Question

打招呼，我很难在ValueEventListener中为变量设置int值，并在ValueEventListener之外获取要检查的方法的值为value == 1，该方法将为return 1，否则返回0

我已经尝试了多种方法，例如通过SharedPreferences保存值，将值设置为Textview并从textview调用，但是方法仍然总是return 0，因为它无法读取在ValueEventListener中设置的值。任何帮助都非常感谢。谢谢

这里是我的代码

int status = 0;
protected void onCreate(Bundle savedInstanceState) {
    ...

    btnSync_in.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if (getCustomerList() == 1) {
                msg = msg + "Get customer success \n";
            } else {
                msg = msg + "Get customer unsuccessful \n";
            }

            AlertDialog.Builder statusDialog = new AlertDialog.Builder(SyncActivity.this);
            statusDialog.setPositiveButton("OK", null);
            statusDialog.setTitle("Status");
            statusDialog.setMessage(msg);
            statusDialog.show();
            msg = "";
        }
    });
}

将返回int的方法

private int getCustomerList() {
    urlRef = myRef.child("...");
    urlRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            ...

            StringRequest stringRequest = new StringRequest(Request.Method.GET, customerURL, new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    status = 1; //here my problem, value assign here is success

                    try {
                        ...
                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    ...
                    status = 0; // here if unsuccessful

                }
            });
            RequestQueue requestQueue = Volley.newRequestQueue(SyncActivity.this);
            requestQueue.add(stringRequest);
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
            ...
        }
    });

    if (status == 1) {
        return 1;
    } else {
        return 0;
    }
}

Answer 1

一种更好的方式为什么不在 AlertDialog 方法中显示getCustomerList()

像这样呼叫您的getCustomerList()

btnSync_in.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            getCustomerList();

        }
    });

然后将您的 AlertDialog 这样添加到getCustomerList()内

示例代码

 private void getCustomerList() {


    AlertDialog.Builder statusDialog = new AlertDialog.Builder(SyncActivity.this);
    statusDialog.setPositiveButton("OK", null);
    statusDialog.setTitle("Status");

    urlRef = myRef.child("...");
    urlRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            ...

            StringRequest stringRequest = new StringRequest(Request.Method.GET, customerURL, new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    msg = msg + "Get customer success \n";

                     statusDialog.setMessage(msg);
                     statusDialog.show();
                     msg = "";


                    try {
                        ...
                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    ...
                    msg = msg + "Get customer unsuccessful \n";
                    statusDialog.setMessage(msg);
                    statusDialog.show();
                    msg = "";

                }
            });
            RequestQueue requestQueue = Volley.newRequestQueue(SyncActivity.this);
            requestQueue.add(stringRequest);
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
            ...
        }
    });


}

方法int返回错误值

1 个答案: