Question

public class MainActivity extends AppCompatActivity {

    //    Button senddata;
    //private final String url = "http://19.168.1.58:9090/data/db";

    public static final String KEY_EMAIL = "email";

    EditText email1;
    String emailString;
    String _id, _name, _pass, _email;
    TextView displayjsonText;
    DataRecieveJson dr;
    ArrayList<agentPojo> list;
    agentPojo agentdetails;
    synck sy;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        email1 = (EditText) findViewById(R.id.email);
        displayjsonText = (TextView) findViewById(R.id.displayView);
    }

    public void checkdata(View view){
        emailString= email1.getText().toString();
        dr = new DataRecieveJson(this, emailString);
        dr.RecieveData();
        dr.te();
    }
}

public class DataRecieveJson {

    Context mcontext;
    String jresponse;
    public String _id = "";
    String _name;
    String _pass = "" ;
    String _email = "";

    String mail;
    JSONObject obj;

    ArrayList<agentPojo> list;
    //    ArrayList<agentPojo> nlist;
    agentPojo agent;

    public DataRecieveJson(Context mcontext,String mail) {
        this.mcontext = mcontext;
        this.mail = mail;
    }

    public void RecieveData() {

        RequestQueue queue = Volley.newRequestQueue(mcontext);
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, url.jurl + mail, null, new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            parsejson(response);
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.d("onErrorResponse: ", error.toString());
            Toast.makeText(mcontext, error.toString(), Toast.LENGTH_LONG).show();
        }
    });
        int socketTimeout = 30000;
        RetryPolicy policy = new DefaultRetryPolicy(socketTimeout, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT);
        jsonObjectRequest.setRetryPolicy(policy);
        queue.add(jsonObjectRequest);
    }

    public void parsejson(JSONObject response) {
        list= new ArrayList<agentPojo>();
        agent = new agentPojo();

        try {
            JSONArray ag1 = response.getJSONArray("agentD");
            for (int i = 0; i < ag1.length(); i++) {

                JSONObject ag = ag1.getJSONObject(i);
                // _id = ag.getString("id");
                // _name = ag.getString("name");
                // _pass = ag.getString("password");
                // _email = ag.getString("email");

                agent.setId(ag.getString("id"));
                agent.setName(ag.getString("name"));
                agent.setPass(ag.getString("password"));
                agent.setEmail(ag.getString("email"));

                list.add(agent);

                Log.d("parsejson: ", String.valueOf(list));

                // Log.d("parsejson: ", "Hello");
                agentPojo po;
                String id = null, email = null;
                for (int j = 0; j < list.size() ; j++) {
                    po = list.get(j);

                    id = po.getId();
                    email = po.getEmail();
                }
                Log.d("RecieveDataInside: ", id + "," + email);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
        Log.d("Pj:Id ", String.valueOf(list));
    }

    public void te() {
        Log.d("test:Id ", String.valueOf(list));
    }
}

日志：

09-17 07:24:52.689 21681-21681/com.example.pawar.sendtoservlet D/test:Id: null
09-17 07:24:53.061 21681-21681/com.example.pawar.sendtoservlet D/parsejson:: [com.example.pawar.sendtoservlet.agentPojo@536b7f1c]
09-17 07:24:53.061 21681-21681/com.example.pawar.sendtoservlet D/RecieveDataInside:: 1,ram21@gmail.com
09-17 07:24:53.061 21681-21681/com.example.pawar.sendtoservlet D/Pj:Id: [com.example.pawar.sendtoservlet.agentPojo@536b7f1c]

ArrayList在方法null中显示Te()。

Answer 1

ArrayList尚未初始化到您收到日志消息的位置，这就是ArrayList为null的原因。

在跟踪您的方法后，我发现您只在parsejson()中初始化列表，parsejson()仅在您onResponse()的{{1}}中调用{ {1}}。

这必须意味着new JsonObjectRequest()未被调用，这就是ReceiveData()未运行且onResponse()为parsejson()的原因。

我建议你做一些评论提到的内容，即使用更多日志语句来帮助您调查list未被调用的原因。

Answer 2

尝试全局初始化

ArrayList list = new ArrayList（）;

ArrayList在方法Te（）中显示null

2 个答案: