Loading a map using Properties class

Question

I have a map with 75000 entries and each entry value will be of size 10kb on average.

I load this map into memory using Properties class . But due to the size of the

Answer 1

I assume you don't need to load all the properties at the same time, but you rather need to iterate through all properties. Personally, I would go with parsing manually the file line by line and working in a stream-like fashion. If there is a lib for processing very large property I don't know it.

Answer 2

Don't use Properties, which is legacy

1. Divide entries into multiple files

2. Read each file in sequence, load and process using Preferences

Example code:

package com.mypack.test;

import java.io.*;
import java.util.*;
import java.util.prefs.Preferences;

public class PreferencesExample {

    public static void main(String args[]) throws FileNotFoundException {
        Preferences ps = Preferences.userNodeForPackage(PreferencesExample.class);
        // Load file object
        File fileObj = new File("d:\\data.xml");
        try {
            FileInputStream fis = new FileInputStream(fileObj);
            ps.importPreferences(fis);
            System.out.println("Prefereces:"+ps);
            System.out.println("Get property1:"+ps.getInt("property1",10));

        } catch (Exception err) {
            err.printStackTrace();
        }
    }
}

Sample xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE preferences SYSTEM 'http://java.sun.com/dtd/preferences.dtd'>
<preferences EXTERNAL_XML_VERSION="1.0">
<root type="user">
<map />
<node name="com">
  <map />
  <node name="mypack">
    <map />
    <node name="test">
      <map>
        <entry key="property1" value="80" />
        <entry key="property2" value="Red" />
      </map>
    </node>
  </node>
</node>
</root>
</preferences>