操作符入门：
RxJava 操作符的类型分为创建操作符、变换操作符、过滤操作符、组合操作符、错误处理操作符、辅助操作符、条件和布尔操作符、算数和聚合操作符及连接操作符等。而这些操作符类型下又有很多操作，每个操作又有很多变体。
常用的创建操作符：
常用的有 create、just、from
不常用的有 defer、range、interval、start、repeat 和 timer
一、just操作符方法
创建发送指定值的Observerble，just只是简单的原样发射，将数组或Iterable当做单个数据。如果传递的值为null，则发送的Observable的值为null。参数最多为9个。
Observable<String> myObservable = Observable.just("just1","just1","just1","just1","just1","just1","just1","just1","just1","just1");
Subscriber<String> mySubscriber = new Subscriber<String>() {
@Override
public void onNext(String s) {
System.out.println(s);
}
@Override
public void onCompleted() {
System.out.println("onCompleted.................");
}
@Override
public void onError(Throwable e) {
System.out.println("onError....................");
}
};
myObservable.subscribe(mySubscriber);
二、from方法
将数据转换成为Observables，而不是需要混合使用Observables和其它类型的数据。
String[]items = {"just1","just1","just1","just1","just1","just1"};
Observable<String> myObservable = Observable.from(items);
Subscriber<String> mySubscriber = new Subscriber<String>() {
@Override
public void onNext(String s) {
System.out.println(s);
}
@Override
public void onCompleted() {
System.out.println("onCompleted.................");
}
@Override
public void onError(Throwable e) {
System.out.println("onError....................");
}
};
myObservable.subscribe(mySubscriber);
三、repeat方法
1.repeat()重复地执行某个操作，如果不传递参数，结果将会被无限地重复执行，默认在trampoline调度器上执行，该方法为非静态方法，不可以直接通过Observable来调用
String[]items = {"just1","just2","just3","just4","just5","just6"};
Observable<String> myObservable = Observable.from(items).repeat();
Subscriber<String> mySubscriber = new Subscriber<String>() {
@Override
public void onNext(String s) {
System.out.println(s);
}
@Override
public void onCompleted() {
System.out.println("onCompleted.................");
}
@Override
public void onError(Throwable e) {
System.out.println("onError....................");
}
};
myObservable.subscribe(mySubscriber);
2.repeat()如果传入数字类型的参数，则重复地执行指定次数的某个操作，默认在trampoline调度器上执行，不可以直接通过Observable来调用
String[]items = {"just1","just2","just3","just4","just5","just6"};
Observable<String> myObservable = Observable.from(items).repeat(2);
Subscriber<String> mySubscriber = new Subscriber<String>() {
@Override
public void onNext(String s) {
System.out.println(s);
}
@Override
public void onCompleted() {
System.out.println("onCompleted.................");
}
@Override
public void onError(Throwable e) {
System.out.println("onError....................");
}
};
myObservable.subscribe(mySubscriber);
3.repeatWhen()不是缓存和重放原始Observable的数据序列，而是有条件的重新订阅和发射原来的Observable,当Observable中的call()方法中调用了重复执行的代码时，onNext()将会被重复执行。如果该方法执行后返回void，则结束执行
final String[]items = {"just1","just2","just3","just4","just5","just6"};
Observable<String> myObservable = Observable.from(items).repeatWhen(new Func1<Observable<? extends Void>, Observable<?>>() {
@Override
public Observable<?> call(Observable<? extends Void> observable) {
return observable.delay(5, TimeUnit.SECONDS);
}
});
Subscriber<String> mySubscriber = new Subscriber<String>() {
@Override
public void onNext(String s) {
System.out.println("onNext.................."+s);
}
@Override
public void onCompleted() {
System.out.println("onCompleted.................");
}
@Override
public void onError(Throwable e) {
System.out.println("onError....................");
}
};
myObservable.subscribe(mySubscriber);
