builder for HashMap

Question

Guava provides us with great factory methods for Java types, such as Maps.newHashMap().

But are there also builders for java Maps?

HashM         


        

Answer 1

I had a similar requirement a while back. Its nothing to do with Guava but you can do something like this to be able to cleanly construct a Map using a fluent builder.

Create a base class that extends Map.

public class FluentHashMap extends LinkedHashMap {
    private static final long serialVersionUID = 4857340227048063855L;

    public FluentHashMap() {}

    public FluentHashMap delete(Object key) {
        this.remove(key);
        return this;
    }
}

Then create the fluent builder with methods that suit your needs:

public class ValueMap extends FluentHashMap {
    private static final long serialVersionUID = 1L;

    public ValueMap() {}

    public ValueMap withValue(String key, String val) {
        super.put(key, val);
        return this;
    }

... Add withXYZ to suit...

}

You can then implement it like this:

ValueMap map = new ValueMap()
      .withValue("key 1", "value 1")
      .withValue("key 2", "value 2")
      .withValue("key 3", "value 3")