Multidimensional Arrays to store multiple data types

Question

I know php a little. and java much little.

I am creating a small application to search a text in a text area and store the result in a array.

The array in PHP will look like this.

array(
    "searchedText" => "The text that is searched",
    "positionsFound" => array(12,25,26,......),
    "frequencies" => 23 //This is total words found divided by total words
);

But, java does not support array with multiple data types. In the above array, only the second element "positionFound" is of variable length.

Later on I need to iterate through this array and create a file including all above mentioned elements.

Please guide me

Can I suggest that you take the time to read the Sun Java Tutorial starting with the "New To Java" page - oracle.com/technetwork/topics/newtojava/new2java-141543.html. In the long term this will save you lots of pain ... — Stephen C
– Stephen C, Commented May 11, 2011 at 10:54

Peter Lawrey · Accepted Answer · 2011-05-11 11:11:51Z

3

Java does support Objects. You have to define a Class like

class MyData {
    String searchedText;
    Set<Integer> positionsFound;
    int frequencies;
}

List<MyData> myDataList = new ArrayList<MyData>();
// OR
MyData[] myDataArray = new MyData[number];

And you can use this structure to hold your data. There are other methods which are helpful such as constructors and toString() and I suggest you use your IDE to generate those.

When writing this data to a file, you might find JSon a natural format to use.

I suggest you look at GSon which is a nice JSon library.

From the GSon documentation, here is an example

class BagOfPrimitives {
  private int value1 = 1;
  private String value2 = "abc";
  private transient int value3 = 3;
  BagOfPrimitives() {
    // no-args constructor
  }
}

(Serialization)

BagOfPrimitives obj = new BagOfPrimitives();
Gson gson = new Gson();
String json = gson.toJson(obj);

==> json is {"value1":1,"value2":"abc"}

Note that you can not serialize objects with circular references since that will result in infinite recursion.

(Deserialization)

BagOfPrimitives obj2 = gson.fromJson(json, BagOfPrimitives.class);

==> obj2 is just like obj

edited May 11, 2011 at 11:11

answered May 11, 2011 at 10:24

Peter Lawrey

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8 Comments

Thomas Over a year ago

You should add the outer array would then be similar to MyData[] myData.

mrN Over a year ago

Which package is set in? It is giving cannot find symbol error

Peter Lawrey Over a year ago

@mrN, java.util.Set My IDE just finds it for me and adds the import automagically. ;)

mrN Over a year ago

@Peter, Can you tell me the way to store the values in the two ways to have suggested. I am going nuts, trying to figure that out.

mrN Over a year ago

Which IDE are you using? I am using netbeans

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