将方法移动到另一个 Java 类，并从原始类中调用该方法

Question

Dear valued program gurus!

I need help on moving a method to another Java class.

I am having a Java class called ProfileList.java containing the following code:

package dk.timeleft.versionone;

import androidx.appcompat.app.AppCompatActivity;

import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class ProfileList extends AppCompatActivity {

    Button btnGet;
    Button btnPost;
    TextView txtResult;

    public String url;
    public String postUrl;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_profile_list);

        btnGet = (Button) findViewById(R.id.btnGet);
        btnPost = (Button) findViewById(R.id.btnPost);
        txtResult = (TextView) findViewById(R.id.txtResult);


        btnGet.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                txtResult.setText("Retrieving GET-data");
                url = "https://kairosplanner.com/api/timeleft.php";
                try {
                    getResponse();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });

        btnPost.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                txtResult.setText("Retrieving POST-data");

                postUrl = "https://kairosplanner.com/api/timeleft2.php/";
                RequestBody postBody = new FormBody.Builder()
                        .add("first_name", "Hans")
                        .add("last_name", "Schmidt")
                        .build();
                try {
                    postRequest(postUrl, postBody);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });

    }

    void postRequest(String postUrl, RequestBody postBody) throws IOException {

        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url(postUrl)
                .post(postBody)
                .build();

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

            @Override
            public void onResponse(Call call, Response response) throws IOException {

                final String myResponse = response.body().string();

                ProfileList.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            JSONObject json = new JSONObject(myResponse);
                            //txtString.setText("First Name: "+json.getJSONObject("data").getString("first_name") + "\nLast Name: " + json.getJSONObject("data").getString("last_name"));
                            txtResult.setText(json.toString());
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });

            }
        });
    }


    void getResponse() throws IOException {

        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url(url)
                .build();

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

            @Override
            public void onResponse(Call call, Response response) throws IOException {

                final String myResponse = response.body().string();

                ProfileList.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        try {

                            JSONObject json = new JSONObject(myResponse);
                            //txtString.setText("First Name: "+json.getJSONObject("data").getString("first_name") + "\nLast Name: " + json.getJSONObject("data").getString("last_name"));
                            txtResult.setText(json.toString());
                            Toast.makeText(ProfileList.this,"Hello",Toast.LENGTH_SHORT).show();

                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });

            }
        });
    }

    public class OkHttpHandler extends AsyncTask<String, Void, String> {

        OkHttpClient client = new OkHttpClient();

        @Override
        protected String doInBackground(String... params) {

            Request.Builder builder = new Request.Builder();
            builder.url(params[0]);
            Request request = builder.build();

            try {
                Response response = client.newCall(request).execute();
                return response.body().string();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            //txtString.setText(s);
        }
    }

}

This is working without any problems, but I'd like to have my code clean an neat. I will be using the POST and GET functions (postRequest and getResponse methods) often, also in other Java classes, so it would be better, I guess, if those methods, including the OkHttpHandler class, to a separate Java class, eg ApiCommunicator.java, and call the methods from there.

I found a lot of information on how to refactor, but that just deletes the current ProfileList.java class.

I also tried just to copy the methods (postRequest, getResponse and OkHttpHandler to ApiCommunicator.java (and afterwards delete these methods from ProfileList.java), but that gives a few other problems, eg the .runOnUiThread runnable within the OnResponse method in postRequest and getResponse - those refer to ProfileList.this in stead of a dynamic Java class.

So my question is: how do I move a method from one class to another, and call the method from the original class?

BTW: I am using IntelliJ

I hope somebody can help me with this problem.

Answer 1

EDITED: Added ApiCommunicatorListener interface to ApiCommunicator that needs to be implemented by ProfileList activity to get the result back and assign it to txtResult.

You could create your ApiCommunicator class like so:

public class ApiCommunicator<T extends AppCompatActivity & ApiCommunicator.ApiCommunicatorListener> {

    private T activity;

    public ApiCommunicator(T activity) {
        this.activity = activity;
    }

    public void postRequest(String postUrl, RequestBody postBody) throws IOException {

        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url(postUrl)
                .post(postBody)
                .build();

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

            @Override
            public void onResponse(Call call, Response response) throws IOException {

                final String myResponse = response.body().string();

                activity.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            JSONObject json = new JSONObject(myResponse);
                            activity.postRequestResult(json.toString());
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });

            }
        });
    }

    public void getResponse() throws IOException {

        OkHttpClient client = new OkHttpClient();

        Request request = new Request.Builder()
                .url(url)
                .build();

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

            @Override
            public void onResponse(Call call, Response response) throws IOException {

                final String myResponse = response.body().string();

                activity.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            JSONObject json = new JSONObject(myResponse);
                            activity.getResponseResult(json.toString());
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }
                });

            }
        });
    }

    public interface ApiCommunicatorListener {
        void postRequestResult(String result);
        void getResponseResult(String result);
    }
}

After that, you need to implement the interface in ProfileList activity like so:

public class ProfileList extends AppCompatActivity implements ApiCommunicator.ApiCommunicatorListener {

Then you're gonna add those two methods to ProfileList:

@Override
public void postRequestResult(String result) {
    txtResult.setText(result);
}

@Override
public void getResponseResult(String result) {
    txtResult.setText(result);
}

And finally use ApiCommunicator:

ApiCommunicator apiCommunicator = new ApiCommunicator<>(this);
apiCommunicator.postRequest(...);
apiCommunicator.getRequest(...);