) {
            return new MyString2("true");
        } else {
            return new MyString2("false");
        }
    }
}