开发环境：jdk 1.8

需求一：
1、统计每个小时(升序)不同事件的产品产量
2、统计不同事件（OK 、NG）的总产量

public static void main(String[] args) {
		
    	//数据源
        List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();
        Map<String, Object> map1 = new HashMap<String, Object>();
        map1.put("hour", "10");//小时
        map1.put("event", "OK");//事件
        map1.put("number", 12);//产量
        list.add(map1);
        
        Map<String, Object> map2 = new HashMap<String, Object>();
        map2.put("hour", "08");
        map2.put("event", "NG");
        map2.put("number", 10);
        list.add(map2);
        
        Map<String, Object> map3 = new HashMap<String, Object>();
        map3.put("hour", "09");
        map3.put("event", "NG");
        map3.put("number", 7);
        list.add(map3);
        
        Map<String, Object> map4 = new HashMap<String, Object>();
        map4.put("hour", "08");
        map4.put("event", "OK");
        map4.put("number", 30);
        list.add(map4);
        
        System.out.println(list);
        System.out.println("--------------------------");
        
        // 进行分组和汇总 并 按hour字段的升序排序
        // 按小时统计每个小时的事件和数量
        Map<String, Map<String, Integer>> hourEventNumberSum = list.stream()
            .collect(Collectors.groupingBy(
                item -> (String) item.get("hour"),
                TreeMap::new, // 使用 TreeMap 以保证 hour 字段升序
                Collectors.groupingBy(
                    item -> (String) item.get("event"),
                    Collectors.summingInt(item -> (Integer) item.get("number"))
                )
            ));

        // 打印结果
        // 这里如果直接定义int变量累加计算总和，会报错：Local variable count defined in an enclosing scope must be final or effectively final，增强for里面用外部变量需要final，但这里在做累加计算，无法使用final修饰，所以改用了List<Integer>计算总和
        //计算OK总和用的集合
		List<Integer> listOk = new ArrayList<Integer>();
		//计算NG总和用的集合
		List<Integer> listNg = new ArrayList<Integer>();
        hourEventNumberSum.forEach((hour, eventMap) -> {
            System.out.println("Hour: " + hour);
            eventMap.forEach((event, number) -> {
                System.out.println("  Event: " + event + ", Number: " + number);
                if ("OK".equals(event.toUpperCase())) {
					listOk.add(number);
				}else if ("NG".equals(event.toUpperCase())) {
					listNg.add(number);
				}
            });
        });
    	
        System.out.println("--------------------------");
        
        //计算OK总和
        int sumOk = listOk.stream()
                .mapToInt(Integer::intValue) // 转换成 IntStream
                .sum(); // 计算和
        
        System.out.println("OK Sum of elements: " + sumOk);
        
        //计算NG总和
        int sumNg = listNg.stream()
                .mapToInt(Integer::intValue) // 转换成 IntStream
                .sum(); // 计算和

        System.out.println("NG Sum of elements: " + sumNg); 
        
	}

执行结果

需求二：
统计每个小时(倒序)不同事件的产品产量

public static void main29(String[] args) {
    	
    	//数据源
        List<Map<String, Object>> list = new ArrayList<Map<String,Object>>();
        Map<String, Object> map1 = new HashMap<String, Object>();
        map1.put("hour", "10");
        map1.put("event", "B");
        map1.put("number", 12);
        list.add(map1);
        
        Map<String, Object> map2 = new HashMap<String, Object>();
        map2.put("hour", "08");
        map2.put("event", "A");
        map2.put("number", 10);
        list.add(map2);
        
        Map<String, Object> map3 = new HashMap<String, Object>();
        map3.put("hour", "09");
        map3.put("event", "A");
        map3.put("number", 7);
        list.add(map3);
        
        Map<String, Object> map4 = new HashMap<String, Object>();
        map4.put("hour", "08");
        map4.put("event", "B");
        map4.put("number", 30);
        list.add(map4);
    	
		System.out.println(list);
        System.out.println("--------------------------");
        
    	// 进行分组和汇总
        Map<String, Map<String, Integer>> hourEventNumberSum = list.stream()
            .collect(Collectors.groupingBy(
                item -> (String) item.get("hour"),
                TreeMap::new, // 使用 TreeMap 以保证按 hour 字段升序
                Collectors.groupingBy(
                    item -> (String) item.get("event"),
                    Collectors.summingInt(item -> (Integer) item.get("number"))
                )
            ));

        // 将 TreeMap 转换为倒序的 LinkedHashMap
        Map<String, Map<String, Integer>> sortedHourEventNumberSum = hourEventNumberSum.entrySet()
            .stream()
            .sorted(Map.Entry.<String, Map<String, Integer>>comparingByKey(Comparator.reverseOrder()))
            .collect(Collectors.toMap(
                Map.Entry::getKey,
                Map.Entry::getValue,
                (e1, e2) -> e1,
                LinkedHashMap::new
            ));
        
        // 打印结果
        sortedHourEventNumberSum.forEach((hour, eventMap) -> {
            System.out.println("Hour: " + hour);
            eventMap.forEach((event, number) -> {
                System.out.println("  Event: " + event + ", Number: " + number);
            });
        });
	}