Java string types

1.1 Immutable strings

First, I focus on immutable string types that implement the interface from the file ImmutableString.java:

package nl.mauritssilvis.types.java.string;

public interface ImmutableString {
    int getLength();

    boolean isEmpty();

    char getChar(int index);

    char[] toCharArray();
}

Objects of the above type know their length, allow random access to their characters and can be converted to character arrays. None of the supplied methods can change an object's contents.

1.1.1 An array of characters

One of the ways the above immutable string interface can be implemented relies on using an array of characters. Such an implementation is provided in the file ArrayString.java, which, in a condensed form, looks as follows:

package nl.mauritssilvis.types.java.string;

// Import statements

public class ArrayString implements ImmutableString {
    private final char[] chars;

    // A no-argument constructor and constructors accepting
    // char[], ImmutableString or regular Java String objects

    // Methods implementing the ImmutableString interface

    // Methods overriding some methods of the Object class
}

Unit tests confirm the functioning of this immutable string implementation.