Easy you are looking for this:
java.util.List<java.util.Map.Entry<String,Integer>> pairList= new java.util.ArrayList<>();
How can you fill it?
java.util.Map.Entry<String,Integer> pair1=new java.util.AbstractMap.SimpleEntry<>("Not Unique key1",1);
java.util.Map.Entry<String,Integer> pair2=new java.util.AbstractMap.SimpleEntry<>("Not Unique key2",2);
pairList.add(pair1);
pairList.add(pair2);
This simplifies to:
Entry<String,Integer> pair1=new SimpleEntry<>("Not Unique key1",1);
Entry<String,Integer> pair2=new SimpleEntry<>("Not Unique key2",2);
pairList.add(pair1);
pairList.add(pair2);
And, with the help of a createEntry method, can further reduce the verbosity to:
pairList.add(createEntry("Not Unique key1", 1));
pairList.add(createEntry("Not Unique key2", 2));
Since ArrayList isn't final, it can be subclassed to expose an of method (and the aforementioned createEntry method), resulting in the syntactically terse:
TupleList<java.util.Map.Entry<String,Integer>> pair = new TupleList<>();
pair.of("Not Unique key1", 1);
pair.of("Not Unique key2", 2);
Yes, Blah.valueOf("A") will give you Blah.A.
Note that the name must be an exact match, including case: Blah.valueOf("a") and Blah.valueOf("A ") both throw an IllegalArgumentException.
The static methods valueOf() and values() are created at compile time and do not appear in source code. They do appear in Javadoc, though; for example, Dialog.ModalityType shows both methods.
Best Solution
For a quick solution, just use hash tables, as has been mentioned before.
However, if you prefer a more principled approach, you can take a look at FSet, which is “a functional set-theoretic collections library”. Among others, it contains classes and operations for sets and bags.
(EDIT:) The cleanest way would probably be to define your set-oriented operations as generic functions. A set of generic functions is basically equivalent to a Java interface, after all. You can simply implement methods on the standard HASH-TABLE class as a first prototype and allow other implementations as well.