Generics

genericsproject_CustomCallback.java

package com.lbalmaceda.genericsproject;

import com.lbalmaceda.genericsproject.exceptions.CustomException;

/**
 * Created by lbalmaceda on 6/21/16.
 */
public interface CustomCallback<T, U extends CustomException> {

    void onSuccess(T response);

    void onFailure(U error);
}

genericsproject_exceptions_BarException.java

package com.lbalmaceda.genericsproject.exceptions;

/**
 * Created by lbalmaceda on 6/21/16.
 */
public class BarException extends CustomException{
    public BarException(String message) {
        super(message);
    }
}

genericsproject_exceptions_CustomException.java

package com.lbalmaceda.genericsproject.exceptions;

/**
 * Created by lbalmaceda on 6/21/16.
 */
public class CustomException extends Exception {
    public CustomException(String message) {
        super(message);
    }
}

genericsproject_exceptions_FooException.java

package com.lbalmaceda.genericsproject.exceptions;

/**
 * Created by lbalmaceda on 6/21/16.
 */
public class FooException extends CustomException{
    public FooException(String message) {
        super(message);
    }
}

genericsproject_MainActivity.java

package com.lbalmaceda.genericsproject;

import android.os.Bundle;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;

import com.lbalmaceda.genericsproject.exceptions.BarException;
import com.lbalmaceda.genericsproject.exceptions.FooException;
import com.lbalmaceda.genericsproject.requests.BarRequest;
import com.lbalmaceda.genericsproject.requests.FooRequest;

public class MainActivity extends AppCompatActivity {
    private static String TAG = MainActivity.class.getSimpleName();
    private Handler handler;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        handler = new Handler(MainActivity.this.getMainLooper());

        FooRequest<String> simpleRequest = new FooRequest<>(simpleCallback);
        simpleRequest.start();
        BarRequest voidRequest = new BarRequest(voidCallback);
        voidRequest.start();
    }

    private void showToast(final String message) {
        handler.post(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(MainActivity.this, message, Toast.LENGTH_SHORT).show();
            }
        });
    }

    private CustomCallback<String, FooException> simpleCallback = new CustomCallback<String, FooException>() {
        @Override
        public void onSuccess(String response) {
            Log.e(TAG, "OnSuccess for SimpleCallback");
            showToast("SimpleRequest fine!");
        }

        @Override
        public void onFailure(FooException error) {
            Log.e(TAG, "OnFailure for SimpleCallback");
        }
    };

    private CustomCallback<Void, BarException> voidCallback = new CustomCallback<Void, BarException>() {
        @Override
        public void onSuccess(Void response) {
            Log.e(TAG, "OnSuccess for VoidCallback");
            showToast("VoidRequest fine!");
        }

        @Override
        public void onFailure(BarException error) {
            Log.e(TAG, "OnFailure for VoidCallback");
        }
    };
}

genericsproject_requests_BarRequest.java

package com.lbalmaceda.genericsproject.requests;

import com.lbalmaceda.genericsproject.CustomCallback;
import com.lbalmaceda.genericsproject.exceptions.BarException;

/**
 * Created by lbalmaceda on 6/21/16.
 */
public class BarRequest extends BaseRequest<Void, BarException> {

    public BarRequest(CustomCallback<Void, BarException> callback) {
        super(callback);
    }

    @Override
    protected Void generateSuccess() {
        return null;
    }

    @Override
    protected BarException generateException() {
        return new BarException("BarBar");
    }
}

genericsproject_requests_BaseRequest.java

package com.lbalmaceda.genericsproject.requests;

import android.os.Handler;
import android.util.Log;

import com.lbalmaceda.genericsproject.CustomCallback;
import com.lbalmaceda.genericsproject.exceptions.CustomException;

/**
 * Created by lbalmaceda on 6/21/16.
 */
abstract class BaseRequest<T, U extends CustomException> {

    private static final String TAG = BaseRequest.class.getSimpleName();
    private final CustomCallback<T, U> callback;

    public BaseRequest(CustomCallback<T, U> callback) {
        this.callback = callback;
    }

    public void start() {
        Handler handler = new Handler();
        handler.post(runnable);
    }

    private Runnable runnable = new Runnable() {
        @Override
        public void run() {
            Log.e(TAG, "Thread starting");
            try {
                Thread.sleep(3000);
                callback.onSuccess(generateSuccess());
                Log.e(TAG, "Thread ended fine");
            } catch (InterruptedException ignored) {
                Log.e(TAG, "Thread ended with error");
                callback.onFailure(generateException());
            }
        }
    };

    protected abstract T generateSuccess();

    protected abstract U generateException();
}

genericsproject_requests_FooRequest.java

package com.lbalmaceda.genericsproject.requests;

import com.lbalmaceda.genericsproject.CustomCallback;
import com.lbalmaceda.genericsproject.exceptions.FooException;

/**
 * Created by lbalmaceda on 6/21/16.
 */
public class FooRequest<T> extends BaseRequest<T, FooException>{

    public FooRequest(CustomCallback<T, FooException> callback) {
        super(callback);
    }

    @Override
    protected T generateSuccess() {
        return null;
    }

    @Override
    protected FooException generateException() {
        return new FooException("BarBar");
    }

}