Question

I am working on a program where i am reading a file and extracting keywords and their count. Later i need to pick up word with topmost frequency and match them with a keyword.

I have stored all the keywords i have found in the file in String list.
I wish to sort these on basis of frequency. So if at index 17 i have a word “stack” with value at index 17 in other integer list to be maximum, i wish to take them to position 1.

I can sort these using collections.sort but it does not take care of other list.

Here is my code :

while(m.find()) 
    {
        if(keyword.contains(m.group()))
            {
            keywordcount.set(keyword.indexOf(m.group()),keywordcount.get(keyword.indexOf(m.group()))+1);
            //System.out.println("*"+m.group()+":"+keywordcount.get(keyword.indexOf(m.group())));
            }
        else
            {
            keyword.add(m.group());
            int var=keyword.indexOf(m.group());
            //System.out.println(m.group()+":"+var);
            keywordcount.add(var, 1);
            }
        //System.out.println(keyword.size()+"#"+keywordcount.size());                       
    }
    for(int i=0;i<keyword.size();i++)
    {
        System.out.print(keyword.get(i)+ ":" +keywordcount.get(i)+" ");
    }

Answer 1

Typically, one would put both the String and the Integer into a single class, and sort a list of instances of that class.

E.g.

class StringCount implements Comparable<StringCount> {
    private final String string;
    private final int count;

    public StringCount(String string, int count) {
        this.string = string;
        this.count = count;
    }

    @Override
    public int compareTo(StringCount right) {
        return this.count < right.count ? -1
             : this.count > right.count ? 1
             : 0;
    }

    // implement equals and hashCode too
    // if a.compareTo(b) == 0, then a.equals(b) should return true.

}

Then, you can create a List<StringCount> and call Collections.sort(stringCountList).

Note, that this will put the StringCount instances with the lowest values first, so they come out in ascending order.