CODEWITHSUNDEEP
javascriptjavacollections
Katedral Pillon
Katedral Pillon

Reputation: 14864

Is there a JavaScript style Collection in Java

In JavaScript I can define the following collection with keys awaiting values

var items = {
                'book':null,
                'pen':null,
                'pencil':null,
                'chicken':null,
                'wallet':null
            };

Then when I am ready to add values to my collection, I can do for instance

for(var p in items){
  if(some condition){
     items[p]=someValue;
  }
}

Is there a way to do this with the same level of efficiency in java?

I know that in old Java I can combine a Map and a List to accomplish this, but are their new data structures in Java that can handle this? I am talking about Java 7 (or 8) perhaps? I am using Google App-Engine for my Java.

Upvotes: 2

Views: 89

Answers (2)

xaviert
xaviert

Reputation: 5932

EDIT: Updated my answer based on the latest comments.

You could perfectly use a HashMap to achieve the same effect. To iterate over the existing keys, use the Map#keySet method.

Map<String, String> map = new HashMap<String, String>();
map.put("book", null);
map.put("pen", null);

for (String key : map.keySet()) {
    map.put(key, "Some Value");
}

System.out.println(map);

Upvotes: 4

Suresh Atta
Suresh Atta

Reputation: 122006

You could try it this way, if you're looking for the same style. 

 HashMap<String, String > items  = new HashMap<String, String>(){{
        put("book",null);
        put("pen",null);
    }};

Later you can put again with keys.

items.put("book", "Some Bible");

It seems you are new to Java and both Collections. I'm highly recommend you to read the about HashMap more before proceeding.

Upvotes: 6

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