guava misc

GuavaMisc.java

package sandbox;

import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;

import com.google.common.base.Joiner;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Ordering;

/**
 * GuavaMisc
 * 
 * @author monzou
 */
public class GuavaMisc {

    public static void main(String[] args) {

        // Joiner
        {
            Map<Integer, String> map = Maps.newLinkedHashMap();
            map.put(1, "foo");
            map.put(2, "bar");
            map.put(3, null);
            System.out.println(Joiner.on("&").useForNull("null").withKeyValueSeparator("=").join(map)); // 1=foo&2=bar&3=null
        }

        // Ordering
        {

            List<ValueModel<Integer>> values = Lists.newArrayList();
            values.add(new ValueModel<Integer>(2));
            values.add(new ValueModel<Integer>(3));
            values.add(new ValueModel<Integer>(null));
            values.add(new ValueModel<Integer>(1));
            values.add(null);

            System.out.println(Joiner.on(", ").useForNull("null").join(values)); // 2, 3, null-value, 1, null

            Comparator<ValueModel<Integer>> comparator = Ordering.from(new Comparator<ValueModel<Integer>>() {

                final Comparator<Integer> valueComparator = Ordering.natural().nullsFirst();

                /** {@inheritDoc} */
                @Override
                public int compare(ValueModel<Integer> o1, ValueModel<Integer> o2) {
                    return valueComparator.compare(o1.value, o2.value);
                }
            }).nullsFirst();

            Collections.sort(values, comparator);
            System.out.println(Joiner.on(", ").useForNull("null").join(values)); // null, null-value, 1, 2, 3

        }

    }

    private static class ValueModel<T> {

        T value;

        ValueModel(T value) {
            this.value = value;
        }

        /** {@inheritDoc} */
        @Override
        public String toString() {
            return value == null ? "null-value" : value.toString();
        }

    }

}