How to implement Map in singleton class?
<p>I have the task to make a program about Florist's. I have to make a class PriceList, which is a singleton. I have also a following given testing function main:</p>

<pre><code> public static void main(String[] args) {
 PriceList pl = PriceList.getInstance();
 pl.put("rose", 10.0);
 pl.put("lilac", 12.0);
 pl.put("peony", 8.0);
</code></pre>

<p>Looking on these pl.puts(), I decided to implement Map interface in class PriceList, but I don't know exactly how to do it, when I have only one object of this class and it has to be a Map. I have already written that much and don't know what to do next:</p>

<pre><code>public class PriceList &lt;String, Double&gt;  implements Map &lt;String, Double&gt; {

private static PriceList instance = null;

protected PriceList() {}

public static PriceList getInstance() {
    if (instance == null)
        instance = new PriceList();
    return instance;
}

public void put(String string, double d) {
    // TODO Auto-generated method stub

}}
</code></pre>

<p>Thanks in advance for any help!</p>