ru.yandex.bolts.collection.example.MapFExample Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of bolts Show documentation

Collections utilities used in various Yandex projects

The newest version!

package ru.yandex.bolts.collection.example;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import org.junit.Test;

import ru.yandex.bolts.collection.Cf;
import ru.yandex.bolts.collection.MapF;
import ru.yandex.bolts.function.Function1B;


public class MapFExample {

    @Test
    public void getOrElse() {
        MapF map = Cf.map("a", 1, "b", 2);

        // works like "get" when map has specified key
        assertEquals(1, map.getOrElse("a", 44).intValue());

        // otherwise uses default value
        assertEquals(33, map.getOrElse("z", 33).intValue());
    }

    @Test
    public void getOrElseUpdate() {
        MapF map = Cf.hashMap();

        // initialize value by key "a"
        assertEquals(1, map.getOrElseUpdate("a", 1).intValue());
        // works like "get", because map contains requested key
        assertEquals(1, map.getOrElseUpdate("a", 2).intValue());
    }

    @Test
    public void plus() {
        // plus can be used to union maps
        MapF orig = Cf.hashMap();
        assertEquals(Cf.map("a", 1, "b", 2), orig.plus1("a", 1).plus(Cf.map("b", 2)));

        // original collection is still empty, because "plus" operation is functional
        assertTrue(orig.isEmpty());
    }

    @Test
    public void filterKeys() {
        Function1B goodKeyPredicate = Function1B.equalsF("b").notF();
        // map keys may be filtered
        assertEquals(Cf.map("a", 1), Cf.map("a", 1, "b", 2).filterKeys(goodKeyPredicate));
    }

    @Test
    public void mapValues() {
        // mapValues applies function to each value of map
        assertEquals(Cf.map("a", 1, "b", 2), Cf.map("a", "1", "b", "2").mapValues(Cf.Integer.parseF()));
    }

} //~