ReduceExampleActivity.java

package com.rxjava2.android.samples.ui.operators;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.rxjava2.android.samples.R;
import com.rxjava2.android.samples.utils.AppConstant;

import androidx.appcompat.app.AppCompatActivity;
import io.reactivex.MaybeObserver;
import io.reactivex.Observable;
import io.reactivex.disposables.Disposable;
import io.reactivex.functions.BiFunction;

/**
 * Created by amitshekhar on 27/08/16.
 */
public class ReduceExampleActivity extends AppCompatActivity {

    private static final String TAG = ReduceExampleActivity.class.getSimpleName();
    Button btn;
    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_example);
        btn = findViewById(R.id.btn);
        textView = findViewById(R.id.textView);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                doSomeWork();
            }
        });
    }

    /*
     * simple example using reduce to add all the number
     */
    private void doSomeWork() {
        getObservable()
                .reduce(new BiFunction<Integer, Integer, Integer>() {
                    @Override
                    public Integer apply(Integer t1, Integer t2) {
                        return t1 + t2;
                    }
                })
                .subscribe(getObserver());
    }

    private Observable<Integer> getObservable() {
        return Observable.just(1, 2, 3, 4);
    }

    private MaybeObserver<Integer> getObserver() {
        return new MaybeObserver<Integer>() {
            @Override
            public void onSubscribe(Disposable d) {
                Log.d(TAG, " onSubscribe : " + d.isDisposed());
            }

            @Override
            public void onSuccess(Integer value) {
                textView.append(" onSuccess : value : " + value);
                textView.append(AppConstant.LINE_SEPARATOR);
                Log.d(TAG, " onSuccess : value : " + value);
            }

            @Override
            public void onError(Throwable e) {
                textView.append(" onError : " + e.getMessage());
                textView.append(AppConstant.LINE_SEPARATOR);
                Log.d(TAG, " onError : " + e.getMessage());
            }

            @Override
            public void onComplete() {
                textView.append(" onComplete");
                textView.append(AppConstant.LINE_SEPARATOR);
                Log.d(TAG, " onComplete");
            }
        };
    }


}