List<Map>遍历修改map值

叁歲伎倆 2022-04-11 03:24 509阅读 0赞

有个小需求：

list2 覆盖 list1 对应的值， 无对应时默认list的值，（list1.size()大于list2，只是counts 值不同）  
        list1 \[\{levels=1, counts=0\}, \{levels=2, counts=0\}, \{levels=3, counts=0\}\]  
        list2 \[\{levels=1, counts=2\}, \{levels=3, counts=12\}\]  
        结果： list1 \[\{levels=1, counts=2\}, \{levels=2, counts=0\}, \{levels=3, counts=12\}\]

@Test
    	public void test2() {
    		//模拟数据
    		List<Map<String, Object>> historyList = new ArrayList<Map<String,Object>>();
    		for(int i = 0; i < 3; i++) {
    			Map<String, Object> tempMap = new HashMap<>();
    			tempMap.put("levels", String.valueOf(i+1));
    			tempMap.put("counts", "0");
    			historyList.add(tempMap);
    		}
    		System.out.println("historyList: "+ historyList.toString()); 
    		
    		List<Map<String, Object>> tempList = new ArrayList<Map<String,Object>>();
    		for(int i = 0; i < 2; i++) {
    			Map<String, Object> tempMap = new HashMap<>();
    			tempMap.put("levels", String.valueOf(i+1));
    			tempMap.put("counts", i+5);
    			tempList.add(tempMap);
    		}
    		//修改值
    		if(tempList.size() > 0) {
    			for (Map<String, Object> map : historyList) {
    				String key = String.valueOf(map.get("levels"));
    				String value = String.valueOf(map.get("counts"));
    				for (Map<String, Object> tempmap : tempList) {
    					String tempkey = String.valueOf(tempmap.get("levels"));
    					String tempvalue = String.valueOf(tempmap.get("counts"));
    					if(tempkey.equals(key)) {
    						value = tempvalue;
    						break;
    					}
    				}
    				map.put("counts", value);
    			}
    			int upcount = 0;
    			for (Map<String, Object> map : tempList) {
    				upcount += Integer.parseInt(String.valueOf(map.get("counts")));
    			}
    			System.out.println(upcount);
    		}
    		System.out.println("tempList: "+ tempList.toString()); 
    		System.out.println("historyList: "+ historyList.toString()); 
    	}

结果：

![20181204160523662.png][]

[20181204160523662.png]: /images/20220411/996477ab299048f19566ccbabc5d7806.png