A simple Table for Java

Table.java

import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.function.Consumer;

/**
 * Created by Bruno on 01/03/2015.
 * 
 * Table with type R for rows, C for columns and V for values
 * 
 */
public class Table <R,C,V>
{
    Map<R, Map<C, V>> map ;

    public Table() {
        map = new HashMap() ;
    }

    private Map<C, V> getRowValuesInternal(R row, boolean createRow) {
        Map<C, V> rowValues = map.get(row) ;

        if (rowValues == null && createRow) {
            rowValues = new HashMap() ;
            map.put(row, rowValues) ;
        }

        return rowValues ;
    }

    public Map<C, V> getRowValues(R row) {
        return getRowValuesInternal(row, false) ;
    }

    public boolean containsRow(R row) {
        return map.containsKey(row) ;
    }

    public V get(R row, C column) {
        if ( containsRow(row) ) {
            return getRowValues(row).get(column) ;
        } else {
            return null ;
        }
    }

    public void put(R row, C column, V value) {
        getRowValuesInternal(row, true).put(column, value) ;

    }

    public Set<Map.Entry<R, Map<C, V>>> entrySet() {
        return map.entrySet() ;
    }

    public void forEachRow(Consumer<Map.Entry<R, Map<C, V>>> consumer) {
        map.entrySet().forEach(consumer) ;
    }

    public void forEachColumn(Consumer<Map.Entry<C, Map<R, V>>> consumer) {
        this.reverseMap().entrySet().forEach(consumer);
    }

    private Map<C, Map<R, V>> reverseMap() {
        Map<C, Map<R, V>> reverseMap = new HashMap() ;

        for (Map.Entry<R, Map<C, V>> rowEntry : map.entrySet()) {
            R row = rowEntry.getKey() ;
            for (Map.Entry<C, V> columnEntry : rowEntry.getValue().entrySet()) {
                C column = columnEntry.getKey() ;
                V value = columnEntry.getValue() ;

                Map<R, V> columnsMap = reverseMap.get(column) ;
                if (columnsMap == null) {
                    columnsMap = new HashMap() ;
                    reverseMap.put(column, columnsMap) ;
                }

                columnsMap.put(row, value) ;
            }
        }

        return reverseMap ;
    }
}