关于Java函数式编程

[nnnnyyyy]

用java读取Neo4j数据库。返回一个org.neo4j.driver.Result类型。需要转化为List<WechatDepartment>。发现里面有<T> List<T> list(Function<Record, T> var1)，这种函数式编程，请问应该怎么以调用?

public Result selectChild(Long departmentId) {

        try {
            Map<String, Object> paramentMap = Collections.singletonMap("departmentId", departmentId);

            String sqlText = "MATCH(N:WechatDepartment)-[:child]->(M:WechatDepartment) \n" +
                    "WHERE N.departmentId = {departmentId} \n" +
                    "RETURN ID(M) as id, M.departmentId as departmentId, M.name as name, M.order as order, M.enable as enable";

	    //返回一个org.neo4j.driver.Result类型
            Result result = session.run(sqlText, paramentMap);

	    //需要转化为List<WechatDepartment>

	    //方法1 List<Record> list();
	    List<Record> records = result.list();

           //方法2 <T> List<T> list(Function<Record, T> var1)  
	   ???  
	

            return result;
        } catch (Exception e) {
            System.out.println(e);
            throw e;
        } finally {
            //session.close();
        }
    }

public interface Result extends Iterator<Record> {
    List<String> keys();

    boolean hasNext();

    Record next();

    Record single() throws NoSuchRecordException;

    Record peek();

    Stream<Record> stream();

    List<Record> list();

    <T> List<T> list(Function<Record, T> var1);

    ResultSummary consume();
}

[sotondolphin]

你可以定义一个 Function 的对象，然后传入到那个list 方法 Function<Record, WechatDepartment> getWechatDepartmenList = record -> { return 从record 里面抽出WechatDepartment的逻辑； // 比如 WechatDepartment department = new WechatDepartment(); department.setName(record.getName) department.setCode(record.getDeptCode); return department; } List<WechatDepartment> departments = result.list(getWechatDepartment);

[nnnnyyyy]

引用 1 楼 sotondolphin 的回复:

你可以定义一个 Function 的对象，然后传入到那个list 方法 Function<Record, WechatDepartment> getWechatDepartmenList = record -> { return 从record 里面抽出WechatDepartment的逻辑； // 比如 WechatDepartment department = new WechatDepartment(); department.setName(record.getName) department.setCode(record.getDeptCode); return department; } List<WechatDepartment> departments = result.list(getWechatDepartment);

首先感谢您的回复，我封装了上面的方法，发现并没有调用到，请问是什么原因？

public class RecordToBean {

    public static Function<Record, WechatDepartment> recordToWechatDepartment = record -> {

//这里没有打印
        System.out.println("===================:" + record.get("name").asString());

        WechatDepartment wechatDepartment = new WechatDepartment();

        wechatDepartment.setDepartmentId(record.get("departmentId").asLong());
        wechatDepartment.setName(record.get("name").asString());
        wechatDepartment.setParentId(record.get("parentId").asLong());
        wechatDepartment.setOrder(record.get("order").asLong());
        wechatDepartment.setEnable(record.get("enable").asInt());

        return wechatDepartment;
    };
}

            //方法2
            List<WechatDepartment> departments = result.list(RecordToBean.recordToWechatDepartment);
//长度为0
            System.out.println("departments.size():" + departments.size());

[长江水面写日记]

result是个接口,在实现类里面写调用函数的逻辑才真的调用啊

     @Override
			public <T> List<T> list(Function<String, T> var1) {
				List<String> list = this.list();
				return list.stream().map(var1::apply).collect(Collectors.toList());
			}