Lambda表达式map分组 - map排序工具

package com.mingjia.data_control.test;

import com.mingjia.data_control.ZDCApplication;
import com.mingjia.data_control.modules.product_module.entity.Product;
import org.springframework.boot.SpringApplication;

import java.time.LocalDate;
import java.util.*;
import java.util.stream.Collectors;

public class Tast {

    public static void main(String[] args) {

        Product product = new Product();
        product.setViewCount(1);
        product.setTitle("商品1");

        Product product2 = new Product();
        product2.setViewCount(10);
        product2.setTitle("商品3");

        Product product3 = new Product();
        product3.setViewCount(3);
        product3.setTitle("商品2");

        Product product4 = new Product();
        product4.setViewCount(11);
        product4.setTitle("商品2");

        List<Product> products = new ArrayList<>();
        products.add(product);
        products.add(product2);
        products.add(product3);
        products.add(product4);

        //单个字段，分组求和（datas）
        Map<String, Integer> enusersCollect1 =
                products.stream().collect(Collectors.groupingBy(Product:: getTitle, Collectors.summingInt(Product :: getViewCount)));
        System.out.println("-----"+enusersCollect1.get("商品2"));
        
        //排序
        enusersCollect1 =sortByValue(enusersCollect1,0);
		//循环排序后的结果
        for (Map.Entry<String, Integer> entry : enusersCollect1.entrySet()) {
            String key = entry.getKey();
            String value = entry.getValue().toString();
            System.out.println("key=" + key + " value=" + value);
        }
    }

    /**
     * flag = 1 正序
     * flag = 0 倒序
     * @param map
     * @param flag
     * @return
     */
    public static <K, V extends Comparable<? super V>> Map<K, V> sortByValue(Map<K, V> map, int flag) {
        Map<K, V> sortMap = new LinkedHashMap<>();
        if(flag == 1) {
            map.entrySet().stream()
                    .sorted((o1, o2) -> o1.getValue().compareTo(o2.getValue()))
                    .forEach(entry -> sortMap.put(entry.getKey(), entry.getValue()));
        } else {
            map.entrySet().stream()
                    .sorted((o1, o2) -> o2.getValue().compareTo(o1.getValue()))
                    .forEach(entry -> sortMap.put(entry.getKey(), entry.getValue()));
        }
        return sortMap;
    }
}