/*
 * [TestTreeMap.java]
 *
 * Summary: Example use of java.util.TreeMap.
 *
 * Copyright: (c) 2010-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.0 2010-02-25 initial version
 */
package com.mindprod.example;

import java.util.Collection;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

import static java.lang.System.*;

/**
 * Example use of java.util.TreeMap.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.0 2010-02-25 initial version
 * @see TestHashMap
 * @since 2010-02-25
 */
public final class TestTreeMap
    {
    /**
     * Sample code to TEST TreeMap.
     *
     * @param args not used
     */
    public static void main( String[] args )
        {
        // create a new TreeMap
        TreeMap<String, String> t = new TreeMap<>( /* no size estimates needed */ );
        // add some key/value pairs to the TreeMap
        t.put( "WA", "Washington" );
        t.put( "NY", "New York" );
        t.put( "RI", "Rhode Island" );
        t.put( "BC", "British Columbia" );
        t.put( "NC", "North Carolina" );
        t.put( "NE", "Nebraska" );
        // look up a key in the TreeMap
        String stateName = t.get( "NY" );
        // prints "New York"
        out.println( stateName );
        out.println( "enumerate all the keys in the TreeMap, by key" );
        // keySet gives you a Set, which is not a List.
        // If you need something you can sort, use toArray.
        // If you need a List, then use Arrays.asList.
        for ( String key : t.keySet() )
            {
            String value = t.get( key );
            // prints lines of the form NY New York
            // in key order, unlike a HashMap
            out.println( key + " " + value );
            }
        out.println( "enumerate all the values in the TreeMap, by key, note values out of order" );
        // values gives you a Collection which is not a List.
        // If you need something you can sort, use to Array.
        // If you need a List, then use Arrays.asList.
        // prints lines of the form New York
        // in key order, unlike a HashMap
        // lamba to println each String in t.values
        t.values().forEach( out::println );
        out.println( "enumerate all the key/value Entries in the TreeMap, by key" );
        // This gives you a Map of Entry items. This is not suitable for sorting.
        for ( Map.Entry<String, String> entry : t.entrySet() )
            {
            // prints lines of the form NY=New York
            // in key order, unlike a HashMap
            out.println( "as Entry: " + entry );
            // this does not require an expensive get lookup to find the value.
            String key = entry.getKey();
            String value = entry.getValue();
            out.println( "separately: " + key + " " + value );
            }
        out.println( "extract the keys into an array" );
        // actual type is a private nested static class TreeMap.KeySet
        // This Set is not Serializable.
        Set<String> justKeys = t.keySet();
        // Use toArray that takes an skeleton String[] array,
        // otherwise we end up with a useless Object[] instead of a String[].
        final String[] keys = justKeys.toArray( new String[ justKeys.size() ] );
        out.println( "extract values into an array, may contain duplicates unlike a Set." );
        // the actual type is a private nested static class TreeMap.Values
        // This Collection is not Serializable.
        final Collection<String> justValues = t.values();
        final String[] values = justValues.toArray( new String[ justValues.size() ] );
        out.println( "extract key/value pair entries into an array." );
        final Set<Map.Entry<String, String>> justEntries = t.entrySet();
        @SuppressWarnings( "unchecked" ) final Map.Entry<String, String>[] keyValuePairs =
                justEntries.toArray( new Map.Entry[ justEntries.size() ] );
        // Infuriatingly, this generates an unchecked conversion warning message.
        // Type erasure won't let us say:
        // Map.Entry<String, String>[] keyValuePairs =
        // justEntries.toArray ( new Map.Entry<String,String>[justEntries.size()] );
        // There might be some clever way of using Class.asSubclass to mollify the compiler.
        // There so many times when generics create more problems than they solve.
        }
    }