CODEWITHSUNDEEP
java
Badman
Badman

Reputation: 417

How to add list of items to an ArrayList<String> in java?

I have list of words which I need to load to ArrayList< String >

prefix.properties

vocab\: = http://myweb.in/myvocab#
hydra\: = http://www.w3.org/ns/hydra/core#
schema\: =  http://schema.org/

"vocab:" is actually "vocab:" .Slash(\) is used to read colon(:) character because it is special character.

Dictionary.java

public class Dictionary {
    public static ArrayList<String> prefix = new ArrayList<>();
    static {
        Properties properties = new Properties();
        InputStream input = null;
        input = ClassLoader.getSystemResourceAsStream("prefix.properties");
        System.out.println(input!=null);
        try {
            properties.load(input);
        } catch (IOException e) {
            e.printStackTrace();
        }
        Set<Map.Entry<Object, Object>> entries = properties.entrySet();
        for(Map.Entry<Object, Object> E : entries)
        {
            prefix.add(E.getKey().toString());
            prefix.add(E.getValue().toString());
        }
    }
}

In Dictionary.java , ArrayList prefix will have

prefix = [
           "vocab:",
           "http://myweb.in/myvocab#",
           "hydra:",
           "http://www.w3.org/ns/hydra/core#",
           "schema:",
           "http://schema.org/"
         ]

I am querying some data in another class. For eg:

public class QueryClass
{
    public ArrayList<String> queryResult(String findKey)
    {
       ArrayList<String> result = new ArrayList<String>();

       ArrayList<String> prefix = Dictionary.prefix;
       Iterator<String> iterator = prefix.iterator();

       while (iterator.hasNext())
       {
           String currentKey = iterator.next()+findKey;
           /**
               Here my logic to search data with this currentKey
           */
       }
       return result;
    }
}

Problem :
I want to avoid this method to load from .properties file because there is possibility of odd number of elements can be present while .properties file provide (key,value) pair way to store data.


Reason why I have to load from separate file ? Because In future I will have to add more keywords/String thats why I put it in prefix.properties file.


Is there any alternative way to do this?

Upvotes: 0

Views: 195

Answers (2)

GhostCat
GhostCat

Reputation: 140447

Do not re-invent the wheel.

If you can define the file format, then just go for java properties.

You see, the Properties class has a method getProperty(String, String) where the second argument can be used to pass a default value for example. That method could be used in order to fetch keys that don't come with values.

I would be really careful about inventing your own format; instead I would look into ways of re-using what is already there. Writing code is similar to building roads: people forget that each new road that is built translates to maintenance efforts in the future.

Besides: you add string values to a list of strings by calling list.add(strValue). That is all that is to that.

Edit on your comment: when "java properties" are not what you are looking for; then consider using other formats. For example you could be persisting your data in some JSON based format. And then just go for some existing JSON parser. Actually, your data almost looks like JSON already.

Upvotes: 3

Earguay
Earguay

Reputation: 58

I'm not sure why you need to use ArrayList but if you want to pass these property keys/values, there are 2 better ways:

  1. Use Properties itself.
  2. Convert to HashMap.

Upvotes: 0

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