java 动态树与递归平整

Posted 2021-05-08

import org.junit.Test;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.*;

public class DynamicTreeTest {

    @Test
    public void testDynamicTree() throws Exception {

        // given
        DynamicTree<Customer> tree = new DynamicTree<Customer>(
                new Customer("Manager"),
                new DynamicTree(new Customer("Cashier-001"),
                        new DynamicTree(new Customer("Cashier-010"),
                                new DynamicTree(new Customer("Cashier-100")),
                                new DynamicTree(new Customer("Cashier-101")),
                                new DynamicTree(new Customer("Cashier-102"))),
                        new DynamicTree(new Customer("Cashier-011"),
                                new DynamicTree(new Customer("Cashier-110")),
                                new DynamicTree(new Customer("Cashier-111")),
                                new DynamicTree(new Customer("Cashier-112"))),
                        new DynamicTree(new Customer("Cashier-012"),
                                new DynamicTree(new Customer("Cashier-120")),
                                new DynamicTree(new Customer("Cashier-121")),
                                new DynamicTree(new Customer("Cashier-122")))),
                new DynamicTree(new Customer("Cashier-002"),
                        new DynamicTree(new Customer("Cashier-020"),
                                new DynamicTree(new Customer("Cashier-200")),
                                new DynamicTree(new Customer("Cashier-201")),
                                new DynamicTree(new Customer("Cashier-202"))),
                        new DynamicTree(new Customer("Cashier-021"),
                                new DynamicTree(new Customer("Cashier-210")),
                                new DynamicTree(new Customer("Cashier-211")),
                                new DynamicTree(new Customer("Cashier-212"))),
                        new DynamicTree(new Customer("Cashier-022"),
                                new DynamicTree(new Customer("Cashier-220")),
                                new DynamicTree(new Customer("Cashier-221")),
                                new DynamicTree(new Customer("Cashier-222")))),
                new DynamicTree(new Customer("Cashier-003"),
                        new DynamicTree(new Customer("Cashier-030"),
                                new DynamicTree(new Customer("Cashier-300")),
                                new DynamicTree(new Customer("Cashier-301")),
                                new DynamicTree(new Customer("Cashier-302"))),
                        new DynamicTree(new Customer("Cashier-031"),
                                new DynamicTree(new Customer("Cashier-310")),
                                new DynamicTree(new Customer("Cashier-311")),
                                new DynamicTree(new Customer("Cashier-312"))),
                        new DynamicTree(new Customer("Cashier-032"),
                                new DynamicTree(new Customer("Cashier-320")),
                                new DynamicTree(new Customer("Cashier-321")),
                                new DynamicTree(new Customer("Cashier-322")))),
                new DynamicTree(new Customer("Cashier-004"),
                        new DynamicTree(new Customer("Cashier-040"),
                                new DynamicTree(new Customer("Cashier-400")),
                                new DynamicTree(new Customer("Cashier-401")),
                                new DynamicTree(new Customer("Cashier-402"))),
                        new DynamicTree(new Customer("Cashier-041"),
                                new DynamicTree(new Customer("Cashier-410")),
                                new DynamicTree(new Customer("Cashier-411")),
                                new DynamicTree(new Customer("Cashier-412"))),
                        new DynamicTree(new Customer("Cashier-042"),
                                new DynamicTree(new Customer("Cashier-420")),
                                new DynamicTree(new Customer("Cashier-421")),
                                new DynamicTree(new Customer("Cashier-422"))))
        );

        // when
        List<Customer> customers = tree.flattened()
                .map(c -> c.getValue())
                .sorted(new Comparator<Customer>() {
                    @Override
                    public int compare(Customer c1, Customer c2) {
                        return c1.getName().compareTo(c2.getName());
                    }
                })
                .collect(Collectors.toList());

        // then

        // customers.forEach(c -> System.out.println("Customer Name = " + c.getName()));
        assertThat(customers.size(), is(53));
    }
}

import java.util.Arrays;
import java.util.List;
import java.util.stream.Stream;

public class DynamicTree<T> {
    private T value;
    private List<DynamicTree<T>> dynamicTrees;

    public DynamicTree(T value, List<DynamicTree<T>> dynamicTrees) {
        this.value = value;
        this.dynamicTrees = dynamicTrees;
    }

    public DynamicTree(T value, DynamicTree<T>... dynamicTrees) {
        this.value = value;
        this.dynamicTrees = Arrays.asList(dynamicTrees);
    }

    public T getValue() {
        return value;
    }

    public void setValue(T value) {
        this.value = value;
    }

    public List<DynamicTree<T>> getDynamicTrees() {
        return dynamicTrees;
    }

    public void setDynamicTrees(List<DynamicTree<T>> dynamicTrees) {
        this.dynamicTrees = dynamicTrees;
    }

    public Stream<DynamicTree<T>> flattened() {
        return Stream.concat(
                Stream.of(this),
                dynamicTrees.stream().flatMap(DynamicTree::flattened));
    }
}