In RxJava, groupBy divides an Observable into several Observable sets. Each of them transmits a subsequence of the original Observable. Which data item is transmitted by which Observable is determined by a function. This function specifies a Key for each item, and the data with the same Key will be transmitted by the same Observable.
Let's look at an example to see:
ArrayList<Object> list = new ArrayList<Object>();
list.add(new Person());
list.add(new Person());
list.add(new Student());
list.add(new Student());
list.add(new Person());
list.add(new Student());
list.add(new Student());
Observable.from(list)
.groupBy(new Func1<Object, Integer>() {
@Override
public Integer call(Object o) {
if (o.getClass().getName().equals(Person.class.getName())) {
return 1;
} else {
return 2;
}
}
})
.subscribe(integerObjectGroupedObservable -> {
int key = integerObjectGroupedObservable.getKey();
switch (key) {
case 1:
integerObjectGroupedObservable.subscribe(new Action1<Object>() {
@Override
public void call(Object o) {
Log.e("groupBy", "call: Receive Person object");
}
});
break;
case 2:
integerObjectGroupedObservable.subscribe(new Action1<Object>() {
@Override
public void call(Object o) {
Log.e("groupBy", "call: Receive Student object");
}
});
break;
}
});
Result:
call: receive Person object call: receive Person object call: receive Student object call: receive Student object call: receive Person object call: receive Student object call: receive Student object
In the Func1() function of GroupBy, group by your logic and return the key flag of the group corresponding to each information. For example, each flag of my group is of Integer type. GroupBy will return a special subclass of Observable, GroupedObservable, which has an extra method getKey(), which can be used to obtain the current information group.
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