ArrayList search value

Question

I have an arraylist which is conformed of objects which have a name and a value so the arraylist is:

name  value
A     1
B     10
C     23
D     45

How would you loop the ArrayList searching for 2 names like C and D, and get their respective values: 23, and 45?

What kind of objects are in the list? Your "structure" is unclear to those of us to can't see your code. — Matt Ball
– Matt Ball, Commented Mar 30, 2011 at 0:12
Sorry, what? Arraylist is not key->value like a HashMap or similar is. Your question makes no sense. — Chris Dennett
– Chris Dennett, Commented Mar 30, 2011 at 0:13
Are your name-value pairs stored in an object that you've defined? ArrayLists typically take a single data type e.g. ArrayList<Integer> or ArrayList<String>, unless you've defined some kind of object that has both as instance variables. You might want to investigate the HashMap<ElemType, ElemType> collection class instead. — Zkoh
– Zkoh, Commented Mar 30, 2011 at 0:14
Yes my arraylist is of type node wich has several elements, but I am only interested in name and value.. — edgarmtze
– edgarmtze, Commented Mar 30, 2011 at 0:29

Dimitar · Accepted Answer · 2011-03-30 00:26:15Z

7

I'm assuming you mean that you have objects in the array list which have a name and value?

You could do something like this:

for(MyObj obj : list) {
    if(obj.getName().equals("C") || obj.getName().equals("A")){
          System.out.println("Value: " + obj.getValue);
    }
}

But your best bet may be to create a Hashmap of String to value:

Map<String, Integer> valueMap = new HashMap<String, Integer>();

Then you can simply call

valueMap.get("A");

which will return the value associated with A.

edited Mar 30, 2011 at 0:26

answered Mar 30, 2011 at 0:20

Dimitar

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6 Comments

Chris Dennett Over a year ago

How is that supposed to work? Object has no method 'getName()'. You'd have to create a subclass and implement that method.

Dimitar Over a year ago

Ah yeah, sorry I wrote object when it should have been anything else.

edgarmtze Over a year ago

Map<String, int> valueMap = new HashMap<String, int>(); get me an error int, how to declare it

Dimitar Over a year ago

oh sorry it should be Integer rather than int.

edgarmtze Over a year ago

and how do I insert elements in hash

|

fastcodejava · Accepted Answer · 2011-03-30 00:13:11Z

0

for (MyObj obj : list) {
    // Here check if obj.getAAA() equals to "C" etc
}

answered Mar 30, 2011 at 0:13

fastcodejava

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