本文主要是介绍RxJava2 / RxAndroid2的过滤器filter，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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();@Overridepublic void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);test();}private void test() {DisposableObserver disposableObserver = new DisposableObserver<Integer>() {@Overridepublic void onNext(Integer i) {Log.d(TAG, "#####开始#####");Log.d(TAG + "数据", String.valueOf(i));Log.d(TAG, "#####结束#####");}@Overridepublic void onComplete() {Log.d(TAG, "onComplete");}@Overridepublic void onError(Throwable e) {Log.e(TAG, e.toString(), e);}};mCompositeDisposable.add(getObservable().filter(new Predicate<Integer>() {@Overridepublic 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);}@Overrideprotected 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
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