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