Part (a)

Write the decodeString method that reconstructs a string from encoded StringPart objects.

Solution

public String decodeString(ArrayList parts)
{
    String decoded = "";
    for (StringPart sp : parts)
    {
        decoded += masterString.substring(
            sp.getStart(),
            sp.getStart() + sp.getLength());
    }
    return decoded;
}

Part (b)

Write the encodeString method that encodes a word using parts from the master string.

Solution

public ArrayList encodeString(String word)
{
    ArrayList parts = new ArrayList();
    int pos = 0;
    while (pos < word.length())
    {
        StringPart part = findPart(word.substring(pos));
        parts.add(part);
        pos += part.getLength();
    }
    return parts;
}

Key Concepts

Common Mistakes