java lambda表达式List＜Bean＞转Map＜String,List＜Bean＞＞或转Map＜String,Bean＞

java lambda表达式List＜Bean＞转Map＜String,List＜Bean＞＞或转Map＜String,Bean＞
以及转Map的key的拼接
先上方法

Map<String, List<ChainAddress>> sysAddressMap = sysAddressList.stream()
                .collect(Collectors.groupingBy(ChainAddress::getChain,
                        HashMap::new, Collectors.toList()));
System.out.println(JSONUtil.toJsonStr(sysAddressMap));
System.out.println("--------");
//可拼接key
Map<String, List<ChainAddress>> sysAddressMap2 = sysAddressList.stream()
        .collect(Collectors.groupingBy(k -> k.getChain() + "-" + k.getType(), HashMap::new,
                Collectors.toList()));
System.out.println(JSONUtil.toJsonStr(sysAddressMap2));

System.out.println("--------");
Map<String, ChainAddress> sysAddressMap3 =
        sysAddressList.stream().collect(
                Collectors.toMap(k -> k.getChain() + "-" + k.getId(), v->v));

完整代码如下：

public class Test {
    public static void main(String[] args) throws Exception {
        List<ChainAddress> sysAddressList = new ArrayList<>();
        ChainAddress address = new ChainAddress();
        address.setId(1L);
        address.setChain("AR");
        address.setAddress("a1");
        address.setType(2);
        sysAddressList.add(address);
        address = new ChainAddress();
        address.setId(2L);
        address.setChain("AR");
        address.setAddress("a2");
        address.setType(2);
        sysAddressList.add(address);
        address = new ChainAddress();
        address.setId(3L);
        address.setChain("AR");
        address.setAddress("b1");
        address.setType(3);
        sysAddressList.add(address);
        address = new ChainAddress();
        address.setId(4L);
        address.setChain("AR");
        address.setAddress("c1");
        address.setType(3);
        sysAddressList.add(address);
        address = new ChainAddress();
        address.setId(5L);
        address.setChain("EC");
        address.setAddress("x1");
        address.setType(2);
        sysAddressList.add(address);
        address = new ChainAddress();
        address.setId(6L);
        address.setChain("EC");
        address.setAddress("x2");
        address.setType(2);
        sysAddressList.add(address);
        address = new ChainAddress();
        address.setId(7L);
        address.setChain("EC");
        address.setAddress("y1");
        address.setType(20);
        sysAddressList.add(address);
        Map<String, List<ChainAddress>> sysAddressMap = sysAddressList.stream()
                .collect(Collectors.groupingBy(ChainAddress::getChain,
                        HashMap::new, Collectors.toList()));
        System.out.println(JSONUtil.toJsonStr(sysAddressMap));
        System.out.println("--------");
        Map<String, List<ChainAddress>> sysAddressMap2 = sysAddressList.stream()
                .collect(Collectors.groupingBy(k -> k.getChain() + "-" + k.getType(), HashMap::new,
                        Collectors.toList()));
        System.out.println(JSONUtil.toJsonStr(sysAddressMap2));
        System.out.println("--------");
        Map<String, ChainAddress> sysAddressMap3 =
                sysAddressList.stream().collect(
                        Collectors.toMap(k -> k.getChain() + "-" + k.getId(), v -> v));
        System.out.println(JSONUtil.toJsonStr(sysAddressMap3));
    }
}

结果集

{“AR”:[{“chain”:“AR”,“address”:“a1”,“type”:2,“id”:1},{“chain”:“AR”,“address”:“a2”,“type”:2,“id”:2},{“chain”:“AR”,“address”:“b1”,“type”:3,“id”:3},{“chain”:“AR”,“address”:“c1”,“type”:3,“id”:4}],“EC”:[{“chain”:“EC”,“address”:“x1”,“type”:2,“id”:5},{“chain”:“EC”,“address”:“x2”,“type”:2,“id”:6},{“chain”:“EC”,“address”:“y1”,“type”:20,“id”:7}]}

{“EC-2”:[{“chain”:“EC”,“address”:“x1”,“type”:2,“id”:5},{“chain”:“EC”,“address”:“x2”,“type”:2,“id”:6}],“EC-20”:[{“chain”:“EC”,“address”:“y1”,“type”:20,“id”:7}],“AR-2”:[{“chain”:“AR”,“address”:“a1”,“type”:2,“id”:1},{“chain”:“AR”,“address”:“a2”,“type”:2,“id”:2}],“AR-3”:[{“chain”:“AR”,“address”:“b1”,“type”:3,“id”:3},{“chain”:“AR”,“address”:“c1”,“type”:3,“id”:4}]}

{“EC-5”:{“chain”:“EC”,“address”:“x1”,“type”:2,“id”:5},“AR-4”:{“chain”:“AR”,“address”:“c1”,“type”:3,“id”:4},“EC-6”:{“chain”:“EC”,“address”:“x2”,“type”:2,“id”:6},“EC-7”:{“chain”:“EC”,“address”:“y1”,“type”:20,“id”:7},“AR-2”:{“chain”:“AR”,“address”:“a2”,“type”:2,“id”:2},“AR-3”:{“chain”:“AR”,“address”:“b1”,“type”:3,“id”:3},“AR-1”:{“chain”:“AR”,“address”:“a1”,“type”:2,“id”:1}}