Question

So currently, I am extracting two different attributes from an XML file in java that (for my project) are related to each other and just printing them out to the console. However, I want to be able to store these in a way in which referencing one value will retrieve it’s corresponding counterpart. For example:

Id: rId11 & Target: image3
Id: rId10 & Target: image2
Id: rId9 & Target: image1

With those 3 values, I’d want a way to store each line, but when I reference “rId” I could get it’s corresponding “Target” value. I was thinking about using either an array or an arrayList, but I’m not really sure which would be better for my purposes or how exactly I would go about referencing only one value and getting the other. Could anyone offer me some advice? Thank you in advance.

Answer 1

If your keys are unique, use a Map.

Map<String, String> mak = new HashMap<String, String>();
map.put("rId11","image3");
map.put("rId10","image2");
map.put("rId9","image1");

Reference:

• Java Tutorial > The Map
  Interface

Otherwise, create a custom Object that holds key and value and create a List (or Set???) of these.

public class Entry {
    private final String id;
    private final String value;
    public Entry(String id, String value) {
        this.id = id; this.value = value;
    }
    public String getId() { return id; }
    public String getValue() { return value; }
    // also implement equals() and hashCode(), please
}

List<Entry> entries = new ArrayList<Entry>();
entries.add(new Entry("rId11","image3"));

Reference:

• Java Tutorial > The List Interface
• Java Tutorial > The Set Interface