Java 函数类函数未返回到调用函数的控制器类

我正在从控制器类调用一个函数。函数在另一个类函数中定义。但在执行返回代码之前，它会给出错误。（作为调试）它从modelMap.put（“list”，arraylist）行跳转它给出异常，nullpointerexception

controller.java

@RequestMapping(value = "/index.htm")
    public String getData() throws ClassNotFoundException {
        function obj = new function();
        ModelMap modelMap = null;
        obj.getdata(modelMap);
        return "index";
    }

public ModelMap getdata(ModelMap modelMap) throws ClassNotFoundException {
        SqlRowSet srs = null;
        ArrayList arraylist = new ArrayList();
        SimpleDriverDataSource dataSource = new SimpleDriverDataSource();
        dataSource = new connection.connection().getConnection(dataSource);
        JdbcTemplate get = new JdbcTemplate(dataSource);
        //Operation
        String sql = "SELECT * FROM user_info";
        srs = get.queryForRowSet(sql);
        while (srs.next()) {
            pojo obj = new pojo();
            obj.setEmail_id(srs.getString("email_id"));
            obj.setPassword(srs.getString("pwd"));
            arraylist.add(obj);
        }

        modelMap.put("list", arraylist);
        return modelMap;
    }

function.java

@RequestMapping(value = "/index.htm")
    public String getData() throws ClassNotFoundException {
        function obj = new function();
        ModelMap modelMap = null;
        obj.getdata(modelMap);
        return "index";
    }

public ModelMap getdata(ModelMap modelMap) throws ClassNotFoundException {
        SqlRowSet srs = null;
        ArrayList arraylist = new ArrayList();
        SimpleDriverDataSource dataSource = new SimpleDriverDataSource();
        dataSource = new connection.connection().getConnection(dataSource);
        JdbcTemplate get = new JdbcTemplate(dataSource);
        //Operation
        String sql = "SELECT * FROM user_info";
        srs = get.queryForRowSet(sql);
        while (srs.next()) {
            pojo obj = new pojo();
            obj.setEmail_id(srs.getString("email_id"));
            obj.setPassword(srs.getString("pwd"));
            arraylist.add(obj);
        }

        modelMap.put("list", arraylist);
        return modelMap;
    }

---

modelMap

为

null

，这就是为什么会出现

NullPointerException

。你需要初始化它

ModelMap modelMap = new ModelMap();
obj.getdata(modelMap);

---

谢谢。。它回来了……）但新问题是，返回控制器obj后为空。尽管modelMap有数据。@SurajRoy，但您发布的代码中没有任何内容会使

obj

null

。此外，如果

obj

为

null

，则无法

obj.getdata（modelMap）

（我假设您的意思是

obj

来自

function obj=new function（）；

）。