//原始数据源
List<Map<String, Object>> data = new ArrayList<Map<String, Object>>();

//要添加的数据源 这个新的数据源是从数据库中查询出来的。暂定执行5次也就是要向data 中添加5次
List<Map<String, Object>> newData = new ArrayList<Map<String, Object>>();

//最终的组合是这样的一个效果 List<Map<String, Object>> data  
   key ="博士",value="12";
   key ="研究生",value="13";
   key ="本科",value="3";

newData ==》添加到data 中 如果key相同的话那就value相加，如果在data 中不存在相应的key 则新put一个数据到里面
比如newData 

   key ="博士",value="3";
   key ="研究生",value="3";
   key ="本科",value="3";
   key ="专科",value="13";
那前三项的key都能在data中找到则value相加，key="专科"在data中找不到则添加这个map到data list 中去。

List<Map<String, Object>> data = new ArrayList<Map<String, Object>>();
List<Map<String, Object>> newData = new ArrayList<Map<String, Object>>();

for(Map newMap : newData) {
    Iterator<String> it = newMap.keySet().iterator();

    while(it.hasNext()) {
        String key = it.next();
        boolean find = false;

        for(Map map : data) {
           if(map.containsKey(key)) {
               find = true;
               map.put(key, 
                   String.valueOf(
                      Integer.parse(map.get(key)) + Integer.parse(newMap.get(key))));
               break;
           }
        }

        if(!find) {
           map.put(key, String.valueOf(Integer.parse(newMap.get(key))));
        }
    }
}

------解决方案--------------------

Java code

package test;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class MapTest {

    public static void main(String []args){
        Map<String,Integer> data = new HashMap<String,Integer>();
        data.put("博士", 12);
        data.put("研究生", 13);
        data.put("本科", 3);
        
        Map<String,Integer> newData = new HashMap<String,Integer>();
        newData.put("博士", 3);
        newData.put("研究生", 3);
        newData.put("本科", 3);
        newData.put("专科", 13);
        
        Iterator<String> it = newData.keySet().iterator();
        while(it.hasNext()){
            String s = it.next();
            Integer val = data.get(s);
            if(val==null){
                data.put(s, newData.get(s));
            }else{
                data.put(s, val+newData.get(s));
            }
        }
        Iterator<String> t = data.keySet().iterator();
        while(t.hasNext()){
            String temp = t.next();
            System.out.println(temp+":"+data.get(temp));
        }
    }
}

------解决方案--------------------

for example
Java code
import java.util.*;
public class Test {
    public static void main(String []args){
        List<Map<String, Object>> data = new ArrayList<Map<String, Object>>();
        List<Map<String, Object>> newData = new ArrayList<Map<String, Object>>();
        //sample original data
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("博士", "12");
        data.add(map);
        map = new HashMap<String, Object>();
        map.put("研究生", "13");
        data.add(map);
        map = new HashMap<String, Object>();
        map.put("本科", 3);
        data.add(map);
        //sample new data
        map = new HashMap<String, Object>();
        map.put("博士", "3");
        newData.add(map);
        map = new HashMap<String, Object>();
        map.put("研究生", "3");
        newData.add(map);
        map = new HashMap<String, Object>();
        map.put("本科", "3");
        newData.add(map);
        map = new HashMap<String, Object>();
        map.put("专科", "13");
        newData.add(map);
        //merge
        List<Map<String, Object>> addData = new ArrayList<Map<String, Object>>();
        for (Map<String, Object> m1 : newData) {
            for (Map.Entry<String, Object> e1 : m1.entrySet()) {
                boolean exist = false;
                for (Map<String, Object> m2 : data) {
                    if (m2.containsKey(e1.getKey())) {
                        exist = true;
                        m2.put(e1.getKey(), 
                            Integer.valueOf((String)m2.get(e1.getKey())) + 
                            Integer.valueOf((String)e.getValue()));
                        break;
                    }
                }
                if (! exist) {
                    map = new Map<String, Object>();
                    map.put(e1.getKey(), e1.getValue());
                    addData.add(map);
                }
            }
        }
        data.addAll(addData);
    }
}