[FIXED] Two-dimensional ArrayList

Issue

Just a very small question... I seem to run into too much complexity here: I have to realize an index-structure like {42, someString}. I tried:

Object entry[][] = new Object[1][1];
ArrayList<Object> my_list = new ArrayList<Object>();

However that looks really strange. Isn't there a better much simpler solution to just store some Integer and a String? I need to perfrom search for the Strings and return the Integer... so I thought Collections and ArrayLists are good friends in the Java API.

Solution

Solution: use a Map

Uhm, do you perhaps need a Map?

Map<String,Integer> map = new HashMap<String,Integer>();
map.put("Some String", 42);
// or, more correctly:
map.put("Some String", Integer.valueOf(42));

You can search it using

Integer result = map.get("Some String");

Reference: Sun Java Tutorial > Collection Trail > Interfaces > The Map Interface

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Fixing the OP's Code

BTW, the code in the question is flawed. Here's how you would do it if you wanted to use a List of object arrays (which you shouldn't):

// single dimension, not multi-dimension
Object[] entry = new Object[]{"Some String",Integer.valueOf(42)};
// use interface as variable, not implementation type
// generic type is object array, not object
List<Object[]> myList = new ArrayList<Object[]>();
// add array to list
myList.add(entry);

Now you could search like this:

for(final Object[] candidate : myList){
    if("Some String".equals(candidate[0])){
        System.out.println("Result: " + candidate[1]);
        break;
    }
}

However, this is just for reference, don't do it this way. The Collections Framework contains solutions for almost all standard cases. Use a Map.

Answered By - Sean Patrick Floyd
Answer Checked By - Mary Flores (JavaFixing Volunteer)