异步GET请求方法接收数据，但返回空数组，在调试时工作正常

Question

MainActivity.java

String[] captcha = new String[2];

b.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            getMessle();
        }
    });

private void getMessle() {
    captcha[0] = "before";
    captcha[1] = "before2";

    RequestClass rc = new RequestClass();
    captcha = rc.getCaptcha();
    tv.setText(captcha[1]);

}

RequestClass.java

String[] saResult = new String[2];

public String[] getCaptcha() {

    httpUrl = new HttpUrl.Builder()
            .scheme(strScheme)
            .host(strHost)
            .addPathSegments(path)
            .build();

    request = new Request.Builder()
            .url(httpUrl)
            .addHeader(header, key)
            .build();

    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {

        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            saResult[0] = response.header("Set-Cookie");
            try {
                jsonObject = new JSONObject(response.body().string());
                saResult[1] = jsonObject.getString("image_url");
            } catch (JSONException je) {

            }
        }
    });
    return saResult;
}

I've checked and it doesn't seem like any exceptions are caught. I also know that my application gets a response as well and the datas are definitely there in onResponse(). After some extended testing, it looks like my array is assigned before the response arrives.

Answer 1

captcha = rc.getCaptcha();

You call that right after you enqued a request. The request is not executed then nor is there a result. All goes asynchronous.

Only in onResponse() you will get the result. A long time later. And it is in onResponse() that you should handle the result by displaying it in a text view for instance.