Initializing empty instance variables in constructor

I have a LogAnalyzer class that looks at a web server log, creates LogEntry objects and puts those objects into HashMaps for analyzing.

My LogAnalyzer class has these fields:

private int totalVisits;
private int uniqueVisits;
private ArrayList<LogEntry> records;
private HashMap<String, ArrayList<LogEntry>> uniqueIPs; //<address, log entries>
private HashMap<String, ArrayList<LogEntry>> dailyRecords; // <date, log entries>

My constructor looks like this:

public LogAnalyzer() {

    records = new ArrayList<>();
    dailyRecords = new HashMap<>();
    uniqueIPs  = new HashMap<>();

}

And then I have this method:

public void initializeRecords(String path){
    readFile(path); //reads the web log file and fills out the records and dailyRecords fields
    getUniqueIPs(); //fills out the uniqueIPs HashMap field.
    uniqueVisits = uniqueIPs.size(); //fills out the uniqueVisits field
    totalVisits = records.size(); //fills out the totalVisits field
}

So my question:

I have read (but don't really understand) it's "bad" to call methods inside the constructor. However it seems like the constructor is pointless here, since it is actually the initializeRecords that is doing all of the meaningful work of "creating" the object.

I don't have the background in Java or programming to understand the explanations I've found so far. There is a lot of talk of overriding things, and I think that's what I'm not clear on. I'm wondering why I should keep my constructor and this method seperated, in simple terms that a beginner can understand.

**EDIT: ** Here's the code for readFile():

public void readFile(String filename) {
    FileResource fr = new FileResource(filename);
    for (String line : fr.lines()){
        LogEntry le = WebLogParser.parseEntry(line);
        String date = le.getAccessTime().toString().substring(4, 10);
        if (dailyRecords.keySet().contains(date)){
            dailyRecords.get(date).add(le);
        }
        else{
            ArrayList<LogEntry> entries = new ArrayList<>();
            entries.add(le);
            dailyRecords.put(date, entries);
        }
        records.add(le); 
    }