Re: typesafe java.util.Map construction and initialization
Josef Svitak wrote:
If I have:
public class foo {
private interface BarIF { }
private class BarImplOne implements BarIF { public BarImplOne() {} }
private class BarImplTwo implements BarIF { public BarImplTwo() {} }
private java.lang.String keys[] = { "key1", "key2" };
private final bars[] = { new BarImplOne(), new BarImplTwo() };
private final java.util.Map<String, BarIF> theMap;
public foo() {
// Can I do this... (doesn't work)
theMap = new java.util.HashMap( keys, bars );
// instead of this? (works)
theMap.add( "key1", new BarImplOne() );
}
javac complains of not having a ctor for HashMap(String[], BarIF[]).
Yes, you can see that from the API docs.
You should be able to do is something like:
public class Foo {
private interface Bar { }
private class BarImplOne implements Bar { public BarImplOne() {} }
private class BarImplTwo implements Bar { public BarImplTwo() {} }
private final java.lang.String[] keys;
private final Bar[] bars;
private final java.util.Map<String, Bar> map;
public Foo() {
map = new java.util.LinkedHashMap<String, Bar>();
map.put("key1", new BarImplOne());
map.put("key2", new BarImplTwo());
int num = map.size();
keys = new String[num];
map.keySet().toArray(keys);
bars = new Bar[num];
map.values().toArray(bars);
}
public static void main(String[] args) {
Foo foo = new Foo();
System.out.println(foo.map);
System.out.println(java.util.Arrays.asList(foo.keys));
System.out.println(java.util.Arrays.asList(foo.bars));
}
}
Or you can write your own method to construct a map from two arrays
(which I wouldn't really recommend).
Tom Hawtin
--
Unemployed English Java programmer
http://jroller.com/page/tackline/