Sorting symbol table by value in java

Question

Symbol table give a result sorted by key but how can we sort the symbol table by values. I used Arrays.sort(st,st.get(key)) but gives me an error:

cannot find symbol: method sort(ST,java.lang.Integer)

---

My program look something like this. Still getting errors:

import java.util.Comparator;
import java.util.Arrays;

public class DictionaryCounter {

    private final String key;

    public DictionaryCounter (String key){
            this.key = key;
        }

    public static class Frequency implements Comparator<DictionaryCounter>{
        public int compare(DictionaryCounter x, DictionaryCounter y){
            return x.get(key).compareTo(y.get(key));
        }
    }

    public static void main(String[] args) {

        ST<String, Integer> st = new ST<String, Integer>();
        //String key;

        while (!StdIn.isEmpty()) {
            key = StdIn.readString();
            if (!st.contains(key))
            { st.put(key, 1); }
            else
            { st.put(key,st.get(key) + 1 ); }
        }

        Arrays.sort(st,new Frequency (key));
        for (String s: st.keys()) {
            System.out.println(s + " " + st.get(s));
        }
    }
}

Answer 1

You can't sort quite like that - you need to implement Comparator<T> - for example:

public class FooComparator implements Comparator<Foo> {

    private final String key;

    public FooComparator(String key) {
        this.key = key;
    }

    public int compare(Foo x, Foo y) {
        return x.get(key).compareTo(y.get(key));
    }
}

Then use:

Arrays.sort(st, new FooComparator(key));

(It's hard to guess at the types involved without more information, but hopefully this will give you enough of a start...)