前言
根据Froussios英文版的学习笔记。
一、count
计算原始Observable发射物的数量，然后只发射这个值
例如 发射1 2 3 ，count()结果为3
二、first(T defaultItem) 与 firstElement()
- first :如果没有第一个值，则返回defaultItem
- firstElement: 如果没有第一个值，则complete 流。
三、last(T defaultItem) 与 lastElement()
同first，只是发射的是最后一个值
四、single(T defaultItem) 与 singleElement()
- singleElement(): Observable至发射一个数据，否则报错
- single(T defaultItem) ： 没有发射任何数据，则返回defaultItem
五、reduce、scan与collect
-
reduce :按顺序对Observable发射的每项数据应用一个函数并发射最终的值
reduce
Observable.just(1,2,4)
.reduce(new BiFunction<Integer, Integer, Integer>() {
@Override
public Integer apply(Integer integer, Integer integer2) throws Exception {
Log.d("pngpng",integer+"--"+integer2);
return integer+integer2;
}
})
.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
Log.d("pngpng", o + "");
}
}, throwable -> Log.e("pngpng", "just error", throwable));
结果如下：
D/pngpng: 1--2
D/pngpng: 3--4
D/pngpng: 7
Observable.just(1,2,4)
.reduce(10,new BiFunction<Integer, Integer, Integer>() {
@Override
public Integer apply(Integer integer, Integer integer2) throws Exception {
Log.d("pngpng",integer+"--"+integer2);
return integer+integer2;
}
})
.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
Log.d("pngpng", o + "");
}
}, throwable -> Log.e("pngpng", "just error", throwable));
结果如下：
D/pngpng: 10--1
D/pngpng: 11--2
D/pngpng: 13--4
D/pngpng: 17
-
scan: 连续地对数据序列的每一项应用一个函数，然后连续发射结果
scan collect:收集所有的数据到一个可变的数据结构
Observable.just(1, 2, 4)
.collect((Callable<List<Integer>>) ArrayList::new,
(o, integer) -> {
o.add(integer);
})
.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
Log.d("pngpng", o + "");
}
}, throwable -> Log.e("pngpng", "just error", throwable));
结果为：
D/pngpng: [1, 2, 4]
六、toList与toSortedList
- toList :按照顺序获得一个list
- toSortedList:按照自定义顺序获取list
Observable.just(1, 2, 4)
.toSortedList(new Comparator<Integer>() {
@Override
public int compare(Integer integer, Integer t1) {
return t1-integer;
}
})
.subscribe(new Consumer<Object>() {
@Override
public void accept(Object o) throws Exception {
Log.d("pngpng", o + "");
}
}, throwable -> Log.e("pngpng", "just error", throwable));
结果为：
D/pngpng: [4, 2, 1]
七、toMap 与toMultimap
- toMap ：转化成map
public final <K> Observable<java.util.Map<K,T>> toMap(
Func1<? super T,? extends K> keySelector)
public final <K,V> Observable<java.util.Map<K,V>> toMap(
Func1<? super T,? extends K> keySelector,
Func1<? super T,? extends V> valueSelector)
public final <K,V> Observable<java.util.Map<K,V>> toMap(
Func1<? super T,? extends K> keySelector,
Func1<? super T,? extends V> valueSelector,
Func0<? extends java.util.Map<K,V>> mapFactory)
举个例子：
Observable.just(1, 2, 2, 3)
.toMap(new Function<Integer, Integer>() {
@Override
public Integer apply(Integer integer) throws Exception {
return integer;
}
}, new Function<Integer, String>() {
@Override
public String apply(Integer integer) throws Exception {
return integer + "自定义";
}
})
.subscribe(new Consumer<Map<Integer, String>>() {
@Override
public void accept(Map<Integer, String> o) throws Exception {
Log.d("pngpng", o + "");
}
}, throwable -> Log.e("pngpng", "just error", throwable));
结果为：
D/pngpng: {1=1自定义, 3=3自定义, 2=2自定义}
- toMutitleMap
Observable.just(1, 2, 2,3)
.toMultimap(new Function<Integer, Integer>() {
@Override
public Integer apply(Integer integer) throws Exception {
return integer ;
}
}, new Function<Integer, String>() {
@Override
public String apply(Integer integer) throws Exception {
return integer+"自定义";
}
})
.subscribe(new Consumer<Map<Integer,Collection<String>>>() {
@Override
public void accept(Map<Integer,Collection<String>> o) throws Exception {
Log.d("pngpng", o + "");
}
}, throwable -> Log.e("pngpng", "just error", throwable));
结果为
D/pngpng: {1=[1自定义], 3=[3自定义], 2=[2自定义, 2自定义]}
后记
一定要收藏好https://rxmarbles.com/ 这个网址，记不得的时候去看看就好啦，图片很详细的。
