单击时填充微调器

Question

我正在尝试这个简单的程序，我尝试向服务器发送 POST 请求并获取响应并将它们存储到 spinner 中。这是我的代码；

    fetchcolonynames("code");  //sending POST request
    if (spin1 != null) {
        //spin.setAdapter(adapter) doesn't work here
        spin1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
                spin1.setAdapter(adapter); //doesn't work spinner shows nothing on clicked
            }

            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {

            }
        });
    }

这是我的 fetchcolonynames() 方法：

private void fetchcolonynames(String input){
        call=api.fetchcolonynames(input);
        if(call!=null){
            call.enqueue(new Callback<String>() {
                @Override
                public void onResponse(Call<String> call, Response<String> response) {
                    if (response.body() != null) {
                        JSONArray array = null;
                        try {
                            array = new JSONArray(response.body());
                            for(int i=0;i<array.length();i++){
                                arr.add(array.getString(i));
                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                        Collections.sort(arr); //data is correct here
                        adapter = new ArrayAdapter<String>(view.getContext(), android.R.layout.simple_spinner_item,arr);
                        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                        
                    }
                }

                @Override
                public void onFailure(Call<String> call, Throwable t) {

                }
            });
        }
    }

我的所有变量都是全局声明的。我想在用户单击时填充spinner。我该如何实现这个目标？