RxJava2 / RxAndroid2的过滤器filter

RxJava2 / RxAndroid2的过滤器filter

filter完成一个条件过滤和筛选，从Observable的输出数据中，经过filter筛选一层，如果filter判断的值为真，则交给观察者，否则跳过，例如代码：

package zhangphil.app;

import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;

import io.reactivex.Observable;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.disposables.CompositeDisposable;
import io.reactivex.functions.Predicate;
import io.reactivex.observers.DisposableObserver;
import io.reactivex.schedulers.Schedulers;

public class MainActivity extends AppCompatActivity {
    private final String TAG = getClass().getSimpleName();
    private CompositeDisposable mCompositeDisposable = new CompositeDisposable();

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        test();
    }

    private void test() {
        DisposableObserver disposableObserver = new DisposableObserver<Integer>() {
            @Override
            public void onNext(Integer i) {
                Log.d(TAG, "#####开始#####");
                Log.d(TAG + "数据", String.valueOf(i));
                Log.d(TAG, "#####结束#####");
            }

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

            @Override
            public void onError(Throwable e) {
                Log.e(TAG, e.toString(), e);
            }
        };

        mCompositeDisposable.add(
                getObservable().filter(new Predicate<Integer>() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        int result = integer % 10;
                        boolean b = (result == 0);
                        return b; // 此处返回的条件若为true，则数据交给观察者 ,否则跳过
                    }
                })
                        .subscribeOn(Schedulers.io())
                        .observeOn(AndroidSchedulers.mainThread())
                        .subscribeWith(disposableObserver));
    }

    private Observable<Integer> getObservable() {
        return Observable.range(0, 100);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        // 如果退出程序，就清除后台任务
        mCompositeDisposable.clear();
    }
}

代码输出：

05-15 17:15:49.664 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.664 29872-29872/zhangphil.app D/MainActivity数据: 0
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 10
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 20
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 30
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 40
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 50
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 60
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 70
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 80
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####开始#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity数据: 90
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: #####结束#####
05-15 17:15:49.665 29872-29872/zhangphil.app D/MainActivity: onComplete