package com.baifan.collecting;

import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.sql.SQLOutput;
import java.util.Arrays;
import java.util.IntSummaryStatistics;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.TreeSet;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * @author: baifan
 * @date: 2021/2/5
 */
public class CollectingTest {

    public static void main(String[] args) throws Exception {
        Iterator<Integer> iterator = Stream.iterate(0, n -> n + 1).limit(10).iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }

        Object[] numbers = Stream.iterate(0, n -> n + 1).limit(10).toArray();
        System.out.println("Object array:" + numbers);

        try {
            Integer number = (Integer) numbers[0];
            System.out.println("number:" + number);
            System.out.println("The following statement throws an exception:");
            Integer[] numbers2 = (Integer[]) numbers;
        } catch (Exception e) {
            System.out.println(e);
        }

        Integer[] numbers3 = Stream.iterate(0, n -> n + 1).limit(10).toArray(Integer[]::new);
        System.out.println("Integer array:" + numbers3);

        Set<String> wordset = fileSplitsStream().collect(Collectors.toSet());
        show("wordset", wordset);

        TreeSet<String> wordsTreeSet = fileSplitsStream().collect(Collectors.toCollection(TreeSet::new));
        show("wordsTreeSet", wordsTreeSet);

        String jionResult = fileSplitsStream().limit(10).collect(Collectors.joining());
        System.out.println("jionResult:" + jionResult);

        String jionResult2 = fileSplitsStream().limit(10).collect(Collectors.joining(", "));
        System.out.println("Jion with commas:" + jionResult2);

        //这个很强大用来统计超级好!!!!
        IntSummaryStatistics summary = fileSplitsStream().collect(Collectors.summarizingInt(String::length));
        double averageWordLength = summary.getAverage();
        double maxWordLength = summary.getMax();
        System.out.println("Average word length:" + averageWordLength);
        System.out.println("Max word length:" + maxWordLength);
        System.out.println("forEach:");
        fileSplitsStream().limit(10).forEach(System.out::println);
    }

    public static Stream<String> fileSplitsStream() throws Exception {
        String contents = new String(Files.readAllBytes(Paths.get("D:/sql/java库.sql")), StandardCharsets.UTF_8);
        List<String> wordList = Arrays.asList(contents.split("\\PL+"));
        Stream<String> words = wordList.stream();
        return words.map(s -> s.replaceAll("\\*", "1"));
    }

    public static <T> void show(String label, Set<T> set) {
        System.out.println(label + ":" + set.getClass().getName());
        System.out.println("[" + set.stream().limit(10).map(Objects::toString).collect(Collectors.joining(", ")) + "]");
    }
}